You should talk to KAK about making what you need. KAK is the most innovative company in the AR game. Those guys make their products in house and the quality is #1.
I want to build one, but with the KAK very short barrel. I built a short barreled 5.56 pistol and it works. I had to dig a channel in the barrel nut to fit but it works well, though I didn't use the short buffer.
@blowback9 Theoretically speaking, would their be any issues using the Law Tactical folding stock adapter with this K Mini buffer tube with your GRS and soon to offer tungsten weights?
Will a standard 3.25 buffer fit in the mini tube and allow enough travel for the bolt to lock open? Also, since the kak mini PCC buffer is longer than the 556 buffer, is it possible to replace the flat wire spring with a standard carbine spring and not reach solid height? And if so, a 308 AR carbine spring should have about the same solid height but more spring tension. Anyway. Food for thought. I found this video absolutely incredibly helpful, and I think the timing is just crazy considering I'm currently building an EPC 9 and looking at the kak mini buffer system. I'm trying to take this one step further and add a law folder Brace as well. I will have to modify the weight on the back of the EPC 9 bolt to fit the buffer extension of the law folder. But I think it would be a rather interesting build. Thanks so much for the very informative video!
A normal carbine buffer will short stroke the bolt, but it will work just without bolt hold open. A Taccom or other short stroke bolt may still allow the bolt hold open to work. I'll have to try it. Not sure on the spring, but I'd definitly not use a .308 spring in a 9mm AR. The short buffer already provides additional spring tension, and .308 springs are correlated with a number of serious problems in a 9mm AR.
I've been wondering if there is a negative consequence if the stock Bolt weight is replaced with a KAK tungsten bolt weight. In your video when you were talking about the KAK tungsten bolt weight you stated (time stamp 10:40): "if it's installed backwards it's going to abuse the snot out of the Pin even worse than it will already" implying that even if not installed backwards, some abuse of the Pin will still occur. If the KAK tunsten bolt weight is (correctly) installed, does the additional weight "abuse the Pin" when the Bolt slams shut because the Pin now has to stop the additional weight from trying to slide forward in the Bolt? If not, is there another negative consequence to using a Tungsten Bolt weight? Do you prefer to not using a Tungsten Bolt Weight? Thanks!
I'm told the KAK tungsten weight is designed to sit flush in the rear of a KAK bolt. The extra mass of the tungsten weight is rough on the pin due to momentum of the weight. With the KAK bolt, during the rearward stroke it is up against the buffer, taking some stress off the pin. In other bolts it sits recessed in the bolt, so when the bolt stops rearward, the weight wants to keep going with nothing to stop it except the pin. On the forward stroke the pin always has to stop the weight since anything in front would interfere with the hammer channel in the bolt. A coiled roll pin would provide extra strength and protection against shearing, but they don't provide one.
Did you use a muzzle brake or a suppressor/ gun muffler. I think any blowback will be snappy without a brake on it. Nice work very informative and detailed. Thanks for the info
I did not. 9mm produces little gas to work with, so a top-only or side-only brake tends to work best. I don't have any, though. I'll add that to the growing list!
KAK flat wire carbine spring is a good match. 9mm blowback only needs a standard carbine strength spring, nothing more, even with ridiculous amounts of weight. I just ran a test with 43+oz. (over 2.5lbs!) of mass using a standard stainless steel M4 carbine milspec spring. Ran perfect.
Can’t the buffer weight be made out of a material giving the weight you get with the spacers? Then tube and spring (matl/tension) adjusted to length required? Love the concept.
Captured springs are generally a bad idea in a 9mm blowback system. They tend to be very underweight and oversprung. blowback9.wordpress.com/2021/10/27/captured-spring-systems-a-bad-idea-for-pcc/
You should talk to KAK about making what you need. KAK is the most innovative company in the AR game. Those guys make their products in house and the quality is #1.
What a cool concept, abbreviating the buffer tube. Love this channel so much
Excellent content!!
It is interesting to see the red dot moving back and forth when the buffer hits the buffer tube and when the bolt closes!
LOL! Yup, it loosened up. I noticed it when I got home from the range.
Interesting test! 👍
Love the continual research and knowledge sharing - Thx Doug!
Another very informative video, thanks
Great work!!👍🏼
Love the work you do man. Great vid!
I want to build one, but with the KAK very short barrel. I built a short barreled 5.56 pistol and it works. I had to dig a channel in the barrel nut to fit but it works well, though I didn't use the short buffer.
@blowback9 Theoretically speaking, would their be any issues using the Law Tactical folding stock adapter with this K Mini buffer tube with your GRS and soon to offer tungsten weights?
There "shouldn't" be. Haven't tried it yet, so no guarantees.
Will a standard 3.25 buffer fit in the mini tube and allow enough travel for the bolt to lock open?
Also, since the kak mini PCC buffer is longer than the 556 buffer, is it possible to replace the flat wire spring with a standard carbine spring and not reach solid height? And if so, a 308 AR carbine spring should have about the same solid height but more spring tension. Anyway. Food for thought.
I found this video absolutely incredibly helpful, and I think the timing is just crazy considering I'm currently building an EPC 9 and looking at the kak mini buffer system. I'm trying to take this one step further and add a law folder Brace as well. I will have to modify the weight on the back of the EPC 9 bolt to fit the buffer extension of the law folder. But I think it would be a rather interesting build. Thanks so much for the very informative video!
A normal carbine buffer will short stroke the bolt, but it will work just without bolt hold open. A Taccom or other short stroke bolt may still allow the bolt hold open to work. I'll have to try it.
Not sure on the spring, but I'd definitly not use a .308 spring in a 9mm AR. The short buffer already provides additional spring tension, and .308 springs are correlated with a number of serious problems in a 9mm AR.
I've been wondering if there is a negative consequence if the stock Bolt weight is replaced with a KAK tungsten bolt weight. In your video when you were talking about the KAK tungsten bolt weight you stated (time stamp 10:40): "if it's installed backwards it's going to abuse the snot out of the Pin even worse than it will already" implying that even if not installed backwards, some abuse of the Pin will still occur.
If the KAK tunsten bolt weight is (correctly) installed, does the additional weight "abuse the Pin" when the Bolt slams shut because the Pin now has to stop the additional weight from trying to slide forward in the Bolt?
If not, is there another negative consequence to using a Tungsten Bolt weight? Do you prefer to not using a Tungsten Bolt Weight? Thanks!
I'm told the KAK tungsten weight is designed to sit flush in the rear of a KAK bolt. The extra mass of the tungsten weight is rough on the pin due to momentum of the weight. With the KAK bolt, during the rearward stroke it is up against the buffer, taking some stress off the pin.
In other bolts it sits recessed in the bolt, so when the bolt stops rearward, the weight wants to keep going with nothing to stop it except the pin.
On the forward stroke the pin always has to stop the weight since anything in front would interfere with the hammer channel in the bolt.
A coiled roll pin would provide extra strength and protection against shearing, but they don't provide one.
Did you use a muzzle brake or a suppressor/ gun muffler.
I think any blowback will be snappy without a brake on it. Nice work very informative and detailed.
Thanks for the info
I did not. 9mm produces little gas to work with, so a top-only or side-only brake tends to work best. I don't have any, though. I'll add that to the growing list!
@blowback9. Which spring do you recommend with heaviest kak pcc buffer along with the kak 4.5 oz bolt weight? Thanx
KAK flat wire carbine spring is a good match. 9mm blowback only needs a standard carbine strength spring, nothing more, even with ridiculous amounts of weight. I just ran a test with 43+oz. (over 2.5lbs!) of mass using a standard stainless steel M4 carbine milspec spring. Ran perfect.
Where do you buy those tungsten pine wood derby weights?
Search for Pur-Tungsten (.net)
Can’t the buffer weight be made out of a material giving the weight you get with the spacers? Then tube and spring (matl/tension) adjusted to length required? Love the concept.
Yes, the buffer body could be made from tungsten alloy, but it would be very expensive to produce.
Do you think (or will test) the Armaspec Stealth Recoil Spring for 9mm will make a recoil difference?
Captured springs are generally a bad idea in a 9mm blowback system. They tend to be very underweight and oversprung. blowback9.wordpress.com/2021/10/27/captured-spring-systems-a-bad-idea-for-pcc/
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What if you notch the brace so it slides around the locking nut?
Unfortunately, the tube is hitting the backplate of the brace, so it can't go forward any further.
@blow
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