Certainly wasn’t expecting a mention… and I was still laughing at Edwin’s antics when it came up! Anyway, re: the KB incident, if your previous videos didn’t convince people that your design will not fail under (anything approaching) normal use, I’m not sure anything will. It sucks that you need to defend your good name.
and KB did a video it as well and its seems a lot of people in the comments haven't seen it and KB did it with a barrett the gold standard of 50 cals and it blew up just the same.
One of the most telling things about this whole debacle is that I've only heard criticism of the design come from non-engineers. As an aerospace engineer, we don't design for margins anywhere near what you do, so when I hear that the action failed at 400% of the cartridge spec it's amazing to me that it got that far. Nobody expects you to be able to take a Honda civic and flow 10 kg/s of nitrous through the engine without catastrophic failure. Guns for so many people in the community are just strange magical blackboxes bullets come out of and God forbid if you remind them they are machines like any other.
Not an engineer, but when reviewing pressure tanks that exploded, the one part always intact was the threads. Just seemed like common sense that threads were always a stronger connection in pressure situations than lugs. Wish the so-called UA-cam-experts would have discussed that and shut down some of the hyperventilating about a threaded breech.
I fuind it amazing how the stoner ar design was great BECAUSE, a aerospace engineer designed it... imagine how great an airplane would have been if designed by a gunsmith?
If all guns were designed for the absolute max compressed load of the fastest burning powder available for the particular round chambered, you can bet the farm that the same complainers would be boohooing about how heavy and massively overdesigned the weapon is. Why does my 300 winmag have to weigh 20lbs stripped?
On the flip side, thinking about consciously putting your face mere inches from an explosion with tens of thousands of PSI's of pressure to simply expel a small bit of metal in an intended direction isn't something that everyone really wants to think about.
A man almost died. Regardless of any factor, every single thing related to that accident requires in depth analysis. A lot of companies, once they realized they were clear of a lawsuit, wouldn't have given two fucks. The fact that Mark himself cares enough to dedicate this much time to the incident after the fact really says a lot of positive things about the company.
This is where I was going to go with my comment. Mark is going way beyond the call of duty with his continuing analysis. I would suspect he donated the testing guns to KB for his destructive tests. Edwin mentioned he was sending his back to Mark after his concrete testing, I’d bet Mark ate that one as well. If I had a desire for one I would not hesitate to buy and use. I’ve shot 50’s and I don’t see any practicality in it for me.
@Kinzie Conrad Did you not even watch the video? They buried the barrel in 4 feet of concrete and it still didn't break the threads, you're an idiot lol
The problem with surplus of unknown storage and transportation history, some could get exposed to excessive heat and/or movement, degrading the inhibitors, greatly increasing burn rate.
I find it “funny” that even though Scott himself said the gun was not to blame people went out of their way to make assumptions and call you/your business out based on nothing but speculation.
@@manbaby9166 New Kentucky Ballistics Mascot be like Scott-borg, a man of steel and heart who has come from the future to stop evil inflatable dinosaurs and eggplants
I think part of it is the design already sketched a lot of people out. Tbh before all this I saw the rn50 and was like fuck no, that things like a fucking factory made pipe gun, I don't trust that not to become a factory made pipe bomb in my hands. When KB happened i was like "it was only a matter of time". Ironically in the long run it took it blowing up to convince me I should get one. After having seen all the testing I'm a lot more confident in it being safe and fun to own.
I'm a bit flabbergasted how people thought a piece of plastic had enough tensile strength to withstand enough force for the back of the gun to blow up rather than the plastic. ON WHAT PLANET IS THAT POSSIBLE? - ok watching the rest of the video now.
@@markserbu Even worse: Shotguns with chokes. D: Honestly, people making these comments likely didn't watch any video on the matter to the end, and have invested exactly 0 seconds into thinking about / reading into materials science.
Exactly what I thought from the very beginning! It had to be something other than the proper powder loaded in that round. Glad Mark is vocal about this and calling out the stupid “dog bark”ing people and their comments.
Most people are dumb...They don't try to understand the physics behind something and they make up what reasons they think work best instead of actually listening to engineers and other S.T.E.M. qualified people that can explain it through math and sketches. As for the younger generation ..we've seen so much dumb shit online we can spot a troll most of the times.
From the test that Kentucky Ballistics did, someone tampered with the SLAP rounds that he bought, and loaded them way too hot. The ammo was to blame, not the rifle.
When you obtain ammo that has never been offered to the public, what is available "fell off a truck somewhere", you are taking a very big risk especially considering the price these rounds bring.
@@aethelon4144 No, it had to be the wrong powder. Even a compacted load in the .50 wouldn't cause that serious of an over pressure, it was most likely pistol powder.
@@ZE0XE0 The burning rate of the powder used is very important, faster powder as used in pistols is less dense than slower powders used in rifles, a case full of fast pistol powder could be responsible. Or something other than gun powder inside the case.
Kentucky’s blowup, from the perspective of a reloader, looks like classic overloaded round. Barrel obstructions USUALLY banana peel the barrel, not blow the back of the bolt/chamber open. Especially seeing him fire the rest of the ammo from that batch he bought, almost every last one gave clear and loud warnings of a hot load. Whether the failure mode of the RN-50 could or should be different is another conversation, but the ammo caused the blowup. I’d bet a not inconsequential amount of money on it.
A little stupid thing that some ill educated gun nuts do is clean and shine their loaded brass in a vibrator , a big no no, you literally remove all coatings off the powder and if it's double base powder you quite literally have made a very destructive instrument, can't say the word UA-cam won't let me , video creators can but commenters cannot.
As seen by his other demo tests of guns, there's not really a design out there that would be much safer than the RN. The Barrett is the gold standard .50 and that thing would've still likely killed him
I could see that as well. In all of the pictures I've seen of obstructed barrels being fired into, there was ALWAYS at least a bulge starting near the obstruction point, and very often splitting. It's the thing every reloading manual has warnings about. An over-charge can cause excessive wear or binding on the action and a massive over-charge will blow out the action. The pressure spikes too high before the bullet gets out of the barrel. The fact that all but one of those SLAP rounds were over-charged to an extent is plenty of evidence that one or two could be explosively so. When you're hammering, or otherwise using tools and force, to open the action, your rounds are too hot. Except on a Mosin. Hammering is expected.
@@Robert-qm7yi This was my thought as well. That pressure wants to go somewhere, and if it's going anywhere but forward, there's a good chance you're going to be on the receiving end of whatever that pressure is dumping it's kinetic buildup into. Be it the end cap and lugs of the gun, or the remains of the receiver folding over backwards into your face. At the end of the day, you're sitting inches away from a contained explosion that's almost _four times_ the rated pressure of the rifle, at an already extreme pressure rating. The only way i see to account for that is to over-engineer the hell out of it and hope it doesn't fail, because at those kinds of pressures, no failure mode is going to be pretty. EDIT: Forgot how fucking insane the pressure actually was, just looked it back up because i wasn't sure. I still can't believe Scott's alive.
What is failsafe? You cannot prevent failure, but you can make it fail more safely. For example, if the top of the barrel was intentionally made weaker than the cap, then the rifle would blow-up upwards, instead of blowing-up in your face.
The only thing that scares me about my RN50 is the thought of carrying it more than 20 feet. And firing more than 10 rounds in one sitting. Fantastic rifle and the most cost efficient method of delivering 50bmg to a target.
@@jacobkudrowich The only difference between men and boys is the price of their toys. If putting 30 bucks of ammo up in smoke bothers you don’t ever own/shoot a machine gun, Gatling gun or shoot rifles chambered in most classic “dangerous game” cartridges. This is why traditionally most metallic and competitive shotgun shooters reload their own ammunition. For me and many other shooters who reload their ammunition it brings another element of enjoyment to shooting sports.
Anyone who's taken a physics course, or a materials course... and passed, knows that the pressure required to rip the threads off even a grade 5 bolt of that size is phenomenal. Mark builds a good gun. I just got my new Serbu 50 cal and shot it the first time last weekend... not a worry in my mind. Keep up the good work, Mark.
Obviously everyone who's talking shit about the gun doesn't know anything about engineering and design. A part (can be just a beam of steel, but here the gun) has to withstand certain forces. It shall be designed in a way it's safe for normal use. For mistakes and stuff the part can usually withstand around 1.5 times the normal force. Beyond that, it's not the designer's fault.
You forgot to multiply the thread load capacity by the 2 fucking 1/4" steel backers behind it that the cap completely sheared off like they didn't exist. People are just ignorant. I don't know where the 200k psi rating Mark threw out came from but it seems a little low to me. To move a cap backwards fast enough AFTER failure to sheer off that much steel, it had to be SIGNIFICANTLY over the failure load, not just slightly. If it was slightly over it would have dented the steel and then deflected up.
US Army small arms repairer here. IIRC, it has been many years, sabot rounds arent supposed to be used with a muzzle brake OR flash hider. (yes even the conical flash hider for the M2) because the sabot separates from the round at the end of the rifling. If a muzzle device is attached it can cause the discarded sabot to ricochet off the device and strike the round, causing a deviation in the point of impact. It doesnt happen often, but often enough for the US military to advise against it. A micro deviation at or near the muzzle, can have a huge impact at 1200 meters and beyond. Small dents and dings in a flash hider have very little impact on the weapons operation. A round striking 50- 100 meters outside the impact zone, can have catastrophic results for both the Military, and any civilians or military personnel outside the impact zone. 5 of the 6 branches I know use both the M2 and the Barrett, USA, USMC, USN, USAF, and USCG. I have no information on if the USSF uses either system. The directive on this did not come from any of the branches individually, rather it was a DoD issued directive. Just my humble opinion based on the information I have been exposed to over 28 years in the US Army. I could be wrong.
m.ua-cam.com/video/3c4wtfV5_ao/v-deo.html In this video he says it's not the slap engaging with the muzzle. He also hates my idea of chamber vents. I don't see whats wrong with the chamber vent idea.
I know they didn't let our sneaky squirrels use them in the barrets. They didn't like us using them in the ma duce that much either. I could be wrong, but it's my opinion that was mostly because those rounds were getting pretty old and they didn't trust them much because of the age. I'm pretty sure we only had once can issued in our entire company, and we got it on a fluke. After the accident I tend to agree. I'm pretty sure that nobody has loaded new SLAP rounds in a very long time.
Hey Mark 🙋it was clear after Scott's test video, that the ammo was significantly overcharged. If gas prices weren't so godawful high I'd put an order in for an RN50 today. Keep being awesome.
For some reason they decide to go on a witch hunt after Mark even though the ammo used during the accident was, as you said, overcharged. A normal .50 round would never be able to shear the steel threads on the rn50. (In my opinion)
Interesting fact I learned afterwards is that a "undercharged" round can also blow up stuff badly. At first it don't make sense. Once you think about it tho if a round has more powder inside it, less surface area of the grains of powder are exposed to the flash over as it ignites. However if you have less powder it exposes up to like 3× more powder right away as it flashes over and it will cause a higher initial spike of pressure. A casing loaded with more powder has a longer explosion but at a slower rate. If that makes any sense lol. Then a cartridge that has a round pushed down inside it will go off like a stick of dynamite as it will go off nearly at once and have the highest spike I think. Someone who knows this stuff better can weigh in and explain it all better. Neat stuff tho. Unless you're the guy being exploded. Then it kinda cramps your style a bit lol Just go ahead and give yourself a tracheodomy before testing weird loads made by a stranger and you'll be fine lol
@@hughgrection3052 this is common in nitromethene racing, they literally wash the cylinders with fuel, so much so that the engine is constantly teetering on Hydro lock, even at red line. If you want to hear more, let me know
Thanks' so much Mark, this was great info I didn't know. We shoot a lot of SLAP rounds on our channel but were only going off what everyone else said as far as muzzle brakes go when we first started shooting the SLAP rounds. At first, we were shooting them with the brake off, but the dang thing kicked so much Justin made an insert (basically a machined tube with a bunch of holes in it) for our Bushmaster BA50's big old honking brake and it works just fine. Thanks for the common since showing the footage of the rifle blowing up, and one no in cement. It doesn't much clearer than that.
@Going Ballistic Thanks! As pretty much everyone knows, the plastic sabot *can* damage a muzzle brake. In extreme cases, pieces can be blown off and fly backwards at bullet speed. Hell, in the prototype phase of the BFG-50A we had brakes lose some pretty big chunks, and that was just from propellant gas! Excellent idea with the perforated tube insert!
Same here @David Hughes! I can see how uncomfortable saying some of this is making Mark Serbu!, and learning internet culture where Keyboard Warriors can verbally assault people who they wouldn't fecking *DARE* to mouth off face to face is a lesson that can be hard to learn!. Fair play to Mark for his openness!... As for Failsafe, I.E. PROOF-ing *anything!* a great *Old* saying is it's hard to *FOOL* -proof *ANYTHING* because they just keep making more ingenious *FOOLS!* by the way that's not a dig at *KB* ,I think Scott is cool as feck! Keep your head up and keep doing your thing Mark!
I want to see a knock off version of RN-50 by Hi-Point or some other low-end manufacturer from China or Ghana or Peshawar....then we can look forward to some real carnage.
All BS aside, the RN50s rep took a beating in the court of public opinion. I could not imagine anything more infuriating than being judged on something,that the firearm was never designed for,by a bunch of people that know just enough to sound like they know what they are talking about. Carry on Mark. Thank you for doing all you can to educate the masses.
@@CAMSLAYER13 The ammo was in question from very early on, it was determined it was the slap rounds mere weeks after incident happened, it was covered by marked himself then not long after that KB destroyed another RN 50 to demonstrate the forces needed to destroy the breach cap as well as the lugs that everyone likes to get philosophical about. Truth is nothing would have survived that,… there was a dude not long ago that loaded a tube mag shotty with questionable ammo… it chain fired the whole mag disintegrating the fire arm and indeed his own arm. Now , do we demonize that model of shot gun because of the incorrect ammo, or,as animals equipped with the powers of deduction, rather than flock mentality, do we identify and remove the greater hazards? Mark is clearly annoyed and rightly so. Half informed critics are as useless as biased ones.
@@riz3nfpv306 He has every right to be upset but, unfortunately it's the way it is, the damage done cannot be reversed. Sucks for him, but the gun has a bad reputation now. KB's video will always have more views than any of these video's, only very few people in contrast will see any of the breakdown videos.
@@kinzieconrad105are you saying it blew up because of the threaded breach cap? Do you think an m4a1 would have done better ? Get educated bud… or be one of the guys we can laugh at
@@Chzydawg I don’t know which are dumb and which are dumber. The ones starting the BS or the ones Taking it as the truth. It actually is saddening, you need to remember producing an item to supply to the public is a difficult enough task. You guys are blessed to have guys like mark in your country to design and supply these products. Also the birth of the RN50 was to supply a need in the market for a budget 50 cal…he listened to that need,why tear him down? If a guy like mark comes under scrutiny from his peers in his community, and is found free of liability, he should be supported. Not continually dragged through the mud Ok fair ,in the name of safety - IF the gun was faulty sure get it out there - but it’s not , why keep up this fallacy or misinformation? Why not go after the guys that supplied the rounds?I don’t get it.
Been following along from the beginning. As a Mechanical Engineer (now retired) specializing in Forensic Failure Analysis for over half of my career, I find it fascinating the process you have gone through to this point! There's an old saying: "The Devil is in the details". 🤔
Regarding "fail safe". This is like when people ask locksmiths for locks/chain that will stand up to an angle grinder cutoff wheel. **Nothing** stands up to a cutoff wheel. "Okay so we sell this hardened security chain by the foot, right?" "Yeah..." "How do you think we cut it to length?" "... oh."
@@mephInc Surely the criminals won't take the path of least resistance... surely... Of course, depending on how high said criminal is, ya never really know!
Before the gun blew up, I always thought the design of the RN-50 breech screw plug was just supposed to be a cheap way to make a gun. Never considered the safety. Then I researched the sheer strength of threads vs lugs. It’s amazing how much more secure threads are than lugs. So, the RN-50 is probably more safe than the other 50 cal rifles.
Threads are only safer when properly machined and torqued. Threads also don't take very well to wear and repeated cycles as well as lugs do, which is why they're the most common design.
Threads were used on breech loading cannons right up until WW1 and are still used in some modern artillery. Talishar doesn't seem to be the most informed commenter on this. He has a point about thread wear but as I said interrupted threads are used in some modern artillery to this day. The RN-50's design has the ears to ensure the minimum amount of thread length engagement. I don't believe the RN-50 uses a tapered thread so... meh If he really thinks the design is unsafe, I'd love for him to put his money where his mouth is and do the Reliability Analysis. Show me the weibull baby!!
You are 100% correct. I’m a retired engineer and I know that what happens at the muzzle brake can not cause the chamber to fail. The muzzle brake is the weakest part of the weapon, and by the time a projectile reaches the brake the chamber has already reached and passed its maximum pressure.
Also the fact that there was no damage to the barrel, no expansion or peeling, proved that as being wrong. The barrel is strong, but it would be an extreme oddity for a barrel of any kind to be stronger than the chamber. The nature of gun design alone makes that unlikely, and the fact that the barrel is threaded into the receiver which is providing additional support for the chamber. It was clear to me from the first video of the explosion that it was a massive over-charge, and when things exceed the expected worst-case possibility design, it is impossible to predict the outcome.
Common sense is a flower that does not grow in everyone's garden. It's refreshing how confident you are in your engineering and your willingness to tell people they are idiots when they are being idiots. Entirely too many people are overthinking this entire incident and looking to place blame where it doesn't belong. Keep up the great work.
I'm glad that Mark (although jokingly) called out Edwin about his Oxygen Bottle in a Safe antics........ that was super stupid. Sarkissian should know better than that.
I had been looking at buying an RN-50 from my LGS for a while. I bought mine AFTER Scott's blew up. Why? Because of YOUR immediate and calm response AND because of what I saw in the damaged breech end. The fracturing pattern in the threads showed clear excessive pressure. You build great guns. I love my RN-50. Thanks again for refuting the garbage others have put out about Scott's accident.
It was very clear from his response to the accident that he's the sort of guy you can trust. He was very concerned with finding out the cause and address it if there was a design flaw or manufacturing issue. The problem didn't turn out to be on his end, but it was obvious he was focused on finding out.
I would prefer a bolt-action or automatic .50, but seeing those threads hold themselves from a dozen mystery cartridges embossing their headstamp into the breech plug, that makes me confident enough to a box of proof loads with the thing without breaking a sweat.
The way Mark has handled this-- and this video in particular-- really inspires confidence. I'm an engineer and gun enthusiast and all of Mark's remarks have my engineer brain nodding in violent approval. There's no such thing as fail-proof. Just fail-resistant. For example, I can layout some hydraulic hoses with different sized ends to make it only go together one way, but a trip to the local hose shop for an adapter and just like that it's plumbed wrong. Mark's analysis is spot on, and it shows a dogged determination to vindicate his design-- which I sure as heck would also want to do if it was MY rifle that ignorant people were accusing of being at fault.
Weak threads? Anyone ever look at hydraulic cylinders? Its all held together by fine threads that hold back all that pressure for hundreds of thousands of cycles. 100% wasn't the fault of the threads, definitely an over charged round or and war relic sabotage round with C4 in it that happened to find its way into that batch of ammo. I'd definitely recommend weighing each round of ammo looking for discrepancies when buying old ammo or from anyone really when talking about .50BMG.
Some artillery pieces use an interrupted thread to secure the breach plug. There is absolutely nothing wrong with a threaded plug or cap with adequate sized threads and proper contact. Given that Scott from KY Ballistics did another test and ran seriously overpressure rounds through an RN50 without failure, I'd say the RN50 is just fine. It took making what was effectively a little pipe bomb to break the gun.
@@RustandRedemption The engine in your car does the same thing with a spark plug. An engine at 3000RPM is spinning 50 times a second and in a 4-cycle engine, that means 25 explosions per second per cylinder that your spark plug not only contains, but ignites as well, thus placing itself at ground zero for the combustion event. Absolutely nothing wrong with threaded plugs or caps.
the people pointing out the "weaknesses" of the screw cap clearly have never seen how artillery or naval guns work... those breach blocks are literally threaded, well partially since they're typically a 90° lock which means there's LESS material thread wise in contact between the block and the barrel.
Yeah in the military we had way worse examples that didnt fail. Now I have never fired a RN50 but I would trust its screw cap, because I trusted things like chicago fittings for high pressure liquids and gasses. You hit the nail on the head with this one.
@@Uryendel yea there's a bit more meat to them but you also have quite a bit of surface area with thread engagement which is what gives threaded caps their strength. i know it's not the best of comparisons but there's some similarities in function.
@@ToeCutter454 It's not just there more meat to them, they're designed to fail in a safe way. The RN-50 would be fine if they made sure that the cap was stronger than the barrel (either by having a stronger cap/locking mechanism or a weaker barrel)
@@Uryendel That's an interesting idea, but if the barrel blows up on a rifle like this it's still gonna do very similar damage to the shooter, I wouldn't call it "safer" by any means
@@phalanx3803 yes, and that does help eliminate hostiles. There's a minor problem, the angry binary noises coming from the local techpriest at such a ancient and revered weapon being so mistreated.
10+ years in the industry…seeing an owner respond like this is porn. Truly amazing to see you come out and set things straight with facts. I need to buy your stuff now 👍🏻
We colloquially use "failsafe" to mean cannot fail, but that's not what "failsafe" actually means. It means that when something fails, it fails in a safe way. Usually in the form of an intentional weak point. I'm not sure how a failsafe could be designed for this problem. As you point out, simple case vents aren't going to do much.
@@muwuny Did you watch the video? Did you listen to the words that the man said? Did you understand what the words the man said meant, or not-even-close? Because ^The Evidence^ here would suggest at least 2 "No"s in answer to my questions, but hey, you keep-on trying to talk to the grown-ups if it makes you feel clever Buddy... 😉👍
@@muwuny you know what the weakest point in a firearm HAS to be? An unobstructed barrel. Any other weak point and explosive pressure will find it. Maybe not on the first round, or the first 500, but eventually that "fail safe" will fail when it doesn't need to and cause issue. Pressure will follow the path of least resistance, so if that less resistance is anywhere other than pushing a projectile down a barrel, then you don't have a firearm.
@@muwuny You're dealing with pressures at 300% of the pressure rating of a .50 bmg cartridge; More than 180,000 PSI. There's no way to make that fail safe, anything releasing that much pressure in any direction other than away from you is going to end badly, usually very. That energy is going somewhere, and if it's gotten to the point where the equipment starts failing, it's usually everywhere. When you're dealing with extreme equipment, safety is usually managed at the individual level, not the equipment level, for the simple reason that, under extreme circumstances, you just can't get something to fail safely. Precautions need to be taken, safety needs to be considered at every step along the way, and both of those need to take priority over anything else. Simple fact of the matter is that Scott got a bad reload. A very, very bad reload. There's no accounting for rounds that operate at near 400% of conventional cartridge pressure, that's like taking a hair dryer and hooking it up to high voltage lines. And when failsafes aren't really an option, the only thing we can do as a community is learn to take precautions, to consider safety more. Because in the end, Scott fucked up. He didn't _know,_ he couldn't have... But there's lessons to be learnt in every accident, and i don't think the lesson to be learnt here is one that we can simply push off to engineering, and wish them best of luck with it. This one's one we can all learn from. And for the record, _no rifle in existence has a 4x operating pressure failsafe, quit the vindictive bullshit._
Admittedly, I was one of those suspecting a design flaw when KB blew himself up. For me, it felt logical that when a gun fails, the mass between explosion and the user should be as big as possible and some obstructions (like enclosures) would reduce the force of shrapnel in case something goes wrong. It´s logical that the "ears" that were sheared off were the almost lethal parts that punctured scott. Thus, I found the comparison experiment with the M2 really good as it showed that this really doesn´t change things for the better, but adds other random factors to the issue. But that´s all besides the point. The gun blew up because the ammo was tampered/faulty and any gun would have blown up. As soon as the gun blows up, it´s rolling the dice if shrapnel goes your way and where it hits you. The "ear" could have missed or it could have punctured the skull.
Well said. Basically spend an extra 8k for a freak failure to be a bit safer… If can avoid the problem shouldn’t need the extra safety I suppose. Cost vs benefit.
@@carsonhunt4642 reminds me of ww2 german tank overengineering, i mean the designs were good and all ¿ but did they really need to add so much complexity and extra features when it would work just fine with much less? i really like their tanks and i can easily see they made a massive amount of bad decisions. Tho those bad decisions are one of the biggest reasons why i like learning about engineering in wars
I argued the strength of the rn50 for several days after the incident... a whole bunch of people saying "I'd never buy one of these pipe bombs" and then I broke down the numbers for them & pointed out the fact that they would've never put down a deposit on a RN50 to begin with, so that just leaves more for the rest of us... 🤷♂️ Thank you for doing all you do, Mark.
@@rsh4599 that pressure max is so crazy to think about. If anything u would think that ppl would know it is a good rifle becuz it took over x3 the pressure to blow it up. I bet none of my firearms could take 3 times the pressure.
It is pretty obvious from Scott's recent video finishing the last of the ammo box that an improperly loaded round was the cause. I recently blew a 7.2 ounce muzzle brake off a gun with experimental sabot ammo. It simply sheared off the thread adapter and went downrange into the woods somewhere. Recoil was normal with no damage to the receiver and no appreciable case head expansion or case pressure signs. It actually took a few seconds to realize what the downrange noise in the woods was and that the muzzle brake was missing. We can usually tell a lot from examination of what remains. Scott's experience was clearly an over pressurein the chamber event.
I was initially in the sabot vs break camp, but I was in a gun store and had an epiphany. I was staring at a pre-WWII Reminton Auto-5 with a Cutts compensator. Shotcups are a lot like a sabot. Even if you were a royal fudd like my grandfather, who used a fiber wad and no cup for black powder skeet loads (sorry ghost of Gramp George, no, no, no, oh hell no), then you're really making it worse by shot column vs comp. We've been putting comps on shotguns for a century. If this was a problem, we wouldn't have noticed earlier. The only answer left is ammo, and bleed off holes for a 50 are going to be closer to a cutting torch than anything.
A break will never make a gun explode unless there's some reason the barrel has been completely obstructed lol, pretty sure that KB would have noticed this and whoever came up with the idea is an idiot
@@DickCheneyXX the argument was the sabot plastic clogged up the muzzle brake. problem is if that was true the muzzle brake would blow off not explode at the chamber
@@iceman5117 also the claim that slap shouldn't be fired through a brake appears to be nothing but Fudd lore. the guy knows the President of Barrett so if Barrett ever said anything he would know it. it takes a number of slaps to go through vehicle armor and hence a machine gun is far better for that then a ten round semi auto material rifle.
Scott from Kentucky Ballistics did a test with 3 rounds, the first with a normal powder charge, the second with a 1.5 times powder charge and the third with a heavy double powder charge. It was the third round with the heavy double powder charge that blew up in almost exactly the same manner as the first RN-50 that almost ended him. Scott followed up with a second test with a new RN-50 and a new round with a heavy double charge. Again the results were almost identical to the first one that blew up on him and the first test rifle. None of the rounds he used for the tests were Sabot rounds to eliminate that as a factor. His conclusion was that he used rounds which he could not verify were factory loads. His new policy now is to only buy rounds from sources that he knows and trusts. It wasn't the gun that was faulty, it was in fact bad ammunition.
Well said. It's like putting a 400 shot of nitrous into a 4 cylinder grocery getter. Even if you can get it to not extinguish the plugs, it's not going to last very long.
this doesnt change that the RN50 has unsafe points of failure, the cap is its main weakness and any failure in the cap will result in it being tossed at the shooter as shrapnel, an easy way to fix that would be to design the chamber walls such that they were still strong, but weaker than the cap, so that any round loaded normally still fires normal, but dangerous overpressure would rupture the chamber walls, venting pressure to the sides, where, on a safe range, noone should be standing
The amount of people who don't understand that a bolt action is just interrupted threading is astounding. And that complete threads are going to be stronger.
I didnt know anything about that and i also dont have any thread knowlege. That being said, without any knowlege of that stuff, i always though a bolt action was safer compared to that breach cap just by the look of it. Its like judging a book by its cover, its ok to do it but don't go around spreading potentially miss information about the subject to anyone.
Depends on coarseness and depth of threads. Yes artillery is interrupted thread breach but very coarse and deep. A bolt on bolt action even one with 9 lugs is not interrupted thread it is similar but not interrupted thread. And much stronger than medium to fine solid threads.
I'm actually convinced that the cartridge which injured Scott was *in excess* of 200000psi, because even the rigged cartridge meant to obliterate the rifle in his test couldn't do nearly the same damage. Looking at the test rifle also championing through the rest of those SLAP cartridges before that actually inspired a lot of confidence in me of the screw plug breech, because you've got those _crazy high_ pressures with most of the cartridges seizing up the breech something fierce, extraction was a project almost every time, and still the gun didn't blow or even so much as burst or bulge the barrel. I'll be frank and say that the RN-50 isn't a dream gun for me, but I'm also convinced it's an extremely safe rifle, few other guns on the market would tolerate the nonsense conditions it could go through here. I mean, will people call an antique Colt 1873 a death trap because you can Elmer Keith the thing with smokeless handloads? I wouldn't, and those guns aren't even drop-safe.
I think in many ways it's an awkward rifle, if money wasn't an issue I think it would be an odd choice, but agree that it appears to be very rugged/overbuilt
@@Wehra96 There's a lot of different things which could have been wrong with it. The powder could have degraded from bad storage conditions _(and according to some, these SLAP cartridges used a different powder from normal .50BMG ball which was less shelf stable, however true that claim is),_ along with it potentially being a counterfeit made with something like pistol powder, which itself could have degraded. Some suggest that it was a salted round, like Project Eldest Son, but I find that be less likely. Being a Cold War spy project thing, and such a specific one at that, it seems to me that it would be odd for it to pertain to a .50 BMG SLAP of all things, something which never got around anywhere with any enemies of the US or NATO, and then that cartridge would have to make its way back and onto the US. I really think that it's either a counterfeit which wasn't expected to be shot, or that it was a genuine SLAP but which had its powder charge degrade one way or another, the odds are just far higher.
@@tedarcher9120 using ears as safety check to ensure breach is closed would not work if you had essentially a quick change interrupted thread breach cap. Or you’d need to much more tightly tolerance the space between rear of cap and ears, which could interfere with the closing of the gun. A workaround I could see is an indexing detent on the cap that would only allow the gun to fire if the cap is rotated to the proper location, but then we are talking a more complex safety mechanism than just making it so the action won’t close until you have adequate closure of the breech cap.
I still feel that the rounds that were used were overloaded and dangerous. Too many people love to use heresy and innuendo without actual proof or facts, especially on the internet. You know what you're doing Mark and you stepped up from the beginning. I'd buy one o your 50's................ If I had the money, lol. Seriously, thanks for all of the videos you've put out and for addressing everything. Stay safe.
It's funny Mark mentioned being less safe by trying to be more safe. The 1st Generation Dodge Viper is kind of an example of that. Back in the late 80s, there was no traction control system or stability control system. The driver's right foot was the traction control system. The driver's hands on the wheel was the stability control. The 1st Gen Viper had very wide tires for the day (and they're still wide today) in order to give it lots of grip for that monster of a motor it was carrying. And it worked! The Viper had a ton of grip, but it was also kind of a problem. You see, you could use all that power and get going really fast indeed, but it also meant that once you crossed the limits of traction, you were going really freaking fast when it did let go and chances are that most drivers didn't have the skill to bring the car back in line. Issac Newton was in the drivers seat at that point and you hoped that Chrysler's engineers built a safe car, because you f***ed around and were about to find out.
having spent several years driving an early viper I can tell ya that when you finally exceeded the grip / handling limits - there was lots of flailing arms, swearing and sweating and the eventual change of underwear and stiff drink hahaha , that car forced you to concentrate 110% of the time when driving it, even if just popping to the shops... But it was such fun and a very rewarding car to drive, even if my ears didn't agree with my choice of straight thru side exit pipes >_
One thing that I've wondered since then: if the threads had held for that round, what was the next failure point? Imagine if it was fragments of the firing pin assembly, heading straight back through the shooter's torso?
@@wilsonrawlin8547 It's also possible that, with enough pressure, he could have simply split the barrel back by the action. Which would have had a nearly identical effect.
Absolutely right. There’s no way in hell the sabot would get stuck enough to blow up the gun under normal pressure. People who believe that are probably thinking about guns in movies, or those old-time shotgun barrels made from fused sheet metal. Modern, proper firearms made from quality materials are really brutally hard to create a barrel obstruction severe enough to blow up the gun with. Threading the inside of the barrel and screwing in a 2-inch bolt can do it, but less than that is unlikely to make any difference. I’d shoot the RN-50, no qualms. As long as the ammunition is verified as standard-issue and within tolerance of the weapon.
It’s definitely written in military manuals and other manufacturers 50cal. Manuals for a reason. They usually don’t just scribble in “beliefs” in those things.
@@brianjames8600 Be specific. Exactly what do they write; “Don’t use sabot rounds with a muzzle break” or “Using sabot rounds with a muzzle break can obstruct the barrel enough to blow up the whole gun”? Because there’s a difference in intent and breadth of consequences. Do you have these manuals and instructions handy to quote them word for word? If you can, please do, as it would be interesting to see the way they formulate it.
I own a Mark Serbu designed 50A rifle, I’ve had many conversations with Mark and his staff, smart people, great accuracy and I shoot my own reloads. 3 rounds touching at 300 yards. Hang in there Mark, this to shall pass.
As non-native English language user: I always thought that "safe" and "failsafe" are 2 quite distinctively different words. "Safe" doesn't fail, "failsafe" fails but in the most safe way possible. Maybe I am wrong, maybe I'm making a mistake of translating English term back into my language and then searching for its meaning.
Something being "failsafe" means it's highly unlikely to fail But HAVING A FAILSAFE means having some sort of backup for when it does fail. I fully understand how this is confusing
Yeah, a failsafe device or feature is designed such that a failure results in what is most likely to be the safest state available considering the failure. So, for instance, at least one set of brakes on large commercial trucks and on railroad trains are designed to apply if air pressure is lost, rather than being unable to apply the brakes. Obviously, there will be situations where this isn't ideal(a single drum losing its air supply and overheating and starting a fire, for instance), but it is almost always better than the alternative of all the weight rolling freely. Another example is a lot of nuclear reactors will drop their control rods in place in the event of a power failure or if the control system detects issues with the coolant system, thereby slowing the reaction to a crawl and greatly reducing the risk of a meltdown. While there are probably a few situations where this would be less than ideal, I'm struggling to think of any atm.
@@1stCallipostle The OPs interpretation is correct - something that is *designed* to "fail-safe" is precisely that; WHEN it fails (failure is always an option), it *should* fail in a safe way. But reality doesn't always agree with your design. Something that is safe cannot cause harm; if it can, then it's not safe, *but* we do often use "safe" to mean "very low risk". (E.g. "safe driver" - driving is inherently dangerous.)
@@spudgamer6049 and that's more or less what the ears are for on the RN-50. He designed it to take like 150 percent of rated pressure and the amount of force to SHEAR those off is incredible. The powder obviously burned far too quickly so he had a small explosive in the chamber.... ouch.,
@@ExarchGaming I disagree. When/if the design fails, it fails in a fairly bad way. It just is designed not to fail except under extreme circumstances. That's different than being designed to fail in a safe-ish way. Not saying there's anything necessarily wrong with the design. You can only realistically design for what is within the reasonable realm after all, and I'm not sure that there are any particularly good ways to make a 50bmg chambered gun fail in a relatively safe manner that doesn't compromise it in other ways. Maybe those ears could be made strong enough such that something else would give before them, but I'm not sure how heavy that would make the gun, or even if that is realistically possible.
The whole "sabot plastic is getting stuck in the muzzle break" thing is easy to disprove. Just remove the muzzle break and try the same thing again. With the same load, the gun should blow up "just fine" without the muzzle break.
Pack the barrel as tight as you possibly can with discarded sabots and fire the weapon. I would fire it from the hip I am so sure nothing would happen. Teh problem was bad ammo. probably leftovers from project eldest son.
The most succinct, informative, and in my mind definitive review of this KB was done back when it happened on a channel called Backyard Ballistics. Despite the name, the guy is an educated professional firearms examiner tasked with gun crimes & failures. Right off the bat he said that just the threads being sheared showed it was the ammo and not the gun design. He explained several other aspects, like how a failed case will greatly increase bolt thrust, hence his recommendation for gas vents, why low-cycle fatigue is ruled out, and a lot more. Highly recommend anyone interested - you too, Mr. Serbu - check his two vids on the subject.
Just throwing this out there for some food for thought Mark and curious watchers. When I was in combat in Iraq we got tasked to actually implement spiked ammo into the battlefield ( enemy ammo calibers of course). It's a highly effective way to have passive attacks on the enemy, break up enemy moral, break up enemy supply trust, etc... As far as I know our RIFLE ammo never was spiked enough to kill but meant to destroy the weapon first, and have slight secondary injuries just as a bonus. Most times just a destroyed AK, RPK and some scratches and cuts on the hands and face/ eyes. We did have lethal stuff too but that was for mortar and artillery shells that got used for making IED's. Those weapons were tracked and could be detonated on command (very interesting tactics can be implemented with these babies). When you start talking bigger caliber rifles and machine guns like DShK's and NATO .50's there really is no safe way to destroy those weapons without making them highly likely to kill the user. It just is what it is...Make no mistakes about it though, the enemy was doing the same thing to our ammo. Hardly ever happened to americans because we hardly used battlefield pick up weapons and ammo. It's very easy to use this tactic on guerilla elements because they use what they can get most times... Saying that, there is alot of people that re sell weapons and ammo from conflict zones where these tactics are being used. Unless you are apart of the team that spiked or left the ammo on the battlefield theres not a great way to inspect and know which ammo is spiked and which is normal ammo... I would recommend never buying boutique ammo off of sites like Ebay.
I call BS on your whole story. This is the first time I've heard of the US doing this since Vietnam. And who in their right mind thinks you can buy ammo from eBay?
I'm glad this "rebuttal" has FINALLY come out. Thank you Mark for putting it in perspective and leveling the field of commentary. I laud you for your intestinal fortitude and telling the facts regardless of "popularity".
Scott himself said that it wasn't the fault of the gun. The really hot, overcharged ammo (presumably tampered) was absolutely at fault. Threads like that do not fail unless you seriously overpressurize the chamber. He just got super unlucky. Anyone claiming that something got stuck in the muzzle brake is wrong and clearly hasn't watched Scott's follow up video when he re-tried the test. He went through all 12 SLAP rounds and it didn't blow up. It took a round that he specifically massively overcharged before it actually blew up the gun.
@@toomanyaccounts correct, they're all kinds of counterfeit slap rounds and the way to identify them is they do not have a crimp, their primers are usually brass colored and not nickel colored like real ones, fake ones usually do not have the primer sealant present like the real ones do, and on the Sabot, fake ones do not have the little cuts on the top to aid in splitting apart to release the projectile.
As a machinist and someone who has worked on all types of metals for all sorts of things, I know for a fact that cap is no joke. I also know whatever can blow it off is no joke too lol.. Lot of guys here and on KB's comments who obviously have never worked on any metal in their life trying to act like they know everything about threads, metallurgy, pressure loads.. I'd ignore it. Like you said, too many people here just want to be heard and want to pretend they're better than someone else for personal brownie points
For the most part the cip proofing actually helps you as the manufacturer. Since every gun has to be proofed, if it blows up in consumers hands you're not really legally responsible at all. As the manufacturer you can say "it passed cip proofing, so whatever made it blow up wasn't there when it left my factory. If a gun blows up during the proofing, they'll basically just send it back and tell you to check if it's an issue qith just that example, the batch or the product in general.
2,000 rounds through my BFG50 and I couldn’t be happier with the platform. Mines in .510 DTC so the ammo is all handmade by myself and therefor far from perfect which should expose any weapon short coming quicker than more consistent ammo production processes. Thanks for what you do for our community Mark!
Mark your a good man for deep diving into Scott's accident! IMO I believe almost everyone believes that the round it's self was incompetently and egregiously overcharged with powder I believe that you provide a phenomenal product and that the accident had nothing to do with said product but you are good man for your diligence sir!
I think Scott proved that pretty conclusively when he (the madman!) fired the rest of those rounds in a much later video. Those were definitely spiked rounds.
@@reliantncc1864 What's the saying about Marines? Put them in a room that has no doors or windows with a steel sphere for 24 hours and they will have broken the sphere, lost it, or impregnated it? Something like that. (Not hating on Marines, just a joke.) Doesn't matter how "safe" something is made, some idiot will find a way to unsafe it.
I just want to say that seeing the way you reacted to this freak accident & the amount of time dedicated to figuring it out has made me want a Serbu more than ever! RN-50 will likely be the first 50 I get. Products fail at some point, it's impossible to realistically prevent. How the designers of those products react to the failures speaks FAR louder than any durability test in my book
I have always doubted the "plastic sabot stuck in the muzzle brake" theory... Plastic just simply cannot hold that kind of pressure without giving way.. I have seen copper bullets of the entirely wrong caliber get swaged through a rifle bore without any damage to the receiver or bolt... I still think those s.l.a.p. rounds were loaded with too fast of a rifle powder.. Or a pistol powder... Pistol powder in a rifle will cause big problems!! But that's just my thoughts on that situation... Love ya Mark! Keep em coming!☺👍🇺🇸
Pistol powder in a rifle is great for cast bullets. But it's also way too easy to overcharge a case with the tiny amounts of powder that are used, so you have to really be paying attention while you're loading. It's possible the same kind of thing happened here - they used a regular rifle powder when a slow-burning magnum rifle powder was needed, and ended up doing a double or triple charge.
The genius physicist/ metallurgist/engineer ,Matt at CRS firearms , jumped on the "unsafe" design band wagon and even showed in his "expert" what you should have done.
@@cberge8 I also unfollowed that douche nozzle because I can't stand people who know absolutely nothing about a particular subject , except for a Google search ,then give"expert" advice on that subject. It would be like giving a brain surgeon tips , because you watched a film in biology class about the brain. Matt's apology was a hollow gesture and CYA. He used his platform to trash a Guy and his product , that he knew ABSOLUTELY NOTHING,about then say ,oops my bad ,sorry.
Those stating that the muzzle brake was involved should contemplate what happens if you plug the muzzle with mud - or even better: You could demonstrate what happens by welding in a steel plug in at the muzzle; then firing a shot. Measurements for the barrel diameter at the breech, before and after "dynamic clearing of the muzzle obstruction" should count for something.
The concrete Sarkissian obstruction probably already shows the principle. Without the before/after measurements to prove zero extra stress at the breech.
Mark, Indeed it was bad what happened to Scott. Love both of your channels. When I watched Scott's video of the Rn-50 blowing up on him. Not once did I say the gun was at fault. Myself, I am not an engineer, Yet I am a mechanic that hunts and reloads. Lot of experience with things that goes boom and blowing up stuff also. The very first thing I thought of was, That round was over charged by or with the wrong powder. Or it being old, the chemical change with time made the powder a lot more volatile than normal. Also, for the record, I do have a place set aside in my gun safe for an RN- 50. Just do not have the land yet to fire one.
I'm glad you are talking about this Mark, I've loved your weapons from afar as a poor Canadian. I have nothing but trust in your commercialized designs and wish I could buy them. One day, I'll own your BFG, and your RN50, but again, thank you for talking about how your RN50 works and what went wrong. Especially for giving Scott another one to blow up.
Hi Mark, it's very obvious this matter has been troubling you greatly(understatement). I have know dought and believe totally every word you say about your chosen profession ie gunmaking,, I would purchase an rn from you everyday but sadly we don't enjoy the same freedoms you all do and we aren't allowed in the uk. Good luck to you sir and great vid! Be safe. 👌👍👏
There are some UK shooters who use .50 BMG long range target rifles. UK law does not ban them outright but expects users to apply for an FAC and show a good reason (eg target shooting) for owning one.
It’s so cool how much responsibility he takes over this even though it wasn’t really his fault. He wants to make sure this never happens again. To anyone.
Mark Serbu is basically living my dream; I'd love to start a gun manufacturing company. I respect the hell out of a man that can put controversy aside to address a problem like this one. The KB incident was a clear case of faulty ammunition and not a design failure of the rifle. It could be interesting to design a new rifle that could stand the pressure of one of these rounds going off.
"Fail-safe" does _not_ mean "cannot fail" -- it means that _when_ it fails, the failure mode will be SAFE (rather than dangerous). One well-known example is the "crowbar circuit" which creates a short circuit to force a fuse to blow in order to prevent catastrophic damage to the power supply when a failure occurs.
some people seem to use fail-safe without considering its meaning, they may mean the chance of a failure or unsafe condition is exceedingly unlikely another good example, glider training operations. the braided kevlar tow rope always had two weak links made of poly rope, if a strong thermal comes, truck is too fast or the pilot is climbing too much, or somehow the glider cant pop its release. weak link pops and prevents airframe, tow vehicle, or expensive haul rope damage, and just becomes a small pain in the ass for the pilot to modify his flight, and for me chasing the rope through the swamp.
Exactly! To Mark: As an engineers we want REDUNDANCY in safety measures, that is what "fail safe" means. Measures that are destructively tested to prove they work as fail safes (aka redundancies). Personally you should probably listen to "gun jesus". He just might have some knowledge you lack. Screw caps are barely considered adequate on sub-guns, much less 50 cal bolt-action rifles. And the whole "heat treat it, yeah..." comment.... for F's sake hire a materials engineer and/or metallurgist if you make a 50 cal Bolt action. Don't tell us "heat treat it yeah..." And larger, more-secure "bigger things" (i.e. safety mechanisms) "flying off" would "fly off" exponentially slower... and would not "cut your head off". No ones "trolling" this man, but he sure loves to blame the internet when his gun blows up.
@Hornet135 Of course it can never be 100% safe. But it will significantly improve safety by a magnitude. Look at crash tests on cars. Imagine if they gave up in 1930 and just said "fuck it, car crashes occur with too many variable let's just give up on making cars safer." Instead they made fail-safes called crumple zones, which Ian says is similar to the arisaka vent holes and safety cap which are made to redirect energy away from the user. With enough energy of course these safeties will still hurt the user. But now you need a hell of a lot more energy to hurt them.
I will reiterate: My opinion, as an experienced, trained engineer that also shoots... Is that Mark's design is solid. Accidents happen, and I believe the ammunition caused this one. I don't see where suing Serbu is beneficial to our hobby.
I think that the gun may have been i micro bit weaker than the new one since he shot it before but it would be neglible. So all the fault was on the slap rounds. Sry for bad english im a swede.
It’s obvious it’s the ammo but the gun design fails catastrophically for the user. No other 50 on the market would fail so dangerously given that same round
From my engineering armchair: you don’t need to make it stronger you need to make it weaker. You want the RN50 to fail in a way that would send shrapnel down range. Add flutes to the receiver to make it weaker then the bolt cap - that would be failing safe. What you described as fail safe was a design that would never fail. Keep up the good work Ps I don’t believe this was RN50’s design is at fault but every design can be improved.
awful idea. That sounds like a great way to turn an action into a hand grenade because you're purposely giving it weak points to break apart at. The gun as built can handle proof rounds all day so it's plenty safe for the designed operating parameters plus a safety factor. Buy trustworthy ammo or load your own if you know what the hell you're doing.
Exactly. Fail safe means that when it fails, it fails in a safe way. It does not mean that it never fails. IMO, the problem with the RN50 is not the threaded breach plug, but the two support lugs behind the breach cap. In both explosions on KB's videos, the support lugs became lethal fragmentation.
@@mckennaConfig The lugs probably slowed the cap down enough so it didn't just go through his skull. If I remember correctly, it hit the lugs then went up and hit his safety glasses, which also probably spread out some of the impact, and it still broke his eye socket in a "glancing" blow. Being hit by it straight on would more than likely killed him.
While the RN50 isn’t for me, I absolutely love the fact that there is a 50 out there for people who couldn’t otherwise afford one. I personally wouldn’t blame the gun for a freak accident. Especially when the guy who got injured by the gun proved it by recreating the accident and still uses the gun to this day.
He does hide behind the truck more now for sure. Lol! He still shoots the RN50 from his shoulder though. Granted he cuts in the atom bomb explosion every time now.
The only thing I can think of with the army not wanting to use a brake with sabots would be from the experience gained with the 76mm or 17 pounder from WWII, where the brake interference on the proper release of the sabot severely impacted the accuracy of the weapon. Plenty of notes on that throughout the internet. It should be an accuracy thing, not a safety thing, not sure why people immediately hear of the military saying something is bad and always equating it to “Oh, so that means we all die”. Anyways, great video, sorry you have to deal with a bunch of idiots talking shit about your products. Fuck those people.
The 17 pounder was inaccurate due to the Sabot being a new concept for the British army at the time, and it was fixed after a while. Crazy speeds (for the era) coupled with "detaching" part of the round itself... Btw, 16 pounders haven't been used since the early 20th century.
@@nikola12nis Mistyped on the gun size, but the idea is there. However, even the Tank Museum at Bovington has commented on the muzzle brake impeding the accuracy of the round. We also see that the 90mm guns from later on have similar issues and why modern tanks and guns that use sabot ammunition don’t use brakes.
In their defense.. when the military screws up.. they tend to hide it and thousands of people do get hurt. Think the VA. But it's not from target shooting. 🤣
Occam's Razor: The overloaded round was the most obvious choice. The goal of smokeless powder design is to have the burn continue for the length of the barrel so you get acceleration the whole time. The psi lowers as the round moves further down the tube (somewhat depending on grain burn rate). Barrel taper and design of the reinforced base of the round lead back to that initial max pressure being found before the round even leaves the crimp. To me that shows why the barrel exploded back and not somewhere near the brake.
@@randomidiot8142 black powder that is true. Smokeless powder keeps the burn going longer. That is why rifle powders and pistol powders are different. You want the heat and expansion to continue. That is why modern guns shoot so much faster and why for some calibers longer barrels don’t help velocity after a certain length.
@@randomidiot8142 No, smokeless powder continues to burn while the bullet moves down the barrel. Depending on the ammo and barrel length, you may not get complete burn of powder. This is why people argue about what barrel length is best for certain calibers. It's also why you lose velocity when you shorten barrel length, bullet is in the barrel for less time meaning you get less powder burn. It goes the other way too, if your barrel is too long you'll lose velocity, because you'll get 100% powder burn, but the bullet still has more barrel to travel and that just creates more drag on the bullet and you lose velocity. You mostly see that in .22lr because the cases have so little powder in them but it still happens.
The idea that a screw connection is "weak" is laughable. Threaded connections are some of the strongest non permanent mechanical connections it is possible to have. Threaded connections can apply and hold LUDICROUS forces. The same person that suggested a threaded connection is weak, was probably on the same level of intellect as the person who asked "is there a way to make it so that NOTHING could blow it up?". The answer is, of course not. Why? Because the list of shit that you would have to make the weapon proof against is huge🤦♂️ and contains some of the most potently destructive chemical explosives, like RDX, C4, Det cord, and THERMITE! I don't care how thick your barrel walls are, how chunky your receiver is, or how dense your chamber is, if someone sets off a chunk of thermite in it, it'll fucking melt. If they light off some detcord, or set off an RDX or C4 charge in there, something is going to go pinging off in an unhelpful and dangerous direction. The only way to make any firearm safe is to establish upper working limits for chamber pressure and ensure the tolerance of the part exceeds all the most likely loadings in the caliber involved, while designing the object to fail in a manner that is least likely to result in injury. No one expects or ought to design around loadings that are inadvisable to begin with, like putting grenade like overpressured rounds, into a weapon system that was not designed to handle that pressure. The issue was with the round being spicier than taco Tuesdays farts, not with the gun being too weak. I'm not even a gun guy, and I know this. 🤦♂️
Odd that you would jokingly belittle Royal Nonsuch at the beginning for “shitty welds” (1:00) while the firearm being reviewed is a RN-50. I do appreciate your channel Mark very much. You are a patriot. The same test with overloaded rounds on a Barrett 50 would prove the RN-50 design safe in my mind. If a military proven 50 also blew up. Not a cheap test though.
Kentucky ballistics already detonated a barrett .50 with a overloaded round, using the same test load he used to detonate a second RN 50 (which had the exact same results as his accident gun). Spoiler; it was destroyed beyond repair.
@@larryclark9380 No need to look. Here it is: ua-cam.com/video/xRufSjBtJNE/v-deo.html He's done a whole series of blowing guns up for science since the accident. It's really worth it to watch all of them.
If people lost faith in the RN-50, you'd see a ton for cheap on gunbroker. The fact that you DON'T means the owners out there still have complete faith in the weapon they've been using. And aside from Mark, the next best source of experience with the RN-50 would obviously be it's owners and users.
You fail to notice that the existing gun owners are not the only place where you can measure the effects of it. There is also the market for the people who don't own the gun yet, who might have considered but now backed away from purchasing one. That is something you don't see unless you got your hands on the marketing and sales data. To my knowledge, Mark Serbu hasn't disclosed the data but the way he's talking about it might suggest that his sales have gone down due to the speculation on the gun's safety.
@@anteshell then there are people and lots like me who want one even more now. The fact if took that much to hand grenade the action has me even more confident in its abilities.
@@larrypostma2866 that is certainly possible too. I tried not to make any assumptive statements. Rather just speculating about plausible consequences of this ordeal.
The only thing I could think of for making the firearm more "fail-safe" is some sort of shroud over the lugs as a buffer between the shooter and the lugs in the event of a failure, obviously you'd have to figure out how to cock the hammer with it in the way (have it flip down and latch perhaps) but something as a buffer should drastically reduce the energy imparted into the user of course modifying the firearm could go one of two ways in the publics opinion, it could be seen as an admission that the design wasn't robust enough to begin with or it could be seen as a good faith effort to make an already well built firearm even safer, I think the result would just depend on someone's current viewpoint so not much would change
It's just amazing to me how people can say "Oh the gun was definitely at fault" when as long as I've been in the online gun community, the RN50 has been around and this has NEVER happened before to a single person. Meanwhile, overcharged .50 rounds, especially of the more exotic varieties are an almost common occurrence
Fail safe doesn't have to mean 18.1" battleship barrel. It could mean a deliberately weakened section that will fail first and direct the explosion off in a safe(r) direction. See the blow out panels on the M1 Abrams main gun magazine. Unsure how you'd design that into a firearm like the RN-50 without massive compromises.
While i agree with most of your points, I interpret 'fail safe' very diff - to my understanding it's not about the 'MARGIN of safety' or 'WHEN will it fail', rather 'HOW will it fail' In other words, sure it has more than enough safety margin under most use X5, but what will happen when unexpected/edge case (e.g. bad load) use causes a fail? example would be casing/difflectors that would direct most (and especially bulk/heavier) shrapnel away from the user crucial mass (which would be the direct cone behind the gun). This design principle can be seen very far back in firearms design imho.
@@franklinAll8735 agreed. and the more i think about it, the more this vid feels like a strawman, as even wiki definition clarifies it as "in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people." Moreover, using the footage from Scott/Edwin, brings to question was the RN50 ever tested to simulate overstressing events? or just proofing it against max stresses? simulating failure should be part of any risk bearing design and manufacturing imho. Edit: I think a better answer would be 'define your risk appetite, but this is the only way of producing a Reasonably Safe device, in a Reasonable Cost' - completely acceptable reasoning to me.
I've read of armies tampering with ammo supplies by adding high explosives to enemy's ammo so they intentionally destroy rifles. but I think you're done all you can for your product. it's nice to see you standing behind your product.
that has never been done to nato rounds. it was always done to commie block ammo. counterfeit slap rounds are known to exist. it isn't some foreign intel agency its bubba doing the feits to make money
The only difference I can see in regards to “blowing up” a gun is how the energy is dissipated.. In the case of the RN…once failure is achieved, essentially some of the parts become projectiles directed at the shooter…. In the case of the Barrett, the top frame helps “shield” the shooter from fragments…though you would likely still sustain a gnarly slap to the face…. Think blast shield on a revolver…though the cylinder may explode…the energy is directed away from the shooter…. I believe this might be the purpose of the “vent hole” in some designs..it causes a failure point to direct the blast..in an attempt to prevent the bolt from sheering and being directed into the shooter….
This. I wish he'd addressed that. Just because you can't make something fully fail-safe doesn't mean that some designs aren't more failsafe than others.
When the incident took place I immediately thought of some of the secret squirrel shit we do to enemy forces in the wars we've been in. We purposely place overcharged, and booby trapped rounds in enemy inventories. We don't necessarily know who's going to use that ammo, just that it will kill them and lower moral. Any round that was overcharged like the one that got Scott, was purposely built.
Mark, how many of your critics have designed, engineered, and built a "safer" practical firearm? Yeah, exactly! Please keep building your excellent products. I'm ony one of your countless fans.
I think there is a misunderstanding concerning "fail-safe" systems. Tom Scott actually did a video on that called "Fail-Safe vs. Fail-Deadly". "Fail-safe" is not "safe from failing". It is "Safe even when it fails". So, with early bolt-action firearms there have been fail-safe mechanisms such as a step to redirect powder gas away from the eye if the cartridge blows out to the back. In case of the chamber failing, a fail-safe would probably be something like a chamber wall that is weaker than the threads, so the wall blows before the cap, or a sturdy catch that prevents the cap from flying backwards even if it shears off.
Yes, exactly. Look at the M1 Abrams. Those engineers rightly realized that they could not prevent an explosion inside of the tank. However, they did mitigate the worst effects of this failure mode by designing a blow-out compartment for the ammunition.
@@dbz5808 no, obviously you make it rated strong enough. You make one point relatively weaker that faces away from the shooter so if you did use dodgy ammo that part ruptures rather than possibly blowing out towards to user. Essentially you make the thing fail in a safer way in extreme circumstances.
@@CAMSLAYER13 Sorry, at the pressures we're talking about, and DELIBERATELY introducing a weak point will simply ALWAYS cause the gun to fail at that weak point. At the pressures we're talking about. It's simply asking "How many pieces of shrapnel do you want on your frag grenade"?
The only difference between the RN-50 and the Barrett is that when tested to catastrophic failure, the Barrett did so in a way that *didn’t* blow large chunks of shrapnel directly rearward at the user’s head. And I believe the fundamental design of the RN-50 won’t allow that to be mitigated in a meaningful way. It’s just the nature of the design. For the same reason that automatic/semiautomatic designs almost always fail more safely than bolt actions. There’s a moveable bolt with a spring behind it with several inches of travel before it bottoms out, all the dead space in the receiver to contain the blast of a blown up chamber, and a giant hole in the bottom (the magazine well) for gas and shrapnel to exit the gun. We’ve known this for well over 100 years. So why do we still use bolt actions? Because the situation in which they fail is so extreme that it almost never happens, and when it does, you can almost be guaranteed that it was due to extreme negligence by the user. The RN-50 is a safe gun as long as you don’t shoot boobytrapped ammunition in it.
I dont care what it is, u dont want 200k psi going off in any way a few inches from ur head. That barrett isnt rated to those pressures either, and at those pressure every part just makes a bigger grenade.
With the pressures we're talking about here, a semi bolt wouldn't have anywhere near enough time for the bolt to unlock before catastrophic damage occurred. I don't see how that would make any difference except to provide a whole lot more little pieces of schrapnel than a few monolithic pieces. But it sure sounds like a good idea for a video....
The Barrett also probably blew up before it hit the same pressure levels as the RN50 which means the shrapnel was less energetic. But this also means weaker loads of degraded/tampered ammo will still send shrapnel at you in a Barrett, whereas an RN50 might be ruined but intact. You could also be more confident in your own wildcats with an RN50
We know the barrel was not obstructed. So, I'm not sure what the shooter could have done that made it operator error. I have a very hard time believing the round that blew up the RN50 was a factory round. The most likely situation seems to be that it was a reload and the reloader made a mistake. The seller may not have even know it was a reload. If factory ammo was as hot as that round, you'd have seen news stories or field reports of machine guns blowing up. Now the failure might have been less dangerous. Because the machine gun is much larger and not meant to be man portable. But put a pipe bomb in a gun and it will go boom.
@@DeadeyeLefty kentucky ballistics blew up a barrett. it sent deadly sharpnel into the dummy. on a bolt action the entire bolt would have gone into the users face
Man I can't imagine having a company and dealing with an issue like this. With how people are so willing to internalize their first instinct and then dismiss anything that could challenge that thought, really fighting an uphill battle even if you are completely in the right.
I am not dismissing new evedence, but I don't think the owner of the company should be labeling potential costomers as stupid for asking more detailed questions.
You could have threaded the outside of the entire barrel and make a 33.41" long threaded end cap and that gun would have still blown up. Might be a fun project just to prove a point though!
Not an engineer but your analysis along with Scott's followup videos make it clear to me that the slap round was crazy overpressured and nothing but an adamantium action and barrel reinforced with vibranium could have survived it. The tribalism comment is 100% truth and continues to be to our detriment as a whole (as a gun community and as society ingeneral)
A similar thing happened to a factory 30-06 rifle with factory 30-06 ammo. It turned out the ammo and rifle were in the truck, on dirt roads, for 30-40k miles. The powder rids broke-up into a small flake size, significantly increased the burn rate. I believe this is what happened to the 50 BMG rifle using surplus ammo of questionable storage and transportation.
Yeah I remember when Scotts accident first happened I saw a comment guessing that whoever sold him the ammo was probably running them as whole cartridges through a case tumbler to make them look nice and shiny. Would love to see that theory tested.
the slap round that blew up Scott's RN-50 would have grenaded ANY .50 BMG rifle. Scott proved this in his own videos lol. i suspect it would even grenade a modern M2. i'd be interested to see ANY chamber that could handle those pressures. in fact, i think a purpose built canon that had a welded on breach would have to be impressively thick to safely fire that slap round. The more interesting question to me at this point is where exactly that slap round came from? was it one of the mythical sabotaged rounds that the CIA supposedly fed into foreign markets? Was it a hand load made by a half asleep moron? was it a factory round that got the wrong propellent somehow?
The term you're missing is failsafe. Compare RN50 failure with Barret failure. RN50 threw a cap right at shooter's face while barret did a decent job of deflecting the fragmentation upwards and sideways away from shooter's face due to its enclosed design aka receiver.
I agree that the round was way over pressure and that the rifle was not at fault. However, Scott's "test" was proved nothing. It was fun to watch though. All he proved was that an extremely overpressure round can destroy any rifle. It didn't provide any comparative data between the two designs or data on the original slap round in question. Imagine if i wanted to test two different beer can designs for strength so i dropped a bulldozer on each. They both get crushed so i determine that they have equal strength. Do you see the problem?
Could also be because of age. Some gunpower gets unstable after a while. (depending on storage conditions) I imagine that could be a huge problem on a round like this.
"Fail safe" doesn't mean "can't fail", it means when it does fail, it fails in a way that's relatively safe. I would be thinking of something that deflects or catches a broken part. Like in the barett video more of the energy goes into bending/destroying the receiver rather than throwing a loose part towards the shooter. But that is just a natural consequence of the semi-auto being more enclosed; I understand you have a high safety factor and shouldn't need this.
Yeah I’m pretty shocked Mark has misunderstood that term and concept so completely. Failsafe is great and has been in firearms designs for over a hundred years. IIRC Ian or Ian’s comments mentioning old Mauser actions having an intentional blowout point for overpressures.
He went on a tangent and explained it poorly, but I think he knows and that's what he meant. No system can fail completely safely from all possible causes of failure. The fail-safe itself is a system, that system has limits, and it too can fail. Put enough weight on an elevator and you'll see even the brakes won't hold forever. Case in point: when Mark talked about the ears, brittle vs soft. The ears are already a fail-safe system by themselves, for the threaded cap of the action. But then he considered what would happened if the ears sheared - so a failure of the fail-safe - and the consequences of hardening that part: it makes it less safe on failure.
I think the respect for the raw power of .50bmg gained from Scott’s accident was overall a positive thing, glad he is alive and well, and it’s unfortunate that you and your business have been blamed for what happened, by the people who are just there with an opinion based on little fact, the RN-50 is like a child of yours from a business standpoint. And a severely over pressure round would turn any man portable firearm into a pipe bomb, hell even a M2 would have failed catastrophically from something that overpressure, and that’s the gun literally designed for .50BMG, don’t let the hate out there get to you to much Mark some people just want to be angry at something because they can act like an expert and feel somehow validated by throwing shade at someone who literally engineers firearms for a living. Good on you for letting most of it roll off your back, never stop chasing your passion. ✌️
Hi Mark, appreciate the videos. I think more importantly than “fail-safe” is mitigating the worst effects of certain failure modes (FMEA). As engineers, we should be concerned with mitigating effects to operators given a particular failure mode. An example of this is the M1 Abrams. Those engineers didn’t pretend that they can prevent an explosion inside. Instead, they mitigated the effects of an explosion by keeping the ammunition in a blow-out compartment. Maybe there are similar steps you can take in future designs to mitigate the effects of the worst failure modes.
What you are describing, are fail-safe systems. Fail-safe does not mean fail-proof. It means that when a fail happens, it happens in the least worse possible way. Those blow-out compartments are fail-safe systems as they are supposed to mitigate the possible consequences by redirecting the blast force away from the crew.
As someone who does fail-safe electrical engineering (railroad), you try and make the failure mode as predictable as you can. For vital systems, we have to be one point safe - one component can fail, and the system does not result in loss of life (nuclear weapons are two point safe, and aircraft may have higher margins). You cannot always protect against a wrong-side failure (i.e. wiring defect, turning over a device to nullify gravity), but procedures safeguard that. It definitely is not as simple as making everything as strong as possible. Hardened steel on failure fractures into jagged pieces (and make deadly spall projectiles). A rigid cockpit in a car will transfer all energy in one jolt to the driver. That's why there is materials analysis. Crumple zones in car stretch out the force a bit, and absorb some of it. You want a power plug to pull out before the wires get pulled out of their insulation. Fuses are an example of a fail-safe. They won't stop an appliance from getting destroyed by a lightning strike, but they'll stop a zapped appliance from being a fire hazard if it was shorted by the event (for the railroad, lightning and electrical arcs are our biggest concern. We use carbon because it doesn't weld, and silver because it conducts the best in our contacts. We also use lightning arrestors frequently on top of that. Mechanical fuses are not unheard of. That seems to be the way to go if you can. Everything has to be stronger than the fuse link. There is a curve of velocity against mass here, where less mass can have more velocity. You might want to take a bigger amount of force spread over a wider area at a reduced velocity than a small mass high-speed (shrapnel) part. If you take a cable snapping as an example, there is a difference between letting it break in the middle somewhere as opposed to having it fail at the shackle or loop (an example is an elevator on one side of that cable, the cable failing away from the cab is better than towards it). Sure, it's not guaranteed to work if you run into a big enough idiot who uses it to lift a neutron star, but it's not hard to do.
my understanding of Ian's "fail safe" comments are as to how the gun fails. example, the ar15 is designed in a way that the upper receiver will blow away from the shooter when it fails. The Barrett being semi auto (& costing alot more money) failed in a much safer way with its huge plate sheild on top.
Not every weapon is that enclosed; a bolt action rifle would have sheared the lugs and sent the rest of the bolt back into shooters head. And AR style can injure people plenty with serious failures. If it’s overpressure enough to shear the lugs, bolt carrier can depart the back of the rifle into your shoulder. There isn’t an action that’s inherently safe. You can set a higher safety standard pressure to design everything to, say the 200k PSI of pistol powder in rifle or of an intentionally sabotaged cartridge, but you won’t enjoy the resulting gun sizes or weights.
@@steezydan8543 I’m confused what you’re saying here. .50 BMG is normal round maximum ~55,000 PSI proof pressure 65,000 PSI. 5.56 & 223 … is normal round maximum at 55,000, proof pressure 65,000. There’s less chamber cross section area so much less force, but that’s different.
When something had reached the muzzle break, the energy would have been spread and a piece of plastic wont hold any kind of force coming out of the barrel. Sabot rounds for 50 cal are only used on HB, you can find the people who were shooting tungsten with the M2HB with a scope with SLAP sabot munition.
Only thing I can think of is if in a Barrett a Sabot was fired and it left a piece of plastic at the muzzle end, then sometime after another round fired and it led to an issue, but even then, doubtful.
Certainly wasn’t expecting a mention… and I was still laughing at Edwin’s antics when it came up!
Anyway, re: the KB incident, if your previous videos didn’t convince people that your design will not fail under (anything approaching) normal use, I’m not sure anything will. It sucks that you need to defend your good name.
How unexpected. Nice to hear from you my family likes you're channel.
and KB did a video it as well and its seems a lot of people in the comments haven't seen it and KB did it with a barrett the gold standard of 50 cals and it blew up just the same.
You're up there with Project Farm in regards to trusted reviews.
I was surprised but you hang out everywhere
Whats up LPL. Good to see ya
One of the most telling things about this whole debacle is that I've only heard criticism of the design come from non-engineers. As an aerospace engineer, we don't design for margins anywhere near what you do, so when I hear that the action failed at 400% of the cartridge spec it's amazing to me that it got that far. Nobody expects you to be able to take a Honda civic and flow 10 kg/s of nitrous through the engine without catastrophic failure. Guns for so many people in the community are just strange magical blackboxes bullets come out of and God forbid if you remind them they are machines like any other.
Not an engineer, but when reviewing pressure tanks that exploded, the one part always intact was the threads. Just seemed like common sense that threads were always a stronger connection in pressure situations than lugs. Wish the so-called UA-cam-experts would have discussed that and shut down some of the hyperventilating about a threaded breech.
I fuind it amazing how the stoner ar design was great BECAUSE, a aerospace engineer designed it... imagine how great an airplane would have been if designed by a gunsmith?
If all guns were designed for the absolute max compressed load of the fastest burning powder available for the particular round chambered, you can bet the farm that the same complainers would be boohooing about how heavy and massively overdesigned the weapon is.
Why does my 300 winmag have to weigh 20lbs stripped?
On the flip side, thinking about consciously putting your face mere inches from an explosion with tens of thousands of PSI's of pressure to simply expel a small bit of metal in an intended direction isn't something that everyone really wants to think about.
@@jackdundon2261 You mean the A-10 Warthog? :D
A man almost died. Regardless of any factor, every single thing related to that accident requires in depth analysis. A lot of companies, once they realized they were clear of a lawsuit, wouldn't have given two fucks. The fact that Mark himself cares enough to dedicate this much time to the incident after the fact really says a lot of positive things about the company.
This is where I was going to go with my comment. Mark is going way beyond the call of duty with his continuing analysis. I would suspect he donated the testing guns to KB for his destructive tests. Edwin mentioned he was sending his back to Mark after his concrete testing, I’d bet Mark ate that one as well. If I had a desire for one I would not hesitate to buy and use. I’ve shot 50’s and I don’t see any practicality in it for me.
@@kinzieconrad105 ....and water under high enough psi can cut steel.... le gasp......
@Kinzie Conrad
Did you not even watch the video? They buried the barrel in 4 feet of concrete and it still didn't break the threads, you're an idiot lol
@@ISAFSoldier Not just steel, scary ceramic too!
It's also great material to educate idiots with. I have serious respect for Mr. Serbu
Sketchy ammo was to blame. I am a fan of Serbu. Keep designing and building. We need more guys making new stuff.
I am a fan of Serbu, and I agree that we need more experienced gunsmiths making new stuff.
Even Scott talked how old the ammo was and that is wasn't produced anymore and also said he did not really know how "hot" the rounds were.
I'll be working on a gun soon
The problem with surplus of unknown storage and transportation history, some could get exposed to excessive heat and/or movement, degrading the inhibitors, greatly increasing burn rate.
Sketchy ammo doesn't excuse poor safety design
I find it “funny” that even though Scott himself said the gun was not to blame people went out of their way to make assumptions and call you/your business out based on nothing but speculation.
Scott suffered a seriously traumatic injury and lost enough blood that he can't really be considered Scott anymore
@@macbook802 he ain’t a cyborg
@@manbaby9166 New Kentucky Ballistics Mascot be like
Scott-borg, a man of steel and heart who has come from the future to stop evil inflatable dinosaurs and eggplants
I think part of it is the design already sketched a lot of people out. Tbh before all this I saw the rn50 and was like fuck no, that things like a fucking factory made pipe gun, I don't trust that not to become a factory made pipe bomb in my hands. When KB happened i was like "it was only a matter of time". Ironically in the long run it took it blowing up to convince me I should get one. After having seen all the testing I'm a lot more confident in it being safe and fun to own.
@@Badspot Dude, take off your tinfoil hat.
I'm a bit flabbergasted how people thought a piece of plastic had enough tensile strength to withstand enough force for the back of the gun to blow up rather than the plastic. ON WHAT PLANET IS THAT POSSIBLE? - ok watching the rest of the video now.
Would star tracks plasteel do that
@TheGunCollective You also have to wonder how every shotgun doesn't blow up from the plastic wad that's shot through EVERY time it's fired!
@@markserbu Even worse: Shotguns with chokes. D:
Honestly, people making these comments likely didn't watch any video on the matter to the end, and have invested exactly 0 seconds into thinking about / reading into materials science.
Exactly what I thought from the very beginning! It had to be something other than the proper powder loaded in that round. Glad Mark is vocal about this and calling out the stupid “dog bark”ing people and their comments.
Most people are dumb...They don't try to understand the physics behind something and they make up what reasons they think work best instead of actually listening to engineers and other S.T.E.M. qualified people that can explain it through math and sketches.
As for the younger generation ..we've seen so much dumb shit online we can spot a troll most of the times.
From the test that Kentucky Ballistics did, someone tampered with the SLAP rounds that he bought, and loaded them way too hot. The ammo was to blame, not the rifle.
When you obtain ammo that has never been offered to the public, what is available "fell off a truck somewhere", you are taking a very big risk especially considering the price these rounds bring.
how much extra powder can a .50 BMG case hold?
@@ZE0XE0 enough to blow up a .50 cal rifle apparently
@@aethelon4144 No, it had to be the wrong powder. Even a compacted load in the .50 wouldn't cause that serious of an over pressure, it was most likely pistol powder.
@@ZE0XE0 The burning rate of the powder used is very important, faster powder as used in pistols is less dense than slower powders used in rifles, a case full of fast pistol powder could be responsible. Or something other than gun powder inside the case.
Kentucky’s blowup, from the perspective of a reloader, looks like classic overloaded round. Barrel obstructions USUALLY banana peel the barrel, not blow the back of the bolt/chamber open. Especially seeing him fire the rest of the ammo from that batch he bought, almost every last one gave clear and loud warnings of a hot load.
Whether the failure mode of the RN-50 could or should be different is another conversation, but the ammo caused the blowup. I’d bet a not inconsequential amount of money on it.
A little stupid thing that some ill educated gun nuts do is clean and shine their loaded brass in a vibrator , a big no no, you literally remove all coatings off the powder and if it's double base powder you quite literally have made a very destructive instrument, can't say the word UA-cam won't let me , video creators can but commenters cannot.
What about his blowup doll now
As seen by his other demo tests of guns, there's not really a design out there that would be much safer than the RN. The Barrett is the gold standard .50 and that thing would've still likely killed him
I could see that as well. In all of the pictures I've seen of obstructed barrels being fired into, there was ALWAYS at least a bulge starting near the obstruction point, and very often splitting. It's the thing every reloading manual has warnings about. An over-charge can cause excessive wear or binding on the action and a massive over-charge will blow out the action. The pressure spikes too high before the bullet gets out of the barrel. The fact that all but one of those SLAP rounds were over-charged to an extent is plenty of evidence that one or two could be explosively so.
When you're hammering, or otherwise using tools and force, to open the action, your rounds are too hot.
Except on a Mosin. Hammering is expected.
@@Robert-qm7yi This was my thought as well.
That pressure wants to go somewhere, and if it's going anywhere but forward, there's a good chance you're going to be on the receiving end of whatever that pressure is dumping it's kinetic buildup into.
Be it the end cap and lugs of the gun, or the remains of the receiver folding over backwards into your face. At the end of the day, you're sitting inches away from a contained explosion that's almost _four times_ the rated pressure of the rifle, at an already extreme pressure rating.
The only way i see to account for that is to over-engineer the hell out of it and hope it doesn't fail, because at those kinds of pressures, no failure mode is going to be pretty.
EDIT: Forgot how fucking insane the pressure actually was, just looked it back up because i wasn't sure.
I still can't believe Scott's alive.
Mark, I'm happy to see you addressing this stuff in its entirety. Big respect for attempting to cover all aspects of concern.
What is failsafe? You cannot prevent failure, but you can make it fail more safely. For example, if the top of the barrel was intentionally made weaker than the cap, then the rifle would blow-up upwards, instead of blowing-up in your face.
real talk with Mark Serbu. well explained from a passionate gun-maker.
The only thing that scares me about my RN50 is the thought of carrying it more than 20 feet. And firing more than 10 rounds in one sitting. Fantastic rifle and the most cost efficient method of delivering 50bmg to a target.
10 rounds in one sitting, what hurts worse. You? Or your bank account? ;)
@@bananadad9228 yea a 50 caliber is fun and all but shooting 30$ downrange in a few minutes starts to hurt when you think about it
@@jacobkudrowich The only difference between men and boys is the price of their toys. If putting 30 bucks of ammo up in smoke bothers you don’t ever own/shoot a machine gun, Gatling gun or shoot rifles chambered in most classic “dangerous game” cartridges. This is why traditionally most metallic and competitive shotgun shooters reload their own ammunition. For me and many other shooters who reload their ammunition it brings another element of enjoyment to shooting sports.
The only thing that scares me about shooting .50 BMG to begin with is the entry fee: buying the gun and a reasonable stockpile of ammunition.
@@drrocketman7794 I've got about $3100 tied up in my RN-50 plus 700 rounds -BUT- I hand loaded all my ammo.
Anyone who's taken a physics course, or a materials course... and passed, knows that the pressure required to rip the threads off even a grade 5 bolt of that size is phenomenal. Mark builds a good gun. I just got my new Serbu 50 cal and shot it the first time last weekend... not a worry in my mind. Keep up the good work, Mark.
Obviously everyone who's talking shit about the gun doesn't know anything about engineering and design. A part (can be just a beam of steel, but here the gun) has to withstand certain forces. It shall be designed in a way it's safe for normal use. For mistakes and stuff the part can usually withstand around 1.5 times the normal force. Beyond that, it's not the designer's fault.
You forgot to multiply the thread load capacity by the 2 fucking 1/4" steel backers behind it that the cap completely sheared off like they didn't exist. People are just ignorant. I don't know where the 200k psi rating Mark threw out came from but it seems a little low to me. To move a cap backwards fast enough AFTER failure to sheer off that much steel, it had to be SIGNIFICANTLY over the failure load, not just slightly. If it was slightly over it would have dented the steel and then deflected up.
US Army small arms repairer here. IIRC, it has been many years, sabot rounds arent supposed to be used with a muzzle brake OR flash hider. (yes even the conical flash hider for the M2) because the sabot separates from the round at the end of the rifling. If a muzzle device is attached it can cause the discarded sabot to ricochet off the device and strike the round, causing a deviation in the point of impact. It doesnt happen often, but often enough for the US military to advise against it. A micro deviation at or near the muzzle, can have a huge impact at 1200 meters and beyond. Small dents and dings in a flash hider have very little impact on the weapons operation. A round striking 50- 100 meters outside the impact zone, can have catastrophic results for both the Military, and any civilians or military personnel outside the impact zone. 5 of the 6 branches I know use both the M2 and the Barrett, USA, USMC, USN, USAF, and USCG. I have no information on if the USSF uses either system. The directive on this did not come from any of the branches individually, rather it was a DoD issued directive. Just my humble opinion based on the information I have been exposed to over 28 years in the US Army. I could be wrong.
m.ua-cam.com/video/3c4wtfV5_ao/v-deo.html
In this video he says it's not the slap engaging with the muzzle. He also hates my idea of chamber vents. I don't see whats wrong with the chamber vent idea.
As another US Army Small Arms Repairer (Since 1995) I agree.
thank you fellow snek
I know they didn't let our sneaky squirrels use them in the barrets. They didn't like us using them in the ma duce that much either. I could be wrong, but it's my opinion that was mostly because those rounds were getting pretty old and they didn't trust them much because of the age. I'm pretty sure we only had once can issued in our entire company, and we got it on a fluke. After the accident I tend to agree. I'm pretty sure that nobody has loaded new SLAP rounds in a very long time.
So, not a safety issue but an accuracy issue. Thanks for clarifying
Hey Mark 🙋it was clear after Scott's test video, that the ammo was significantly overcharged. If gas prices weren't so godawful high I'd put an order in for an RN50 today. Keep being awesome.
For some reason they decide to go on a witch hunt after Mark even though the ammo used during the accident was, as you said, overcharged. A normal .50 round would never be able to shear the steel threads on the rn50. (In my opinion)
@@Noname-yx8gf 100% facts👍
Interesting fact I learned afterwards is that a "undercharged" round can also blow up stuff badly. At first it don't make sense. Once you think about it tho if a round has more powder inside it, less surface area of the grains of powder are exposed to the flash over as it ignites. However if you have less powder it exposes up to like 3× more powder right away as it flashes over and it will cause a higher initial spike of pressure. A casing loaded with more powder has a longer explosion but at a slower rate. If that makes any sense lol. Then a cartridge that has a round pushed down inside it will go off like a stick of dynamite as it will go off nearly at once and have the highest spike I think. Someone who knows this stuff better can weigh in and explain it all better. Neat stuff tho. Unless you're the guy being exploded. Then it kinda cramps your style a bit lol
Just go ahead and give yourself a tracheodomy before testing weird loads made by a stranger and you'll be fine lol
i'd put in an order anyway if they were available in my country. fuck the gas prices, i'd rather walk.
@@hughgrection3052 this is common in nitromethene racing, they literally wash the cylinders with fuel, so much so that the engine is constantly teetering on Hydro lock, even at red line. If you want to hear more, let me know
Thanks' so much Mark, this was great info I didn't know. We shoot a lot of SLAP rounds on our channel but were only going off what everyone else said as far as muzzle brakes go when we first started shooting the SLAP rounds. At first, we were shooting them with the brake off, but the dang thing kicked so much Justin made an insert (basically a machined tube with a bunch of holes in it) for our Bushmaster BA50's big old honking brake and it works just fine. Thanks for the common since showing the footage of the rifle blowing up, and one no in cement. It doesn't much clearer than that.
@Going Ballistic Thanks! As pretty much everyone knows, the plastic sabot *can* damage a muzzle brake. In extreme cases, pieces can be blown off and fly backwards at bullet speed. Hell, in the prototype phase of the BFG-50A we had brakes lose some pretty big chunks, and that was just from propellant gas! Excellent idea with the perforated tube insert!
@@markserbu thanks for the response, I’ll send you a picture of our insert. I would like to get you take on it.
Chris
Can't imagine any other creator in any other industry being as open as Mark
If I was in the US I'd definitely give him some business
Same here @David Hughes!
I can see how uncomfortable saying some of this is making Mark Serbu!, and learning internet culture where Keyboard Warriors can verbally assault people who they wouldn't fecking *DARE* to mouth off face to face is a lesson that can be hard to learn!.
Fair play to Mark for his openness!... As for Failsafe, I.E. PROOF-ing *anything!* a great *Old* saying is it's hard to *FOOL* -proof *ANYTHING* because they just keep making more ingenious *FOOLS!* by the way that's not a dig at *KB* ,I think Scott is cool as feck!
Keep your head up and keep doing your thing Mark!
I want to see a knock off version of RN-50 by Hi-Point or some other low-end manufacturer from China or Ghana or Peshawar....then we can look forward to some real carnage.
In the US, "giving someone the business" has negative slang meaning.:-)
@@hueyiroquois3839 What does it mean then, besides the literal meaning?
It means giving someone a beating.
All BS aside, the RN50s rep took a beating in the court of public opinion. I could not imagine anything more infuriating than being judged on something,that the firearm was never designed for,by a bunch of people that know just enough to sound like they know what they are talking about.
Carry on Mark.
Thank you for doing all you can to educate the masses.
It has taken him like a year to get to the point
@@CAMSLAYER13 The ammo was in question from very early on, it was determined it was the slap rounds mere weeks after incident happened, it was covered by marked himself then not long after that KB destroyed another RN 50 to demonstrate the forces needed to destroy the breach cap as well as the lugs that everyone likes to get philosophical about.
Truth is nothing would have survived that,… there was a dude not long ago that loaded a tube mag shotty with questionable ammo… it chain fired the whole mag disintegrating the fire arm and indeed his own arm. Now , do we demonize that model of shot gun because of the incorrect ammo, or,as animals equipped with the powers of deduction, rather than flock mentality, do we identify and remove the greater hazards?
Mark is clearly annoyed and rightly so. Half informed critics are as useless as biased ones.
@@riz3nfpv306 He has every right to be upset but, unfortunately it's the way it is, the damage done cannot be reversed.
Sucks for him, but the gun has a bad reputation now. KB's video will always have more views than any of these video's, only very few people in contrast will see any of the breakdown videos.
@@kinzieconrad105are you saying it blew up because of the threaded breach cap? Do you think an m4a1 would have done better ? Get educated bud… or be one of the guys we can laugh at
@@Chzydawg I don’t know which are dumb and which are dumber. The ones starting the BS or the ones Taking it as the truth.
It actually is saddening, you need to remember producing an item to supply to the public is a difficult enough task. You guys are blessed to have guys like mark in your country to design and supply these products. Also the birth of the RN50 was to supply a need in the market for a budget 50 cal…he listened to that need,why tear him down?
If a guy like mark comes under scrutiny from his peers in his community, and is found free of liability, he should be supported. Not continually dragged through the mud
Ok fair ,in the name of safety - IF the gun was faulty sure get it out there - but it’s not , why keep up this fallacy or misinformation? Why not go after the guys that supplied the rounds?I don’t get it.
Been following along from the beginning. As a Mechanical Engineer (now retired) specializing in Forensic Failure Analysis for over half of my career, I find it fascinating the process you have gone through to this point! There's an old saying: "The Devil is in the details".
🤔
Regarding "fail safe". This is like when people ask locksmiths for locks/chain that will stand up to an angle grinder cutoff wheel. **Nothing** stands up to a cutoff wheel.
"Okay so we sell this hardened security chain by the foot, right?"
"Yeah..."
"How do you think we cut it to length?"
"... oh."
Totally right abrasives are the way to cut the hardest material most people have no idea how to cut what with what properly
(In Beavis' voice)Uhhhhh, cutting torch?
Or the people that want extra screws in the deadbolt I their front door......that has windows on each side.
If it's really tough it might take more of the wheel to cut it but it WILL cut it. 🤓🍻
@@mephInc Surely the criminals won't take the path of least resistance... surely...
Of course, depending on how high said criminal is, ya never really know!
Before the gun blew up, I always thought the design of the RN-50 breech screw plug was just supposed to be a cheap way to make a gun. Never considered the safety.
Then I researched the sheer strength of threads vs lugs. It’s amazing how much more secure threads are than lugs.
So, the RN-50 is probably more safe than the other 50 cal rifles.
Threads are only safer when properly machined and torqued. Threads also don't take very well to wear and repeated cycles as well as lugs do, which is why they're the most common design.
Threads were used on breech loading cannons right up until WW1 and are still used in some modern artillery.
Talishar doesn't seem to be the most informed commenter on this. He has a point about thread wear but as I said interrupted threads are used in some modern artillery to this day.
The RN-50's design has the ears to ensure the minimum amount of thread length engagement. I don't believe the RN-50 uses a tapered thread so... meh
If he really thinks the design is unsafe, I'd love for him to put his money where his mouth is and do the Reliability Analysis. Show me the weibull baby!!
i can only recommend AVE, his tests show how much force is required to overcome threads / the friction of those.
@@Talishar Obviously you haven't heard of the Vulcan V50.
You are 100% correct. I’m a retired engineer and I know that what happens at the muzzle brake can not cause the chamber to fail. The muzzle brake is the weakest part of the weapon, and by the time a projectile reaches the brake the chamber has already reached and passed its maximum pressure.
Also the fact that there was no damage to the barrel, no expansion or peeling, proved that as being wrong. The barrel is strong, but it would be an extreme oddity for a barrel of any kind to be stronger than the chamber. The nature of gun design alone makes that unlikely, and the fact that the barrel is threaded into the receiver which is providing additional support for the chamber.
It was clear to me from the first video of the explosion that it was a massive over-charge, and when things exceed the expected worst-case possibility design, it is impossible to predict the outcome.
Common sense is a flower that does not grow in everyone's garden.
It's refreshing how confident you are in your engineering and your willingness to tell people they are idiots when they are being idiots. Entirely too many people are overthinking this entire incident and looking to place blame where it doesn't belong. Keep up the great work.
There's nothing common about common sense.
I dig that… I’m gunna use it.
You had my 👍🏻 at the first sentence.
I'm glad that Mark (although jokingly) called out Edwin about his Oxygen Bottle in a Safe antics........ that was super stupid. Sarkissian should know better than that.
I had been looking at buying an RN-50 from my LGS for a while. I bought mine AFTER Scott's blew up. Why? Because of YOUR immediate and calm response AND because of what I saw in the damaged breech end. The fracturing pattern in the threads showed clear excessive pressure.
You build great guns. I love my RN-50. Thanks again for refuting the garbage others have put out about Scott's accident.
It was very clear from his response to the accident that he's the sort of guy you can trust. He was very concerned with finding out the cause and address it if there was a design flaw or manufacturing issue. The problem didn't turn out to be on his end, but it was obvious he was focused on finding out.
I would prefer a bolt-action or automatic .50, but seeing those threads hold themselves from a dozen mystery cartridges embossing their headstamp into the breech plug, that makes me confident enough to a box of proof loads with the thing without breaking a sweat.
The way Mark has handled this-- and this video in particular-- really inspires confidence. I'm an engineer and gun enthusiast and all of Mark's remarks have my engineer brain nodding in violent approval. There's no such thing as fail-proof. Just fail-resistant. For example, I can layout some hydraulic hoses with different sized ends to make it only go together one way, but a trip to the local hose shop for an adapter and just like that it's plumbed wrong.
Mark's analysis is spot on, and it shows a dogged determination to vindicate his design-- which I sure as heck would also want to do if it was MY rifle that ignorant people were accusing of being at fault.
Weak threads? Anyone ever look at hydraulic cylinders? Its all held together by fine threads that hold back all that pressure for hundreds of thousands of cycles. 100% wasn't the fault of the threads, definitely an over charged round or and war relic sabotage round with C4 in it that happened to find its way into that batch of ammo. I'd definitely recommend weighing each round of ammo looking for discrepancies when buying old ammo or from anyone really when talking about .50BMG.
Good idea hadn't thought of that.
Yeah man they are stupid as fuk
.. and the threads on the gun are thick and.coarse
Some artillery pieces use an interrupted thread to secure the breach plug. There is absolutely nothing wrong with a threaded plug or cap with adequate sized threads and proper contact. Given that Scott from KY Ballistics did another test and ran seriously overpressure rounds through an RN50 without failure, I'd say the RN50 is just fine. It took making what was effectively a little pipe bomb to break the gun.
@@RustandRedemption The engine in your car does the same thing with a spark plug. An engine at 3000RPM is spinning 50 times a second and in a 4-cycle engine, that means 25 explosions per second per cylinder that your spark plug not only contains, but ignites as well, thus placing itself at ground zero for the combustion event. Absolutely nothing wrong with threaded plugs or caps.
People tend to underestimate bolts and nuts, tension rating wise.
Usually by a factor of 5 to 10.
the people pointing out the "weaknesses" of the screw cap clearly have never seen how artillery or naval guns work... those breach blocks are literally threaded, well partially since they're typically a 90° lock which means there's LESS material thread wise in contact between the block and the barrel.
Yeah in the military we had way worse examples that didnt fail. Now I have never fired a RN50 but I would trust its screw cap, because I trusted things like chicago fittings for high pressure liquids and gasses. You hit the nail on the head with this one.
Barrel in an artillery gun will break before the lock, also 90 degree straight lug is safer than threaded ones...
@@Uryendel yea there's a bit more meat to them but you also have quite a bit of surface area with thread engagement which is what gives threaded caps their strength. i know it's not the best of comparisons but there's some similarities in function.
@@ToeCutter454 It's not just there more meat to them, they're designed to fail in a safe way. The RN-50 would be fine if they made sure that the cap was stronger than the barrel (either by having a stronger cap/locking mechanism or a weaker barrel)
@@Uryendel That's an interesting idea, but if the barrel blows up on a rifle like this it's still gonna do very similar damage to the shooter, I wouldn't call it "safer" by any means
We all know the RN-50 is safe as any other 50 BMG firearm
And at 200K PSI, a case vent would just turn into a plasma cutting torch
Be like a 40K plasma gun. Saves itself by killing the user.
@@SilverStarHeggisist a smart user throws it like a hand grenade.
@@SilverStarHeggisist Maybe the RN-50's machine spirit was upset that Scott didn't use the proper incense and anointing oils before he fired it.
@@phalanx3803 yes, and that does help eliminate hostiles. There's a minor problem, the angry binary noises coming from the local techpriest at such a ancient and revered weapon being so mistreated.
@@SilverStarHeggisist not my fault they have a habit of overloading and it still purges heretics so the Emperor is happy.
10+ years in the industry…seeing an owner respond like this is porn. Truly amazing to see you come out and set things straight with facts. I need to buy your stuff now 👍🏻
We colloquially use "failsafe" to mean cannot fail, but that's not what "failsafe" actually means. It means that when something fails, it fails in a safe way. Usually in the form of an intentional weak point. I'm not sure how a failsafe could be designed for this problem. As you point out, simple case vents aren't going to do much.
Any failsafe would be better than none (like the RN-50)
@@muwuny How about telling us which firearms are designed to fail safe?
@@muwuny Did you watch the video?
Did you listen to the words that the man said?
Did you understand what the words the man said meant, or not-even-close?
Because ^The Evidence^ here would suggest at least 2 "No"s in answer to my questions, but hey, you keep-on trying to talk to the grown-ups if it makes you feel clever Buddy... 😉👍
@@muwuny you know what the weakest point in a firearm HAS to be? An unobstructed barrel. Any other weak point and explosive pressure will find it. Maybe not on the first round, or the first 500, but eventually that "fail safe" will fail when it doesn't need to and cause issue. Pressure will follow the path of least resistance, so if that less resistance is anywhere other than pushing a projectile down a barrel, then you don't have a firearm.
@@muwuny You're dealing with pressures at 300% of the pressure rating of a .50 bmg cartridge; More than 180,000 PSI.
There's no way to make that fail safe, anything releasing that much pressure in any direction other than away from you is going to end badly, usually very.
That energy is going somewhere, and if it's gotten to the point where the equipment starts failing, it's usually everywhere.
When you're dealing with extreme equipment, safety is usually managed at the individual level, not the equipment level, for the simple reason that, under extreme circumstances, you just can't get something to fail safely.
Precautions need to be taken, safety needs to be considered at every step along the way, and both of those need to take priority over anything else.
Simple fact of the matter is that Scott got a bad reload.
A very, very bad reload.
There's no accounting for rounds that operate at near 400% of conventional cartridge pressure, that's like taking a hair dryer and hooking it up to high voltage lines.
And when failsafes aren't really an option, the only thing we can do as a community is learn to take precautions, to consider safety more.
Because in the end, Scott fucked up. He didn't _know,_ he couldn't have... But there's lessons to be learnt in every accident, and i don't think the lesson to be learnt here is one that we can simply push off to engineering, and wish them best of luck with it.
This one's one we can all learn from.
And for the record, _no rifle in existence has a 4x operating pressure failsafe, quit the vindictive bullshit._
Admittedly, I was one of those suspecting a design flaw when KB blew himself up. For me, it felt logical that when a gun fails, the mass between explosion and the user should be as big as possible and some obstructions (like enclosures) would reduce the force of shrapnel in case something goes wrong. It´s logical that the "ears" that were sheared off were the almost lethal parts that punctured scott. Thus, I found the comparison experiment with the M2 really good as it showed that this really doesn´t change things for the better, but adds other random factors to the issue.
But that´s all besides the point. The gun blew up because the ammo was tampered/faulty and any gun would have blown up. As soon as the gun blows up, it´s rolling the dice if shrapnel goes your way and where it hits you. The "ear" could have missed or it could have punctured the skull.
Well said.
Basically spend an extra 8k for a freak failure to be a bit safer…
If can avoid the problem shouldn’t need the extra safety I suppose. Cost vs benefit.
@@carsonhunt4642 reminds me of ww2 german tank overengineering, i mean the designs were good and all ¿ but did they really need to add so much complexity and extra features when it would work just fine with much less? i really like their tanks and i can easily see they made a massive amount of bad decisions. Tho those bad decisions are one of the biggest reasons why i like learning about engineering in wars
I argued the strength of the rn50 for several days after the incident... a whole bunch of people saying "I'd never buy one of these pipe bombs" and then I broke down the numbers for them & pointed out the fact that they would've never put down a deposit on a RN50 to begin with, so that just leaves more for the rest of us... 🤷♂️
Thank you for doing all you do, Mark.
@@rsh4599 that pressure max is so crazy to think about. If anything u would think that ppl would know it is a good rifle becuz it took over x3 the pressure to blow it up. I bet none of my firearms could take 3 times the pressure.
It is pretty obvious from Scott's recent video finishing the last of the ammo box that an improperly loaded round was the cause. I recently blew a 7.2 ounce muzzle brake off a gun with experimental sabot ammo. It simply sheared off the thread adapter and went downrange into the woods somewhere. Recoil was normal with no damage to the receiver and no appreciable case head expansion or case pressure signs. It actually took a few seconds to realize what the downrange noise in the woods was and that the muzzle brake was missing. We can usually tell a lot from examination of what remains. Scott's experience was clearly an over pressurein the chamber event.
I was initially in the sabot vs break camp, but I was in a gun store and had an epiphany. I was staring at a pre-WWII Reminton Auto-5 with a Cutts compensator. Shotcups are a lot like a sabot. Even if you were a royal fudd like my grandfather, who used a fiber wad and no cup for black powder skeet loads (sorry ghost of Gramp George, no, no, no, oh hell no), then you're really making it worse by shot column vs comp. We've been putting comps on shotguns for a century. If this was a problem, we wouldn't have noticed earlier. The only answer left is ammo, and bleed off holes for a 50 are going to be closer to a cutting torch than anything.
A break will never make a gun explode unless there's some reason the barrel has been completely obstructed lol, pretty sure that KB would have noticed this and whoever came up with the idea is an idiot
How can the sabot make the gun blow up? By the time the sabot gets to the muzzle the pressure already has collapsed.
@@DickCheneyXX the argument was the sabot plastic clogged up the muzzle brake. problem is if that was true the muzzle brake would blow off not explode at the chamber
@@toomanyaccounts also, serbu provided the barrel and brake, specifically for these rounds
@@iceman5117 also the claim that slap shouldn't be fired through a brake appears to be nothing but Fudd lore. the guy knows the President of Barrett so if Barrett ever said anything he would know it.
it takes a number of slaps to go through vehicle armor and hence a machine gun is far better for that then a ten round semi auto material rifle.
Scott from Kentucky Ballistics did a test with 3 rounds, the first with a normal powder charge, the second with a 1.5 times powder charge and the third with a heavy double powder charge. It was the third round with the heavy double powder charge that blew up in almost exactly the same manner as the first RN-50 that almost ended him. Scott followed up with a second test with a new RN-50 and a new round with a heavy double charge. Again the results were almost identical to the first one that blew up on him and the first test rifle. None of the rounds he used for the tests were Sabot rounds to eliminate that as a factor. His conclusion was that he used rounds which he could not verify were factory loads. His new policy now is to only buy rounds from sources that he knows and trusts.
It wasn't the gun that was faulty, it was in fact bad ammunition.
Well said. It's like putting a 400 shot of nitrous into a 4 cylinder grocery getter. Even if you can get it to not extinguish the plugs, it's not going to last very long.
this doesnt change that the RN50 has unsafe points of failure, the cap is its main weakness and any failure in the cap will result in it being tossed at the shooter as shrapnel, an easy way to fix that would be to design the chamber walls such that they were still strong, but weaker than the cap, so that any round loaded normally still fires normal, but dangerous overpressure would rupture the chamber walls, venting pressure to the sides, where, on a safe range, noone should be standing
@@gaiamission7200 if you can thing of a way to make a gun explode in a safe direction, let me know.
@@evoxis1058 it's extremely doable and common on reputable manufacturers. Also he totally just explained it but ok
@@gaiamission7200 did you miss the part where scott also blew up a barret 50 and it did exactly the same thing?
The amount of people who don't understand that a bolt action is just interrupted threading is astounding. And that complete threads are going to be stronger.
Mechanically there's a huge difference between machine threads and bolt lugs
I didnt know anything about that and i also dont have any thread knowlege. That being said, without any knowlege of that stuff, i always though a bolt action was safer compared to that breach cap just by the look of it. Its like judging a book by its cover, its ok to do it but don't go around spreading potentially miss information about the subject to anyone.
@@Pilot8091 how so?
Depends on coarseness and depth of threads. Yes artillery is interrupted thread breach but very coarse and deep. A bolt on bolt action even one with 9 lugs is not interrupted thread it is similar but not interrupted thread. And much stronger than medium to fine solid threads.
@@Pilot8091 yes, of course. They both distribute the pressure (force) across more surface area.
I'm actually convinced that the cartridge which injured Scott was *in excess* of 200000psi, because even the rigged cartridge meant to obliterate the rifle in his test couldn't do nearly the same damage.
Looking at the test rifle also championing through the rest of those SLAP cartridges before that actually inspired a lot of confidence in me of the screw plug breech, because you've got those _crazy high_ pressures with most of the cartridges seizing up the breech something fierce, extraction was a project almost every time, and still the gun didn't blow or even so much as burst or bulge the barrel.
I'll be frank and say that the RN-50 isn't a dream gun for me, but I'm also convinced it's an extremely safe rifle, few other guns on the market would tolerate the nonsense conditions it could go through here. I mean, will people call an antique Colt 1873 a death trap because you can Elmer Keith the thing with smokeless handloads? I wouldn't, and those guns aren't even drop-safe.
I think in many ways it's an awkward rifle, if money wasn't an issue I think it would be an odd choice, but agree that it appears to be very rugged/overbuilt
My guess would have been pistol powder or something, if not purposely made to be over-pressure
@@Wehra96 There's a lot of different things which could have been wrong with it. The powder could have degraded from bad storage conditions _(and according to some, these SLAP cartridges used a different powder from normal .50BMG ball which was less shelf stable, however true that claim is),_ along with it potentially being a counterfeit made with something like pistol powder, which itself could have degraded.
Some suggest that it was a salted round, like Project Eldest Son, but I find that be less likely. Being a Cold War spy project thing, and such a specific one at that, it seems to me that it would be odd for it to pertain to a .50 BMG SLAP of all things, something which never got around anywhere with any enemies of the US or NATO, and then that cartridge would have to make its way back and onto the US.
I really think that it's either a counterfeit which wasn't expected to be shot, or that it was a genuine SLAP but which had its powder charge degrade one way or another, the odds are just far higher.
Why doesn't it use interrupted threads? That would have been way more convenient
@@tedarcher9120 using ears as safety check to ensure breach is closed would not work if you had essentially a quick change interrupted thread breach cap. Or you’d need to much more tightly tolerance the space between rear of cap and ears, which could interfere with the closing of the gun. A workaround I could see is an indexing detent on the cap that would only allow the gun to fire if the cap is rotated to the proper location, but then we are talking a more complex safety mechanism than just making it so the action won’t close until you have adequate closure of the breech cap.
I still feel that the rounds that were used were overloaded and dangerous. Too many people love to use heresy and innuendo without actual proof or facts, especially on the internet. You know what you're doing Mark and you stepped up from the beginning. I'd buy one o your 50's................ If I had the money, lol. Seriously, thanks for all of the videos you've put out and for addressing everything. Stay safe.
Mark, you've earned my respect just from the work you've been doing on this. If I weren't a poor, I'd have no problem buying one of your products.
It's funny Mark mentioned being less safe by trying to be more safe. The 1st Generation Dodge Viper is kind of an example of that. Back in the late 80s, there was no traction control system or stability control system. The driver's right foot was the traction control system. The driver's hands on the wheel was the stability control. The 1st Gen Viper had very wide tires for the day (and they're still wide today) in order to give it lots of grip for that monster of a motor it was carrying. And it worked! The Viper had a ton of grip, but it was also kind of a problem. You see, you could use all that power and get going really fast indeed, but it also meant that once you crossed the limits of traction, you were going really freaking fast when it did let go and chances are that most drivers didn't have the skill to bring the car back in line. Issac Newton was in the drivers seat at that point and you hoped that Chrysler's engineers built a safe car, because you f***ed around and were about to find out.
The viper is still one of my favorite cars ever. And great analogy. Those big tires are so sexy though 😍
having spent several years driving an early viper I can tell ya that when you finally exceeded the grip / handling limits - there was lots of flailing arms, swearing and sweating and the eventual change of underwear and stiff drink hahaha , that car forced you to concentrate 110% of the time when driving it, even if just popping to the shops...
But it was such fun and a very rewarding car to drive, even if my ears didn't agree with my choice of straight thru side exit pipes >_
That car had no safety features 😂😂
@@6FStyleCo seat belts and good luck.
i dont know if i couldve thought of a worse metaphor. the first gen dodge viper was a death trap
One thing that I've wondered since then: if the threads had held for that round, what was the next failure point?
Imagine if it was fragments of the firing pin assembly, heading straight back through the shooter's torso?
The way the guns assembled wouldn't the firing pin have to come out through the back of the cap, though?
@@mustangmckraken1150
Yes. Cap stays and pin blows right through it.
Imagine if that cap had as many threads on it as a modern inline muzzle loader...
@@wilsonrawlin8547 It's also possible that, with enough pressure, he could have simply split the barrel back by the action. Which would have had a nearly identical effect.
@@PhotonHerald
Indeed. Just a massively overcharged round/explosion.
Absolutely right. There’s no way in hell the sabot would get stuck enough to blow up the gun under normal pressure. People who believe that are probably thinking about guns in movies, or those old-time shotgun barrels made from fused sheet metal. Modern, proper firearms made from quality materials are really brutally hard to create a barrel obstruction severe enough to blow up the gun with. Threading the inside of the barrel and screwing in a 2-inch bolt can do it, but less than that is unlikely to make any difference.
I’d shoot the RN-50, no qualms. As long as the ammunition is verified as standard-issue and within tolerance of the weapon.
It’s definitely written in military manuals and other manufacturers 50cal. Manuals for a reason. They usually don’t just scribble in “beliefs” in those things.
@@brianjames8600 Be specific. Exactly what do they write; “Don’t use sabot rounds with a muzzle break” or “Using sabot rounds with a muzzle break can obstruct the barrel enough to blow up the whole gun”? Because there’s a difference in intent and breadth of consequences. Do you have these manuals and instructions handy to quote them word for word? If you can, please do, as it would be interesting to see the way they formulate it.
Thank you Mark! Thank you for all you do for the community.
I own a Mark Serbu designed 50A rifle, I’ve had many conversations with Mark and his staff, smart people, great accuracy and I shoot my own reloads. 3 rounds touching at 300 yards. Hang in there Mark, this to shall pass.
@Scott McBride Thanks! One of the funniest things I read on the internet some time back was that Valerie Serbu designed the BFG-50A!
@@markserbu It’s crazy what you can find on the Internet.
As non-native English language user:
I always thought that "safe" and "failsafe" are 2 quite distinctively different words. "Safe" doesn't fail, "failsafe" fails but in the most safe way possible.
Maybe I am wrong, maybe I'm making a mistake of translating English term back into my language and then searching for its meaning.
Something being "failsafe" means it's highly unlikely to fail
But HAVING A FAILSAFE means having some sort of backup for when it does fail.
I fully understand how this is confusing
Yeah, a failsafe device or feature is designed such that a failure results in what is most likely to be the safest state available considering the failure.
So, for instance, at least one set of brakes on large commercial trucks and on railroad trains are designed to apply if air pressure is lost, rather than being unable to apply the brakes. Obviously, there will be situations where this isn't ideal(a single drum losing its air supply and overheating and starting a fire, for instance), but it is almost always better than the alternative of all the weight rolling freely.
Another example is a lot of nuclear reactors will drop their control rods in place in the event of a power failure or if the control system detects issues with the coolant system, thereby slowing the reaction to a crawl and greatly reducing the risk of a meltdown. While there are probably a few situations where this would be less than ideal, I'm struggling to think of any atm.
@@1stCallipostle The OPs interpretation is correct - something that is *designed* to "fail-safe" is precisely that; WHEN it fails (failure is always an option), it *should* fail in a safe way.
But reality doesn't always agree with your design.
Something that is safe cannot cause harm; if it can, then it's not safe, *but* we do often use "safe" to mean "very low risk". (E.g. "safe driver" - driving is inherently dangerous.)
@@spudgamer6049 and that's more or less what the ears are for on the RN-50. He designed it to take like 150 percent of rated pressure and the amount of force to SHEAR those off is incredible. The powder obviously burned far too quickly so he had a small explosive in the chamber.... ouch.,
@@ExarchGaming I disagree. When/if the design fails, it fails in a fairly bad way. It just is designed not to fail except under extreme circumstances. That's different than being designed to fail in a safe-ish way.
Not saying there's anything necessarily wrong with the design. You can only realistically design for what is within the reasonable realm after all, and I'm not sure that there are any particularly good ways to make a 50bmg chambered gun fail in a relatively safe manner that doesn't compromise it in other ways. Maybe those ears could be made strong enough such that something else would give before them, but I'm not sure how heavy that would make the gun, or even if that is realistically possible.
I have faith in your engineering. That's why I ordered one and I'm willing to wait the 18 month lead time. Keep up the great work!
The whole "sabot plastic is getting stuck in the muzzle break" thing is easy to disprove.
Just remove the muzzle break and try the same thing again.
With the same load, the gun should blow up "just fine" without the muzzle break.
Pack the barrel as tight as you possibly can with discarded sabots and fire the weapon. I would fire it from the hip I am so sure nothing would happen. Teh problem was bad ammo. probably leftovers from project eldest son.
Brake.
@@skepticalbadger You're right. English isn't my first language, as I am Swedish.
Forgive my misspelling.
Do you know why I can't get out of IKEA it's been 5 years
The most succinct, informative, and in my mind definitive review of this KB was done back when it happened on a channel called Backyard Ballistics. Despite the name, the guy is an educated professional firearms examiner tasked with gun crimes & failures. Right off the bat he said that just the threads being sheared showed it was the ammo and not the gun design. He explained several other aspects, like how a failed case will greatly increase bolt thrust, hence his recommendation for gas vents, why low-cycle fatigue is ruled out, and a lot more. Highly recommend anyone interested - you too, Mr. Serbu - check his two vids on the subject.
Just throwing this out there for some food for thought Mark and curious watchers. When I was in combat in Iraq we got tasked to actually implement spiked ammo into the battlefield ( enemy ammo calibers of course). It's a highly effective way to have passive attacks on the enemy, break up enemy moral, break up enemy supply trust, etc... As far as I know our RIFLE ammo never was spiked enough to kill but meant to destroy the weapon first, and have slight secondary injuries just as a bonus. Most times just a destroyed AK, RPK and some scratches and cuts on the hands and face/ eyes. We did have lethal stuff too but that was for mortar and artillery shells that got used for making IED's. Those weapons were tracked and could be detonated on command (very interesting tactics can be implemented with these babies). When you start talking bigger caliber rifles and machine guns like DShK's and NATO .50's there really is no safe way to destroy those weapons without making them highly likely to kill the user. It just is what it is...Make no mistakes about it though, the enemy was doing the same thing to our ammo. Hardly ever happened to americans because we hardly used battlefield pick up weapons and ammo. It's very easy to use this tactic on guerilla elements because they use what they can get most times... Saying that, there is alot of people that re sell weapons and ammo from conflict zones where these tactics are being used. Unless you are apart of the team that spiked or left the ammo on the battlefield theres not a great way to inspect and know which ammo is spiked and which is normal ammo... I would recommend never buying boutique ammo off of sites like Ebay.
I call BS on your whole story. This is the first time I've heard of the US doing this since Vietnam. And who in their right mind thinks you can buy ammo from eBay?
@@njw1977 lol whatever you say buddy. Not here to convince you of anything. Quit being lazy
@@njw1977 Let me know what local gunshop is carrying legit .50 SLAP rounds when you get a chance.
You're stupid if you think you can buy ammo on eBay.
I'm glad this "rebuttal" has FINALLY come out.
Thank you Mark for putting it in perspective and leveling the field of commentary.
I laud you for your intestinal fortitude and telling the facts regardless of "popularity".
Who was speaking bad about the gun ?
Yess we been waiting for this, thanks dude ❤️
Oh you are welcome sir!
Scott himself said that it wasn't the fault of the gun. The really hot, overcharged ammo (presumably tampered) was absolutely at fault. Threads like that do not fail unless you seriously overpressurize the chamber.
He just got super unlucky.
Anyone claiming that something got stuck in the muzzle brake is wrong and clearly hasn't watched Scott's follow up video when he re-tried the test. He went through all 12 SLAP rounds and it didn't blow up. It took a round that he specifically massively overcharged before it actually blew up the gun.
counterfeit rounds are known to exist. it takes five bucks of material to make a counterfeit slap that would go for a 100 bucks at a gun show
Scott should have blamed himself more
@@toomanyaccounts correct, they're all kinds of counterfeit slap rounds and the way to identify them is they do not have a crimp, their primers are usually brass colored and not nickel colored like real ones, fake ones usually do not have the primer sealant present like the real ones do, and on the Sabot, fake ones do not have the little cuts on the top to aid in splitting apart to release the projectile.
As a machinist and someone who has worked on all types of metals for all sorts of things, I know for a fact that cap is no joke. I also know whatever can blow it off is no joke too lol.. Lot of guys here and on KB's comments who obviously have never worked on any metal in their life trying to act like they know everything about threads, metallurgy, pressure loads.. I'd ignore it. Like you said, too many people here just want to be heard and want to pretend they're better than someone else for personal brownie points
For the most part the cip proofing actually helps you as the manufacturer. Since every gun has to be proofed, if it blows up in consumers hands you're not really legally responsible at all. As the manufacturer you can say "it passed cip proofing, so whatever made it blow up wasn't there when it left my factory. If a gun blows up during the proofing, they'll basically just send it back and tell you to check if it's an issue qith just that example, the batch or the product in general.
I appreciate the on going breakdowns and addressing the accident. I respect the time and effort that you put into this.
2,000 rounds through my BFG50 and I couldn’t be happier with the platform. Mines in .510 DTC so the ammo is all handmade by myself and therefor far from perfect which should expose any weapon short coming quicker than more consistent ammo production processes.
Thanks for what you do for our community Mark!
Why did you decide to go with the 510 dtc?
Mark your a good man for deep diving into Scott's accident! IMO I believe almost everyone believes that the round it's self was incompetently and egregiously overcharged with powder I believe that you provide a phenomenal product and that the accident had nothing to do with said product but you are good man for your diligence sir!
I think Scott proved that pretty conclusively when he (the madman!) fired the rest of those rounds in a much later video. Those were definitely spiked rounds.
Hr proved it by using the rest of his rounds and it only blew, when he put in a hot round.
Bmw had a fail safe that made frontal collisions basically impossible, but my wife still crashed it
Women do the damnedest of things sometimes.....
There's a Navy expression "sailor-proof," generally followed by the conclusion that nothing is. A sailor can always find a way to break it.
@@reliantncc1864 What's the saying about Marines? Put them in a room that has no doors or windows with a steel sphere for 24 hours and they will have broken the sphere, lost it, or impregnated it? Something like that. (Not hating on Marines, just a joke.) Doesn't matter how "safe" something is made, some idiot will find a way to unsafe it.
I just want to say that seeing the way you reacted to this freak accident & the amount of time dedicated to figuring it out has made me want a Serbu more than ever! RN-50 will likely be the first 50 I get. Products fail at some point, it's impossible to realistically prevent. How the designers of those products react to the failures speaks FAR louder than any durability test in my book
I have always doubted the "plastic sabot stuck in the muzzle brake" theory... Plastic just simply cannot hold that kind of pressure without giving way.. I have seen copper bullets of the entirely wrong caliber get swaged through a rifle bore without any damage to the receiver or bolt... I still think those s.l.a.p. rounds were loaded with too fast of a rifle powder.. Or a pistol powder... Pistol powder in a rifle will cause big problems!! But that's just my thoughts on that situation...
Love ya Mark! Keep em coming!☺👍🇺🇸
Pistol powder in a rifle is great for cast bullets. But it's also way too easy to overcharge a case with the tiny amounts of powder that are used, so you have to really be paying attention while you're loading. It's possible the same kind of thing happened here - they used a regular rifle powder when a slow-burning magnum rifle powder was needed, and ended up doing a double or triple charge.
Yep! Same here.
The genius physicist/ metallurgist/engineer ,Matt at CRS firearms , jumped on the "unsafe" design band wagon and even showed in his "expert" what you should have done.
I unfollowed him after those comments . Was very happy to hear he issued an apology and conceded that he was incorrect.
@@cberge8 The rarest trait on the internet is saying I was wrong, I'm sorry.
@@SilverStarHeggisist Almost unheard of, especially online.
Never listen to boys in a rainbow hat with a spinner on top. Or sideways baseball cap. Same thing.
@@cberge8
I also unfollowed that douche nozzle because I can't stand people who know absolutely nothing about a particular subject , except for a Google search ,then give"expert" advice on that subject. It would be like giving a brain surgeon tips , because you watched a film in biology class about the brain.
Matt's apology was a hollow gesture and CYA. He used his platform to trash a Guy and his product , that he knew ABSOLUTELY NOTHING,about
then say ,oops my bad ,sorry.
Those stating that the muzzle brake was involved should contemplate what happens if you plug the muzzle with mud - or even better: You could demonstrate what happens by welding in a steel plug in at the muzzle; then firing a shot. Measurements for the barrel diameter at the breech, before and after "dynamic clearing of the muzzle obstruction" should count for something.
Demo ranch did this already with handguns. Even threaded the inside of the barrel to fit a bolt
The concrete Sarkissian obstruction probably already shows the principle. Without the before/after measurements to prove zero extra stress at the breech.
@@SilverStarHeggisist Yes. Now do that with a .50 to silence sceptics.
@@rickoshea8138 if I had the money required, I wouldn't care what people thought lol
@@SilverStarHeggisist Serbu has a reputation to protect.
Mark, Indeed it was bad what happened to Scott. Love both of your channels. When I watched Scott's video of the Rn-50 blowing up on him. Not once did I say the gun was at fault.
Myself, I am not an engineer, Yet I am a mechanic that hunts and reloads. Lot of experience with things that goes boom and blowing up stuff also. The very first thing I thought of was, That round was over charged by or with the wrong powder. Or it being old, the chemical change with time made the powder a lot more volatile than normal. Also, for the record, I do have a place set aside in my gun safe for an RN- 50. Just do not have the land yet to fire one.
I'm glad you are talking about this Mark, I've loved your weapons from afar as a poor Canadian. I have nothing but trust in your commercialized designs and wish I could buy them. One day, I'll own your BFG, and your RN50, but again, thank you for talking about how your RN50 works and what went wrong. Especially for giving Scott another one to blow up.
Hi Mark, it's very obvious this matter has been troubling you greatly(understatement). I have know dought and believe totally every word you say about your chosen profession ie gunmaking,, I would purchase an rn from you everyday but sadly we don't enjoy the same freedoms you all do and we aren't allowed in the uk. Good luck to you sir and great vid! Be safe. 👌👍👏
There are some UK shooters who use .50 BMG long range target rifles. UK law does not ban them outright but expects users to apply for an FAC and show a good reason (eg target shooting) for owning one.
It’s so cool how much responsibility he takes over this even though it wasn’t really his fault. He wants to make sure this never happens again. To anyone.
Mark,you are spot on. I am an army vet,and ive been diggin n talkin to chums and no warnings exist that we can find. Keep on keepin on! Merica!!
Mark Serbu is basically living my dream; I'd love to start a gun manufacturing company.
I respect the hell out of a man that can put controversy aside to address a problem like this one.
The KB incident was a clear case of faulty ammunition and not a design failure of the rifle.
It could be interesting to design a new rifle that could stand the pressure of one of these rounds going off.
"Fail-safe" does _not_ mean "cannot fail" -- it means that _when_ it fails, the failure mode will be SAFE (rather than dangerous). One well-known example is the "crowbar circuit" which creates a short circuit to force a fuse to blow in order to prevent catastrophic damage to the power supply when a failure occurs.
I don’t think he meant that it means “cannot fail” but rather that for extreme cases there’s no way to guarantee it fail safely.
some people seem to use fail-safe without considering its meaning, they may mean the chance of a failure or unsafe condition is exceedingly unlikely
another good example, glider training operations. the braided kevlar tow rope always had two weak links made of poly rope, if a strong thermal comes, truck is too fast or the pilot is climbing too much, or somehow the glider cant pop its release. weak link pops and prevents airframe, tow vehicle, or expensive haul rope damage, and just becomes a small pain in the ass for the pilot to modify his flight, and for me chasing the rope through the swamp.
When there is too much pressure, it is simply impossible. Everything can become a pipe bomb if enough pressure is accumulated fast enough.
Exactly!
To Mark: As an engineers we want REDUNDANCY in safety measures, that is what "fail safe" means. Measures that are destructively tested to prove they work as fail safes (aka redundancies). Personally you should probably listen to "gun jesus". He just might have some knowledge you lack.
Screw caps are barely considered adequate on sub-guns, much less 50 cal bolt-action rifles.
And the whole "heat treat it, yeah..." comment.... for F's sake hire a materials engineer and/or metallurgist if you make a 50 cal Bolt action. Don't tell us "heat treat it yeah..."
And larger, more-secure "bigger things" (i.e. safety mechanisms) "flying off" would "fly off" exponentially slower... and would not "cut your head off". No ones "trolling" this man, but he sure loves to blame the internet when his gun blows up.
@Hornet135
Of course it can never be 100% safe. But it will significantly improve safety by a magnitude. Look at crash tests on cars. Imagine if they gave up in 1930 and just said "fuck it, car crashes occur with too many variable let's just give up on making cars safer."
Instead they made fail-safes called crumple zones, which Ian says is similar to the arisaka vent holes and safety cap which are made to redirect energy away from the user. With enough energy of course these safeties will still hurt the user. But now you need a hell of a lot more energy to hurt them.
I will reiterate:
My opinion, as an experienced, trained engineer that also shoots... Is that Mark's design is solid.
Accidents happen, and I believe the ammunition caused this one. I don't see where suing Serbu is beneficial to our hobby.
I think that the gun may have been i micro bit weaker than the new one since he shot it before but it would be neglible. So all the fault was on the slap rounds.
Sry for bad english im a swede.
It’s obvious it’s the ammo but the gun design fails catastrophically for the user. No other 50 on the market would fail so dangerously given that same round
@@OrloTheM3D1C 0:20 wrong. That could definitely kill someone.
@@OrloTheM3D1C yea but you cant fix that cause its breach.
From my engineering armchair: you don’t need to make it stronger you need to make it weaker. You want the RN50 to fail in a way that would send shrapnel down range. Add flutes to the receiver to make it weaker then the bolt cap - that would be failing safe. What you described as fail safe was a design that would never fail.
Keep up the good work
Ps I don’t believe this was RN50’s design is at fault but every design can be improved.
At 190 KPSI, there is no "failing safe".
It's simply "How much fragmentation do you want in your grenade?"
awful idea. That sounds like a great way to turn an action into a hand grenade because you're purposely giving it weak points to break apart at. The gun as built can handle proof rounds all day so it's plenty safe for the designed operating parameters plus a safety factor. Buy trustworthy ammo or load your own if you know what the hell you're doing.
Exactly. Fail safe means that when it fails, it fails in a safe way. It does not mean that it never fails. IMO, the problem with the RN50 is not the threaded breach plug, but the two support lugs behind the breach cap. In both explosions on KB's videos, the support lugs became lethal fragmentation.
@@mckennaConfig The lugs probably slowed the cap down enough so it didn't just go through his skull. If I remember correctly, it hit the lugs then went up and hit his safety glasses, which also probably spread out some of the impact, and it still broke his eye socket in a "glancing" blow. Being hit by it straight on would more than likely killed him.
@@argonzeit correct.
While the RN50 isn’t for me, I absolutely love the fact that there is a 50 out there for people who couldn’t otherwise afford one. I personally wouldn’t blame the gun for a freak accident. Especially when the guy who got injured by the gun proved it by recreating the accident and still uses the gun to this day.
Yes, but notice how religious he is now about hiding behind the truck when he's testing sketchy things. :D
He does hide behind the truck more now for sure. Lol! He still shoots the RN50 from his shoulder though. Granted he cuts in the atom bomb explosion every time now.
@@chrismaverick9828 He learned safety! Now I only some other associated UA-camrs would do so...
@@kyleheins *cough Brandon cough*.
The only thing I can think of with the army not wanting to use a brake with sabots would be from the experience gained with the 76mm or 17 pounder from WWII, where the brake interference on the proper release of the sabot severely impacted the accuracy of the weapon. Plenty of notes on that throughout the internet. It should be an accuracy thing, not a safety thing, not sure why people immediately hear of the military saying something is bad and always equating it to “Oh, so that means we all die”.
Anyways, great video, sorry you have to deal with a bunch of idiots talking shit about your products. Fuck those people.
The 17 pounder was inaccurate due to the Sabot being a new concept for the British army at the time, and it was fixed after a while. Crazy speeds (for the era) coupled with "detaching" part of the round itself...
Btw, 16 pounders haven't been used since the early 20th century.
@@nikola12nis
Mistyped on the gun size, but the idea is there.
However, even the Tank Museum at Bovington has commented on the muzzle brake impeding the accuracy of the round. We also see that the 90mm guns from later on have similar issues and why modern tanks and guns that use sabot ammunition don’t use brakes.
It could also simply be the difference between how the M82 and M2 feed.
@@immikeurnot I can see your point, but the M2 is a lot rougher on rounds, if anything it would be far more prone to failure than the M82.
In their defense.. when the military screws up.. they tend to hide it and thousands of people do get hurt. Think the VA. But it's not from target shooting. 🤣
Occam's Razor: The overloaded round was the most obvious choice. The goal of smokeless powder design is to have the burn continue for the length of the barrel so you get acceleration the whole time. The psi lowers as the round moves further down the tube (somewhat depending on grain burn rate). Barrel taper and design of the reinforced base of the round lead back to that initial max pressure being found before the round even leaves the crimp. To me that shows why the barrel exploded back and not somewhere near the brake.
That's not how gun powder works. The burn is done when the pressure starts dropping off almost immediately after the bullet starts moving.
@@randomidiot8142 black powder that is true. Smokeless powder keeps the burn going longer. That is why rifle powders and pistol powders are different. You want the heat and expansion to continue. That is why modern guns shoot so much faster and why for some calibers longer barrels don’t help velocity after a certain length.
@@randomidiot8142 No, smokeless powder continues to burn while the bullet moves down the barrel. Depending on the ammo and barrel length, you may not get complete burn of powder. This is why people argue about what barrel length is best for certain calibers. It's also why you lose velocity when you shorten barrel length, bullet is in the barrel for less time meaning you get less powder burn. It goes the other way too, if your barrel is too long you'll lose velocity, because you'll get 100% powder burn, but the bullet still has more barrel to travel and that just creates more drag on the bullet and you lose velocity. You mostly see that in .22lr because the cases have so little powder in them but it still happens.
@@randomidiot8142 You're living up to your name. please don't get into the reloading hobby
"people just want to make comments to be seen and heard"
he hit the nail on the head with that one
The idea that a screw connection is "weak" is laughable. Threaded connections are some of the strongest non permanent mechanical connections it is possible to have. Threaded connections can apply and hold LUDICROUS forces. The same person that suggested a threaded connection is weak, was probably on the same level of intellect as the person who asked "is there a way to make it so that NOTHING could blow it up?". The answer is, of course not. Why? Because the list of shit that you would have to make the weapon proof against is huge🤦♂️ and contains some of the most potently destructive chemical explosives, like RDX, C4, Det cord, and THERMITE! I don't care how thick your barrel walls are, how chunky your receiver is, or how dense your chamber is, if someone sets off a chunk of thermite in it, it'll fucking melt. If they light off some detcord, or set off an RDX or C4 charge in there, something is going to go pinging off in an unhelpful and dangerous direction. The only way to make any firearm safe is to establish upper working limits for chamber pressure and ensure the tolerance of the part exceeds all the most likely loadings in the caliber involved, while designing the object to fail in a manner that is least likely to result in injury. No one expects or ought to design around loadings that are inadvisable to begin with, like putting grenade like overpressured rounds, into a weapon system that was not designed to handle that pressure. The issue was with the round being spicier than taco Tuesdays farts, not with the gun being too weak. I'm not even a gun guy, and I know this. 🤦♂️
I read it, I agree that some stuff the gun will never be able to handle.
Yeah the threads usually don't fail before the bolt snaps.
Odd that you would jokingly belittle Royal Nonsuch at the beginning for “shitty welds” (1:00) while the firearm being reviewed is a RN-50.
I do appreciate your channel Mark very much. You are a patriot.
The same test with overloaded rounds on a Barrett 50 would prove the RN-50 design safe in my mind. If a military proven 50 also blew up. Not a cheap test though.
Kentucky ballistics already detonated a barrett .50 with a overloaded round, using the same test load he used to detonate a second RN 50 (which had the exact same results as his accident gun).
Spoiler; it was destroyed beyond repair.
@@burnyburnoutze2nd
I will look for that video. That does settle the argument in my mind.
Thanks.
@@larryclark9380 No need to look. Here it is: ua-cam.com/video/xRufSjBtJNE/v-deo.html
He's done a whole series of blowing guns up for science since the accident. It's really worth it to watch all of them.
If people lost faith in the RN-50, you'd see a ton for cheap on gunbroker.
The fact that you DON'T means the owners out there still have complete faith in the weapon they've been using. And aside from Mark, the next best source of experience with the RN-50 would obviously be it's owners and users.
I honestly didn't know this was still a thing until I saw this video. It seems like everyone figured out out was bad ammo way back then and moved on.
You fail to notice that the existing gun owners are not the only place where you can measure the effects of it. There is also the market for the people who don't own the gun yet, who might have considered but now backed away from purchasing one. That is something you don't see unless you got your hands on the marketing and sales data. To my knowledge, Mark Serbu hasn't disclosed the data but the way he's talking about it might suggest that his sales have gone down due to the speculation on the gun's safety.
@@anteshell then there are people and lots like me who want one even more now. The fact if took that much to hand grenade the action has me even more confident in its abilities.
@@larrypostma2866 that is certainly possible too. I tried not to make any assumptive statements. Rather just speculating about plausible consequences of this ordeal.
Well, Demo Ranch got a deep laugh, followed by a nasty silence when he painted his RN50 Gold and gave it away...
The only thing I could think of for making the firearm more "fail-safe" is some sort of shroud over the lugs as a buffer between the shooter and the lugs in the event of a failure, obviously you'd have to figure out how to cock the hammer with it in the way (have it flip down and latch perhaps) but something as a buffer should drastically reduce the energy imparted into the user
of course modifying the firearm could go one of two ways in the publics opinion, it could be seen as an admission that the design wasn't robust enough to begin with or it could be seen as a good faith effort to make an already well built firearm even safer, I think the result would just depend on someone's current viewpoint so not much would change
It's just amazing to me how people can say "Oh the gun was definitely at fault" when as long as I've been in the online gun community, the RN50 has been around and this has NEVER happened before to a single person. Meanwhile, overcharged .50 rounds, especially of the more exotic varieties are an almost common occurrence
Fail safe doesn't have to mean 18.1" battleship barrel. It could mean a deliberately weakened section that will fail first and direct the explosion off in a safe(r) direction. See the blow out panels on the M1 Abrams main gun magazine. Unsure how you'd design that into a firearm like the RN-50 without massive compromises.
While i agree with most of your points, I interpret 'fail safe' very diff - to my understanding it's not about the 'MARGIN of safety' or 'WHEN will it fail', rather 'HOW will it fail'
In other words, sure it has more than enough safety margin under most use X5, but what will happen when unexpected/edge case (e.g. bad load) use causes a fail? example would be casing/difflectors that would direct most (and especially bulk/heavier) shrapnel away from the user crucial mass (which would be the direct cone behind the gun).
This design principle can be seen very far back in firearms design imho.
I agree. Scott made a video where he blows up Barret 50. Wasn't as catastrophic as RN50 imo.
@@franklinAll8735 agreed. and the more i think about it, the more this vid feels like a strawman, as even wiki definition clarifies it as "in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people."
Moreover, using the footage from Scott/Edwin, brings to question was the RN50 ever tested to simulate overstressing events? or just proofing it against max stresses?
simulating failure should be part of any risk bearing design and manufacturing imho.
Edit: I think a better answer would be 'define your risk appetite, but this is the only way of producing a Reasonably Safe device, in a Reasonable Cost' - completely acceptable reasoning to me.
I've read of armies tampering with ammo supplies by adding high explosives to enemy's ammo so they intentionally destroy rifles.
but I think you're done all you can for your product. it's nice to see you standing behind your product.
There was a well documented (once secret) US program that mixed sabotage [sic] rounds into crates of ammo going into North Vietnam, for one.
Yes vietnam era for example, the US had "Project Eldest Son"
1 cartridge of the case was filled with high explosives instead of powder.
that has never been done to nato rounds. it was always done to commie block ammo. counterfeit slap rounds are known to exist. it isn't some foreign intel agency its bubba doing the feits to make money
The only difference I can see in regards to “blowing up” a gun is how the energy is dissipated.. In the case of the RN…once failure is achieved, essentially some of the parts become projectiles directed at the shooter…. In the case of the Barrett, the top frame helps “shield” the shooter from fragments…though you would likely still sustain a gnarly slap to the face…. Think blast shield on a revolver…though the cylinder may explode…the energy is directed away from the shooter…. I believe this might be the purpose of the “vent hole” in some designs..it causes a failure point to direct the blast..in an attempt to prevent the bolt from sheering and being directed into the shooter….
This. I wish he'd addressed that. Just because you can't make something fully fail-safe doesn't mean that some designs aren't more failsafe than others.
+1
When the incident took place I immediately thought of some of the secret squirrel shit we do to enemy forces in the wars we've been in. We purposely place overcharged, and booby trapped rounds in enemy inventories. We don't necessarily know who's going to use that ammo, just that it will kill them and lower moral. Any round that was overcharged like the one that got Scott, was purposely built.
This guy 🤣🤣🤣🤣
Mark, how many of your critics have designed, engineered, and built a "safer" practical firearm? Yeah, exactly! Please keep building your excellent products. I'm ony one of your countless fans.
I think there is a misunderstanding concerning "fail-safe" systems. Tom Scott actually did a video on that called "Fail-Safe vs. Fail-Deadly". "Fail-safe" is not "safe from failing". It is "Safe even when it fails". So, with early bolt-action firearms there have been fail-safe mechanisms such as a step to redirect powder gas away from the eye if the cartridge blows out to the back. In case of the chamber failing, a fail-safe would probably be something like a chamber wall that is weaker than the threads, so the wall blows before the cap, or a sturdy catch that prevents the cap from flying backwards even if it shears off.
Yes, exactly. Look at the M1 Abrams. Those engineers rightly realized that they could not prevent an explosion inside of the tank. However, they did mitigate the worst effects of this failure mode by designing a blow-out compartment for the ammunition.
Weakening the chamber wall of a 50bmg? No thanks.
Just build it well and use good ammo.
@@dbz5808 no, obviously you make it rated strong enough. You make one point relatively weaker that faces away from the shooter so if you did use dodgy ammo that part ruptures rather than possibly blowing out towards to user. Essentially you make the thing fail in a safer way in extreme circumstances.
@@dbz5808 id rather the chamber walls be weaker than the fucking breach, my guy
@@CAMSLAYER13 Sorry, at the pressures we're talking about, and DELIBERATELY introducing a weak point will simply ALWAYS cause the gun to fail at that weak point.
At the pressures we're talking about. It's simply asking "How many pieces of shrapnel do you want on your frag grenade"?
All good, Mr. Serbu! Most who will buy your firearms know what’s correct. Keep up the good work and ignore the trolls 👊
The only difference between the RN-50 and the Barrett is that when tested to catastrophic failure, the Barrett did so in a way that *didn’t* blow large chunks of shrapnel directly rearward at the user’s head. And I believe the fundamental design of the RN-50 won’t allow that to be mitigated in a meaningful way. It’s just the nature of the design. For the same reason that automatic/semiautomatic designs almost always fail more safely than bolt actions. There’s a moveable bolt with a spring behind it with several inches of travel before it bottoms out, all the dead space in the receiver to contain the blast of a blown up chamber, and a giant hole in the bottom (the magazine well) for gas and shrapnel to exit the gun. We’ve known this for well over 100 years. So why do we still use bolt actions? Because the situation in which they fail is so extreme that it almost never happens, and when it does, you can almost be guaranteed that it was due to extreme negligence by the user. The RN-50 is a safe gun as long as you don’t shoot boobytrapped ammunition in it.
I dont care what it is, u dont want 200k psi going off in any way a few inches from ur head. That barrett isnt rated to those pressures either, and at those pressure every part just makes a bigger grenade.
With the pressures we're talking about here, a semi bolt wouldn't have anywhere near enough time for the bolt to unlock before catastrophic damage occurred. I don't see how that would make any difference except to provide a whole lot more little pieces of schrapnel than a few monolithic pieces.
But it sure sounds like a good idea for a video....
The Barrett also probably blew up before it hit the same pressure levels as the RN50 which means the shrapnel was less energetic. But this also means weaker loads of degraded/tampered ammo will still send shrapnel at you in a Barrett, whereas an RN50 might be ruined but intact. You could also be more confident in your own wildcats with an RN50
We know the barrel was not obstructed. So, I'm not sure what the shooter could have done that made it operator error.
I have a very hard time believing the round that blew up the RN50 was a factory round. The most likely situation seems to be that it was a reload and the reloader made a mistake. The seller may not have even know it was a reload. If factory ammo was as hot as that round, you'd have seen news stories or field reports of machine guns blowing up. Now the failure might have been less dangerous. Because the machine gun is much larger and not meant to be man portable. But put a pipe bomb in a gun and it will go boom.
@@DeadeyeLefty kentucky ballistics blew up a barrett. it sent deadly sharpnel into the dummy. on a bolt action the entire bolt would have gone into the users face
On a note of being cautious about where ammo comes from, I never understood gun tubers shooting objects viewers have sent in. 🤔
Well, you're supposed to be at a safe distance.
Man I can't imagine having a company and dealing with an issue like this. With how people are so willing to internalize their first instinct and then dismiss anything that could challenge that thought, really fighting an uphill battle even if you are completely in the right.
I am not dismissing new evedence, but I don't think the owner of the company should be labeling potential costomers as stupid for asking more detailed questions.
You could have threaded the outside of the entire barrel and make a 33.41" long threaded end cap and that gun would have still blown up. Might be a fun project just to prove a point though!
No
Not an engineer but your analysis along with Scott's followup videos make it clear to me that the slap round was crazy overpressured and nothing but an adamantium action and barrel reinforced with vibranium could have survived it.
The tribalism comment is 100% truth and continues to be to our detriment as a whole (as a gun community and as society ingeneral)
A similar thing happened to a factory 30-06 rifle with factory 30-06 ammo.
It turned out the ammo and rifle were in the truck, on dirt roads, for 30-40k miles.
The powder rids broke-up into a small flake size, significantly increased the burn rate.
I believe this is what happened to the 50 BMG rifle using surplus ammo of questionable storage and transportation.
Yeah I remember when Scotts accident first happened I saw a comment guessing that whoever sold him the ammo was probably running them as whole cartridges through a case tumbler to make them look nice and shiny. Would love to see that theory tested.
the slap round that blew up Scott's RN-50 would have grenaded ANY .50 BMG rifle. Scott proved this in his own videos lol. i suspect it would even grenade a modern M2. i'd be interested to see ANY chamber that could handle those pressures. in fact, i think a purpose built canon that had a welded on breach would have to be impressively thick to safely fire that slap round. The more interesting question to me at this point is where exactly that slap round came from? was it one of the mythical sabotaged rounds that the CIA supposedly fed into foreign markets? Was it a hand load made by a half asleep moron? was it a factory round that got the wrong propellent somehow?
For firing with a 10cm barrel out of a block of steel?
The term you're missing is failsafe. Compare RN50 failure with Barret failure. RN50 threw a cap right at shooter's face while barret did a decent job of deflecting the fragmentation upwards and sideways away from shooter's face due to its enclosed design aka receiver.
Because organic chem is crazy could just be decomposed propellant in a bad way.
I agree that the round was way over pressure and that the rifle was not at fault. However, Scott's "test" was proved nothing. It was fun to watch though. All he proved was that an extremely overpressure round can destroy any rifle. It didn't provide any comparative data between the two designs or data on the original slap round in question. Imagine if i wanted to test two different beer can designs for strength so i dropped a bulldozer on each. They both get crushed so i determine that they have equal strength. Do you see the problem?
Could also be because of age. Some gunpower gets unstable after a while. (depending on storage conditions) I imagine that could be a huge problem on a round like this.
"Fail safe" doesn't mean "can't fail", it means when it does fail, it fails in a way that's relatively safe. I would be thinking of something that deflects or catches a broken part. Like in the barett video more of the energy goes into bending/destroying the receiver rather than throwing a loose part towards the shooter. But that is just a natural consequence of the semi-auto being more enclosed; I understand you have a high safety factor and shouldn't need this.
Yeah I’m pretty shocked Mark has misunderstood that term and concept so completely. Failsafe is great and has been in firearms designs for over a hundred years. IIRC Ian or Ian’s comments mentioning old Mauser actions having an intentional blowout point for overpressures.
He went on a tangent and explained it poorly, but I think he knows and that's what he meant. No system can fail completely safely from all possible causes of failure. The fail-safe itself is a system, that system has limits, and it too can fail. Put enough weight on an elevator and you'll see even the brakes won't hold forever.
Case in point: when Mark talked about the ears, brittle vs soft. The ears are already a fail-safe system by themselves, for the threaded cap of the action. But then he considered what would happened if the ears sheared - so a failure of the fail-safe - and the consequences of hardening that part: it makes it less safe on failure.
I think the respect for the raw power of .50bmg gained from Scott’s accident was overall a positive thing, glad he is alive and well, and it’s unfortunate that you and your business have been blamed for what happened, by the people who are just there with an opinion based on little fact, the RN-50 is like a child of yours from a business standpoint. And a severely over pressure round would turn any man portable firearm into a pipe bomb, hell even a M2 would have failed catastrophically from something that overpressure, and that’s the gun literally designed for .50BMG, don’t let the hate out there get to you to much Mark some people just want to be angry at something because they can act like an expert and feel somehow validated by throwing shade at someone who literally engineers firearms for a living. Good on you for letting most of it roll off your back, never stop chasing your passion. ✌️
Hi Mark, appreciate the videos. I think more importantly than “fail-safe” is mitigating the worst effects of certain failure modes (FMEA). As engineers, we should be concerned with mitigating effects to operators given a particular failure mode. An example of this is the M1 Abrams. Those engineers didn’t pretend that they can prevent an explosion inside. Instead, they mitigated the effects of an explosion by keeping the ammunition in a blow-out compartment. Maybe there are similar steps you can take in future designs to mitigate the effects of the worst failure modes.
What you are describing, are fail-safe systems. Fail-safe does not mean fail-proof. It means that when a fail happens, it happens in the least worse possible way. Those blow-out compartments are fail-safe systems as they are supposed to mitigate the possible consequences by redirecting the blast force away from the crew.
It was the ammo not the gun
@@anteshell Yup, totally get that, was just using fail-safe in the context that mark used it.
As someone who does fail-safe electrical engineering (railroad), you try and make the failure mode as predictable as you can. For vital systems, we have to be one point safe - one component can fail, and the system does not result in loss of life (nuclear weapons are two point safe, and aircraft may have higher margins). You cannot always protect against a wrong-side failure (i.e. wiring defect, turning over a device to nullify gravity), but procedures safeguard that.
It definitely is not as simple as making everything as strong as possible. Hardened steel on failure fractures into jagged pieces (and make deadly spall projectiles). A rigid cockpit in a car will transfer all energy in one jolt to the driver. That's why there is materials analysis. Crumple zones in car stretch out the force a bit, and absorb some of it. You want a power plug to pull out before the wires get pulled out of their insulation.
Fuses are an example of a fail-safe. They won't stop an appliance from getting destroyed by a lightning strike, but they'll stop a zapped appliance from being a fire hazard if it was shorted by the event (for the railroad, lightning and electrical arcs are our biggest concern. We use carbon because it doesn't weld, and silver because it conducts the best in our contacts. We also use lightning arrestors frequently on top of that.
Mechanical fuses are not unheard of. That seems to be the way to go if you can. Everything has to be stronger than the fuse link. There is a curve of velocity against mass here, where less mass can have more velocity. You might want to take a bigger amount of force spread over a wider area at a reduced velocity than a small mass high-speed (shrapnel) part. If you take a cable snapping as an example, there is a difference between letting it break in the middle somewhere as opposed to having it fail at the shackle or loop (an example is an elevator on one side of that cable, the cable failing away from the cab is better than towards it).
Sure, it's not guaranteed to work if you run into a big enough idiot who uses it to lift a neutron star, but it's not hard to do.
Yeah he can, stamp on the barrel "non standard ammo voids warranty" lol
my understanding of Ian's "fail safe" comments are as to how the gun fails. example, the ar15 is designed in a way that the upper receiver will blow away from the shooter when it fails.
The Barrett being semi auto (& costing alot more money) failed in a much safer way with its huge plate sheild on top.
Thanks Captain Obvious
Not every weapon is that enclosed; a bolt action rifle would have sheared the lugs and sent the rest of the bolt back into shooters head. And AR style can injure people plenty with serious failures. If it’s overpressure enough to shear the lugs, bolt carrier can depart the back of the rifle into your shoulder.
There isn’t an action that’s inherently safe. You can set a higher safety standard pressure to design everything to, say the 200k PSI of pistol powder in rifle or of an intentionally sabotaged cartridge, but you won’t enjoy the resulting gun sizes or weights.
@@steezydan8543 I’m confused what you’re saying here. .50 BMG is normal round maximum ~55,000 PSI proof pressure 65,000 PSI. 5.56 & 223 … is normal round maximum at 55,000, proof pressure 65,000.
There’s less chamber cross section area so much less force, but that’s different.
When something had reached the muzzle break, the energy would have been spread and a piece of plastic wont hold any kind of force coming out of the barrel.
Sabot rounds for 50 cal are only used on HB, you can find the people who were shooting tungsten with the M2HB with a scope with SLAP sabot munition.
yeah if the round can punch through an inch of steel that little bit of red plastic isnt doing shit.
Only thing I can think of is if in a Barrett a Sabot was fired and it left a piece of plastic at the muzzle end, then sometime after another round fired and it led to an issue, but even then, doubtful.