Amazon has some really inexpensive ($20-30)5mm diameter wifi/bluetooth dual camera borescopes that allow you to look through the barrel to check the gas block alignment. Saved me tons of frustrations with gas block alignment.
Pin gauges are the best way to measure gas port diameter. For 16" mid length I wouldn't go beyond .076. I had to drill out a 20" Faxon barrel for the same reason. You used a cleaning rod like I do to protect the bore, good job..Nitride barrels are a lot harder to drill, so I grind just the top of the barrel port to knock off the hard metal surface so the drill bit won't chip or break..
I have several Bear Creek Arsenal uppers. They run fine. But, I bought a 450 Bushmaster that won't cycle right. Every forum I've been on suggests a heavier buffer. I went with an H3 with no change. So, I'm pretty sure my gas port is undersized. Just haven't drilled it yet. Thank God this is a parkerized barrel, not nitrided.
Good luck. If it's really, really under gassed you can jump 0.010". If it's just a little undergassed you might want to just go about 0.005" and check.
I have a couple of home builds with exactly the same issue, I have tried EVERYTHING (swapping buffer/spring, BCG, different ammo, checking for proper gas block alignment, for any BCG dragging inside the upper etc) Although it's the last thing I wanted to do, I think I will have to do the same thing
@@retro9590 I get these from MFIAP dot com. They make parts for people to get around the 922 laws. I think this is some HK type flash hider. Good solid kit, I get their clearance ones bc they are a little spendy.
I had trouble with 300 blk out. People that sell barrels dont tell gas port size but some do. I found gas port size is all over the map. I bought one barrel where they stated they opened them up because manufacturer made the port to small.
some barrels seem to be anticipating a suppressor on them, which would generally require less of a gas port. Seems silly to me to not err on the larger side, overgas the gun and let people put an adjustable on it to lower the volume.
I tried this idea a few years ago. It made my BCG all ickey and barely able to charge it. I ended up with an adjustable gas block and a 3oz buffer. It was for 300BO.
I'm glad it worked for you, however, a fixed gas block provides more gas than an adjustable, as adjustables can only by definition go down from 100%. The buffer change likely helped a lot.
I bought a Ballistics Advantage 18" rifle length gas system barrel in .308. It has been a nightmare! I paired it with a rifle length buffer and tube. Right away it was short stroking. Usually after about 10 rds and bam! Bolt wont lock back. I changed gas blocks etc...etc. I went through it by the numbers. The BA barrel I bought is supposedly .089 at the port. I read that it should be .096! My rifle is under gassed and I've spent over $200 in ammo to realize it was the barrel port! Uuugh. Barrel is great however. I get bullets stacked and touching each other at 50 yards. Tomorrow I will be drilling out the port!
@@bigger62265 Yes they are all too small. I have to drill them all. Wire gauge numbered drill bits. I called BA and they said they are drilled proper and tested gas port sizes. They are wrong. I wonder if BA is drilling for suppressor use.
@@bfdadventure i think they are. My 13.7 with and adjustable gas block all the way open runs "mostly" reliable but I have to use an ar-15 cut bcg... the majority of high quality durable and affordable ones are full auto cut... suppressed it's no issue, but I'd rather turn down the block than have to run suppressed 100%. Suppressed I can tune it down but without i occasionally don't get bolt locking back on last round. If I ran lesser loads, I'd have issues for sure. Solgw has their gas port sized larger than BA for these very reasons. You don't want something that's mostly reliable, you want something always reliable without question.
I have the same barrel and same problems. I found this video because I’m going to drill mine out. I measured my hole and it’s .0785-.08. Way under what it should be like you said.
You think the manufacturers would know. a bought a 20” ss bca in .308 with a rifle length gas system in the specs it said the gas port is drilled out at .086”. This is the first Barrel I have ever bought so I was having faith the manufacturer had done the research 🧐 now I know why my rifle is short stroking! Not by much though, just enough to damage the second round in the mag and to not keep the bolt open on the last round.
Sorry about your luck :( Make sure you check everything else before taking a drill to your barrel and check for burrs inside the bore after you are done. Worst case scenario you get a burr and you need to remove it before shooting the firearm.
Mine will keep bolt open on last round but 9 out of 10 times won’t feed another round into chamber.. you would think the mags right? But I can manually charge it and it chambers just fine. Any ideas?
@@huntergardner597 when you load the last round into the chamber, remove the mag and see if it still holds the bolt back That will tell you if the bolt is catching on the back of the mag or actually catching on the bolt catch.
After my own recent experience and reading yalls comments i feel like most manufacturers drill their holes too small....cept ironically the cheap barrels...
I’ve got a 24” 6mm arc and shooting suppressed. Still will not cycle and I have a new aero adjustable gas block brand new BCG and gas tube. I guess this is my next step
How /where do you find out what size the port in the barrel is suppose to be for it's caliber and length. I did a build with AR stoner parts . 24" SS bull barrel. I put an adjustable gas block on it and no amount of adjustment made it cycle reliably. Undergassed. So I adjusted the gas block full open and dropped the buffer weight from 5 1/8 oz. to 4 1/16 oz . Now it cycles every round and stays locked open after last round but casing are at 4:30-5 o'clock.
You can email barrel manufacturers and ask what they would use for that length barrel and whatever gas system you have on it. You can also maybe ask the guy at AR15barrels or RetroArmsWorks what they might suggest for a diameter. They are both really good guys and might be able to help you out.
Great video! I have a couple of home builds that I KNOW I have eliminated all other issues and this is what I need to do. Do you need to use a cobalt drill bit?
Hello, just built an ar-15 and it is not cycling, I'm only able to fire one round at the time but it does gets the next round ready in the chamber. I think The ejector is working fine because the empty roung comes out after it fires. Tested my upper with another lower receiver and it worked good but when tested my lower with a different upper receiver it would not work. Please help
Hello, please look at your hammer springs, carefully inspect how you installed them and make sure they are installed correctly. It sounds like your trigger is not resetting properly. If you have a cartridge trigger, make sure the pins are solid. Good luck.
Same issue with my aero 18 inch upper. It's a stainless 223 wylde qpq coated barrel. Rifle length gas system. What size should I drill it out too? I have seen charts for 16 and 20 inch but no 18 inch barrels. Thanks
I'd probably look to the larger end of the 20" rifle gas diameter range, whatever that might be. Probably around the same size as mine is or a little smidge bigger. I looked at arfcom for you and they are saying in the 0.090" range. No harm in going 90-95 in my opinion.
Did you resolve your issue? I have an Aero 18 SS 223 wylde fluted barrel in a newly built upper and having cycling issue. It's rather weird. It will cycle a 75 grain Federal cartridge, but will not cycle the 62 grain Hornady. Very bizarre to me.
@dickjohnson7845 it ended up working itself out. I never messed with anything. I put about 250 rds or more through it and it started cycling fine. Now I'm at about 500 rds or so with no issue. I've tried every grain weight that I could find and still no issue. I went to a gunsmith and he told me to break it in before I come to conclusions. He was right. Hope you figure out the issue
always use drill bit to ck hole size,if not cycling,drill bigger .010 bigger then test,if u get big as .100 inch,ck 4 other problems,i had to take a .110 out on an ar10/bc 308,n it worked perfect,may be too big,but,i'm goin to order adj blk antway,shells landing at 4 o;clock/good w/ my reloads,may need to slow down w/other loads,most ar15 bbrls r drilled bout .060 frm factury,dep on gas leanth have fun
No actually there is a standard size gas port. Some manufacturers undersized the ports to accommodate for suppressed use. .30 caliber is common. .300 blk. And .308
In practice, there are somewhat standardized gas ports, but they vary for barrel length/gas system length combinations. Throw in 6.8SPC or 22 Valkyrie and no, the gas ports are not going to be precisely standard. Unless all you purchase are 16" 5.56 NATO barrels with carbine length gas ports.
You can find it on hkparts (dot) net with the SKU of HKP-17941. It was very difficult to find for sure. It is made by MFIAP (dot) com. Very good folks.
@@Bagheera2 they are the 1/2x28 that a normal 223 AR would have. There are different threads for different calibers once you get up to the 6.5s and up.
Likely you could have lightened the buffer... Maybe a 3oz instead of a standard 5oz rifle buffer... Barrel makers deterring the port size based on barrel use, length and dwell..
HOW DO YOU DE BURR THE INSIDE OF THE BARREL AFTER YOU DRILL THE PORT OUT? I have watch many videos about under sized gas ports and drilling the gas portslarger. BUT no one has addressed, in detail, how to remove the burrs that are possibily left on the inside of the barrel after drilling. Eveybody talks in detail about port size, how to use a drill, how to keep from drilling to deep, what to use to keep from drilling to deep. BUT nothing about how to de burring the inside of the barrel. You will be instructed to de burr, and thats about it.
@@Level-zb4jg they inspect for large burrs, and may go in after them with a nylon tool, but most people who are just making the existing port a tiny bit larger do not have major burr issues that patches can't clean out.
@@koffeekage it's all good, you make a good point, if I had one I would have used it. The shop at work is where a lot of my stuff gets done, but I can't bring a rifle barrel in there :S
It's possible, but from the first round it was not running and it was a little undersized from the small sample size of help I got on arfcom. Good point though!
Amazon has some really inexpensive ($20-30)5mm diameter wifi/bluetooth dual camera borescopes that allow you to look through the barrel to check the gas block alignment. Saved me tons of frustrations with gas block alignment.
I’ve used a piece of spaghetti before and it worked
Pin gauges are the best way to measure gas port diameter. For 16" mid length I wouldn't go beyond .076. I had to drill out a 20" Faxon barrel for the same reason. You used a cleaning rod like I do to protect the bore, good job..Nitride barrels are a lot harder to drill, so I grind just the top of the barrel port to knock off the hard metal surface so the drill bit won't chip or break..
100% agree with the pin gages.
I like the cleaning rod thing
I have several Bear Creek Arsenal uppers. They run fine. But, I bought a 450 Bushmaster that won't cycle right. Every forum I've been on suggests a heavier buffer. I went with an H3 with no change. So, I'm pretty sure my gas port is undersized. Just haven't drilled it yet. Thank God this is a parkerized barrel, not nitrided.
Good luck. If it's really, really under gassed you can jump 0.010". If it's just a little undergassed you might want to just go about 0.005" and check.
@@shortreloadingvideos7571
Thanks!
I'm in the same exact situation at you, hopefully drilling a larger diameter gas port will solve the problem.
Good content & great explanation. Going thru the same trails & tribulations w my new upper. Thnx
Thanks, and me too with a 45 Raptor upper :S
Thanks me to with a Aero precision m5
I have a couple of home builds with exactly the same issue, I have tried EVERYTHING (swapping buffer/spring, BCG, different ammo, checking for proper gas block alignment, for any BCG dragging inside the upper etc) Although it's the last thing I wanted to do, I think I will have to do the same thing
It was the most frustrating thing so far for me. Go slow and put something in the barrel to protect it and you will do fine.
Check the magazine
@@originalgangsta5462
I tried several. Ended up opening up the gas hole and it ran like a champ!
Sounds like we should start with whatever is the cheapest fix first. I'm right there with you.
Thanks so much for the info. This helped me out a lot
Having the same issue with an aero 18 inch spr upper, tried everything but this, if that’s the case easy peasy. Thanks for sharing
Nutnfancy fought with one short cycling for years and this was the fix. Cool rifle btw I like that handguard.
@@retro9590 Thank you, I shopped hard before settling on that handguard. Yes it was an easy fix and it was immediately resolved.
Do you have name of or link to that muzzle device?
@@retro9590 I get these from MFIAP dot com. They make parts for people to get around the 922 laws. I think this is some HK type flash hider. Good solid kit, I get their clearance ones bc they are a little spendy.
@@shortreloadingvideos7571 mine just came in today, looks great on my aero spr 18 upper. Thanks man
I had trouble with 300 blk out. People that sell barrels dont tell gas port size but some do. I found gas port size is all over the map. I bought one barrel where they stated they opened them up because manufacturer made the port to small.
some barrels seem to be anticipating a suppressor on them, which would generally require less of a gas port. Seems silly to me to not err on the larger side, overgas the gun and let people put an adjustable on it to lower the volume.
I tried this idea a few years ago. It made my BCG all ickey and barely able to charge it. I ended up with an adjustable gas block and a 3oz buffer. It was for 300BO.
I'm glad it worked for you, however, a fixed gas block provides more gas than an adjustable, as adjustables can only by definition go down from 100%. The buffer change likely helped a lot.
I bought a Ballistics Advantage 18" rifle length gas system barrel in .308.
It has been a nightmare!
I paired it with a rifle length buffer and tube. Right away it was short stroking. Usually after about 10 rds and bam! Bolt wont lock back.
I changed gas blocks etc...etc.
I went through it by the numbers.
The BA barrel I bought is supposedly .089 at the port. I read that it should be .096!
My rifle is under gassed and I've spent over $200 in ammo to realize it was the barrel port!
Uuugh.
Barrel is great however. I get bullets stacked and touching each other at 50 yards.
Tomorrow I will be drilling out the port!
Same....but with a 6" 300aac BA barrel. Apparently the gas ports are consistenly too small for reliable cycling on a variety of BA barrels.
@@bigger62265 Yes they are all too small. I have to drill them all. Wire gauge numbered drill bits. I called BA and they said they are drilled proper and tested gas port sizes. They are wrong. I wonder if BA is drilling for suppressor use.
My 16” 308 barrel is 73
@@bfdadventure i think they are. My 13.7 with and adjustable gas block all the way open runs "mostly" reliable but I have to use an ar-15 cut bcg... the majority of high quality durable and affordable ones are full auto cut... suppressed it's no issue, but I'd rather turn down the block than have to run suppressed 100%. Suppressed I can tune it down but without i occasionally don't get bolt locking back on last round. If I ran lesser loads, I'd have issues for sure.
Solgw has their gas port sized larger than BA for these very reasons. You don't want something that's mostly reliable, you want something always reliable without question.
I have the same barrel and same problems. I found this video because I’m going to drill mine out. I measured my hole and it’s .0785-.08. Way under what it should be like you said.
Great Video!!!
If you put it in a drill press you can set the depth limit.
You think the manufacturers would know. a bought a 20” ss bca in .308 with a rifle length gas system in the specs it said the gas port is drilled out at .086”. This is the first Barrel I have ever bought so I was having faith the manufacturer had done the research 🧐 now I know why my rifle is short stroking! Not by much though, just enough to damage the second round in the mag and to not keep the bolt open on the last round.
Sorry about your luck :( Make sure you check everything else before taking a drill to your barrel and check for burrs inside the bore after you are done. Worst case scenario you get a burr and you need to remove it before shooting the firearm.
Mine will keep bolt open on last round but 9 out of 10 times won’t feed another round into chamber.. you would think the mags right? But I can manually charge it and it chambers just fine. Any ideas?
@@huntergardner597 when you load the last round into the chamber, remove the mag and see if it still holds the bolt back
That will tell you if the bolt is catching on the back of the mag or actually catching on the bolt catch.
Exact same thing my FN barrel was doing on a 10.5 pistol.
After my own recent experience and reading yalls comments i feel like most manufacturers drill their holes too small....cept ironically the cheap barrels...
I’ve got a 24” 6mm arc and shooting suppressed. Still will not cycle and I have a new aero adjustable gas block brand new BCG and gas tube. I guess this is my next step
Good luck!!
How /where do you find out what size the port in the barrel is suppose to be for it's caliber and length.
I did a build with AR stoner parts . 24" SS bull barrel.
I put an adjustable gas block on it and no amount of adjustment made it cycle reliably. Undergassed.
So I adjusted the gas block full open and dropped the buffer weight from 5 1/8 oz. to 4 1/16 oz .
Now it cycles every round and stays locked open after last round but casing are at 4:30-5 o'clock.
You can email barrel manufacturers and ask what they would use for that length barrel and whatever gas system you have on it.
You can also maybe ask the guy at AR15barrels or RetroArmsWorks what they might suggest for a diameter. They are both really good guys and might be able to help you out.
Got an upper with a 10.5 FN button cut barrel with the same issue, going to try and take it up to .070 and see what happens
I think I have it with a 45 Raptor right now, probably going to drill it out
Great video! I have a couple of home builds that I KNOW I have eliminated all other issues and this is what I need to do. Do you need to use a cobalt drill bit?
No I used cheapo Walmart drills and they worked well.
You’re not removing much at a time they will make it
Thank you
Hello, just built an ar-15 and it is not cycling, I'm only able to fire one round at the time but it does gets the next round ready in the chamber. I think The ejector is working fine because the empty roung comes out after it fires. Tested my upper with another lower receiver and it worked good but when tested my lower with a different upper receiver it would not work. Please help
Hello, please look at your hammer springs, carefully inspect how you installed them and make sure they are installed correctly. It sounds like your trigger is not resetting properly. If you have a cartridge trigger, make sure the pins are solid. Good luck.
@@shortreloadingvideos7571 thanks I'll do that now and test it tomorrow ☺️
Same issue with my aero 18 inch upper. It's a stainless 223 wylde qpq coated barrel. Rifle length gas system. What size should I drill it out too? I have seen charts for 16 and 20 inch but no 18 inch barrels. Thanks
I'd probably look to the larger end of the 20" rifle gas diameter range, whatever that might be. Probably around the same size as mine is or a little smidge bigger.
I looked at arfcom for you and they are saying in the 0.090" range. No harm in going 90-95 in my opinion.
@shortreloadingvideos7571 thanks alot for the info. I will give it a try. Merry xmas!
@@mattstaab6408 Merry Christmas Matt!
Did you resolve your issue? I have an Aero 18 SS 223 wylde fluted barrel in a newly built upper and having cycling issue. It's rather weird. It will cycle a 75 grain Federal cartridge, but will not cycle the 62 grain Hornady. Very bizarre to me.
@dickjohnson7845 it ended up working itself out. I never messed with anything. I put about 250 rds or more through it and it started cycling fine. Now I'm at about 500 rds or so with no issue. I've tried every grain weight that I could find and still no issue. I went to a gunsmith and he told me to break it in before I come to conclusions. He was right. Hope you figure out the issue
The proper way to measure a gas port is using pin gauges.
That would be important if the gas port had a tighter tolerance than ~8 thou
Eye ball is good enough, not everyone has a high roller tool chest
And a couple other ways. Obviously
Would a dimple jig help somehow to keep you drilling straight down!
It's possible, but the hole is only being expanded 5% or less, there is a substantial pilot hole.
always use drill bit to ck hole size,if not cycling,drill bigger .010 bigger then test,if u get big as .100 inch,ck 4 other problems,i had to take a .110 out on an ar10/bc 308,n it worked perfect,may be too big,but,i'm goin to order adj blk antway,shells landing at 4 o;clock/good w/ my reloads,may need to slow down w/other loads,most ar15 bbrls r drilled bout .060 frm factury,dep on gas leanth have fun
I like the hand grip hardware, what company makes that?
Thanks
That is a PRI Delta
No actually there is a standard size gas port. Some manufacturers undersized the ports to accommodate for suppressed use. .30 caliber is common. .300 blk. And .308
In practice, there are somewhat standardized gas ports, but they vary for barrel length/gas system length combinations. Throw in 6.8SPC or 22 Valkyrie and no, the gas ports are not going to be precisely standard. Unless all you purchase are 16" 5.56 NATO barrels with carbine length gas ports.
I want that flash hider
You can find it on hkparts (dot) net with the SKU of HKP-17941. It was very difficult to find for sure. It is made by MFIAP (dot) com. Very good folks.
@@shortreloadingvideos7571 standard ar thread pitch?
@@Bagheera2 they are the 1/2x28 that a normal 223 AR would have. There are different threads for different calibers once you get up to the 6.5s and up.
Likely you could have lightened the buffer... Maybe a 3oz instead of a standard 5oz rifle buffer... Barrel makers deterring the port size based on barrel use, length and dwell..
They said these were overrun of a special batch and the holes were made small.
I got a new Faxon 18" full-length gas, and the hole is .094
Thanks for that info, a guy was just asking about 18" Rifle Length gas ports
HOW DO YOU DE BURR THE INSIDE OF THE BARREL AFTER YOU DRILL THE PORT OUT?
I have watch many videos about under sized gas ports and drilling the gas portslarger. BUT no one has addressed, in detail, how to remove the burrs that are possibily left on the inside of the barrel after drilling.
Eveybody talks in detail about port size, how to use a drill, how to keep from drilling to deep, what to use to keep from drilling to deep. BUT nothing about how to de burring the inside of the barrel. You will be instructed to de burr, and thats about it.
How do you think they do it at the factory?
If I knew I wouldn't be asking.
I'd run a brush through a bunch and follow it with some patches.
@@Level-zb4jg they inspect for large burrs, and may go in after them with a nylon tool, but most people who are just making the existing port a tiny bit larger do not have major burr issues that patches can't clean out.
Why not use a drill-press?
The same reason I didn't use a Fanuc Robodrill.
Don't have one.
@@shortreloadingvideos7571 i guess i hadn’t considered that.
@@koffeekage it's all good, you make a good point, if I had one I would have used it. The shop at work is where a lot of my stuff gets done, but I can't bring a rifle barrel in there :S
If you have the barrel on correctly why would you want to take it off just to in large it just a few thousands of an inch ?
The gas hole may have been lead fouled
It's possible, but from the first round it was not running and it was a little undersized from the small sample size of help I got on arfcom. Good point though!
the worst way to drill a gas port ..use pin gauges, not a vernier.
Worked well too