A buddy of mine and I both started building 300 blk sbr’s to run mostly suppressed. He finished his long before me (thanks nfa jail for being so timely) and we shot it recently. Well his DI blew so much gas back into my face while shooting it that I actually stopped because I couldn’t breathe. Does anyone know of any way to resolve/mitigate this issue?
Any help or suggestions would be awesome.
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Well what is your setup and where you suppressed or unsuppressed? Subs or supers?
300s tend to be over gassed.
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Sorry, subs and suppressed. 8.5" barrel aac flash hider for muzzle device, vltor upper, wmd bcg, Samson Evo rails and raptor charging handle. I believe it’s a bcm CH but I know it’s called a raptor. Can is a 762-sdn-6
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One of the differences I was going to explore for my build is a piston upper, pws mk109. But the damned things are so expensive I have to hold off. It’s tough to justify that purchase price when you consider how expensive sub ammo is.
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I have the WMD Nib BCG in my 10.5" so probably not that. Does it cycle properly? Gas block is properly aligned and fitted?
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What brand barrel is he using? I know you said 8.5" but different brands have different sized gas ports.
Cycles like a champ suppressed and un. I believe noveske. Let me check on that.
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Yeah 8.5" stainless noveske, and a pdw arc stock for the buffer setup.
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Read first:
https://www.m4carbine.net/showthread.php?82447-PLEASE-READ-THIS-FIRST-Custom-Build-AR-Forum
Actually the opposite is true. Most 300blk’s are UNDER gassed. The most common complaint “my 300blk wont cycle” and guess what, the gas port is way under sized. Its ALMOST impossible to over gas a 300blk. Its been stated by a few of the high end manufacturers that its actually impossible to over gas a 16" carbine gas 300blk. pistol gas, yea you could over gas it, but not enough to cause gas face IMO.
Pistons have a very shaky history with 300blk. Of all the 300blk stuff out there I think only 1 or 2 have gotten pistons to work acceptably. Even LWRCi, the king of piston builders, was using DI in their 300blk offering(when they were offering it).
Ive got a few rounds(probably over 1k) through a Noveske 8.2"(older barrel) with an AAC 762SDN6 with zero gas face issues. I have no experience with the ARC PDW stock, but seeing how its built and installed on the gun and what not, just from pictures, it doesnt seal the back of the gun very well at all. Its a two piece tube if I am not mistaken and the rear portion of the tube has quite a few vent holes. Again thats going by the pictures. Those vent holes end up right by your face. Where as on a regular stocked gun any venting is done back at the shoulder.
I would suspect the ARC PDW stock as being a or the source of your gas face issues.
Which part are you saying I violated? I basically am going to be building the exact same setup and have 70% of the parts. Also, his is definitely a frankenAR so I’m not too sure what I’m missing here.
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Had my buddy Check the stock and he said there’s no holes except one in the bottom which you depress to hold the buffer tube back (it’s part of the weird way that stock works).
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Highly recommend Applying RTV to your charging handle. This will solve about 70% of the problem - http://www.03designgroup.com/technotes/do-it-yourself-gas-buster-charging-handle
This forum is to show your custom build, not ask questions about one that doesn’t exist. You’ll have better luck in AR General or Technical sections.
Testing would need to be done, but it really seems that the ARC PDW action system would be the issue. For a Noveske, I would personally swap in a A5H2 to test initially to compare. The other action system may not allow enough time to blow out the muzzle before the breach opens.
I’ll give the RTV a shot. That will take a few days possibly a week. I’ll update once we do it.
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Well it DOES exist. I helped him build this one and he doesn’t get on forums. Also, the rules state discuss/ask questions. Not trying to have a pissing match but I’m pretty sure all of what I’m doing and where it’s at fits in the parameters you so kindly pointed me to. Sorry if my posting here offended you somehow but I’m asking the questions about his so I can perfect the build on mine, which he is helping with as well. Hopefully this clarifies your issues with me posting this here.
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Alright. Hopefully going to the range this weekend. we have some other buffers to try and will throw those in to check it out. Same with the RTV trick.
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Didn’t have a chance to get the RTV on the CH and get to the range this weekend. Crossing fingers for next weekend and I’ll post results.
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