Taming gas to face with 9mm ar.

AR/M4 AR Pistols & Pistol Caliber ARs
1

So I just built a new 9mm ar upper. It is a new frontier armory side charging glock upper, with ballistic advantage 8" barrel with a kmr handguard.

I went with a side charging handle to try to tame gas to my face when shooting suppressed(which is most of the time). My previous standard charging handle did give me quite a bit of gas to my face. Unfortunately this set up may be a tad better, but if I do rapid fire, I still get lots of gas to the face. I think most of it is coming out of the ejection port, but it is also seeping out of every other crevice on the pistol also.

I am using a heavy buffer 9q buffer right now. Thinking of jumping up to the 9qt 12.5 oz buffer. Has anyone gone from the 9q to the qt and seen a noticeable difference in gas?

Maybe I should try the scorpion evo and give up on the ar 9 lol.

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2

A heavier buffer should help.

The KAK buffer looks good.

https://www.kakindustry.com/ar-15-parts/lower-parts/buffer-tubes-and-parts/ar15-9mm-buffer-long-heavy

3

That might work. Price is right, but it is only 1.5 oz heavier than what I have.

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4

Are you running a heavy spring also? We often use 308 springs in PCC setups.

5

No Gas Deflector - That’s the problem. You might get unburnt powder & more on ya too.

I have a similar setup in 40SW.
40SW seems to burn powder a bit better.

I am a civilian living in the free state of Kalifornia so 16" barrel non suppressed.
155 / 165gr @1300+ FPS
180Gn @ 1050 - 1100 FPS Subsonic

Slash / Heavy buffers - Special 45ACP buffer 11+ OZ - Didn’t weigh it Heaviest I could find at the time.
Wolf heavy 308 Rifle spring
Heavy Frontier bolt - weight - Kan’t remember.
All of this to keep the bolt closed to burn power.

I now have a heavy Pistol carbine - Heavier than my 5.56.

Colt manufactured a special deflector for their 9mm platform - Not for brass but for gas and powder. I saw a Colt AR 9mm fire out of battery several months ago, If it were not for the gas deflector, the operator / LE would have had brass stuck in his face. I had already purchased my Frontier side charging upper. I have been second guessing my decision ever since but my platform runs like a champ.

6

I am running a wolf Xp spring. Maybe I should give a 308 spring a try.

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7

Considered that also.

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8

https://www.midwayusa.com/product/1015334644/tc-accessories-brass-deflector-ar-15-aWe3-steel-matte

I could try one of these…but ugly though

Really like the nfa side charging upper. Had to tweak the lrbho actuator a bit, but it locks back 100% now.

Maybe I will try the 308 spring, and if that doesn’t work, the heavier buffer, and if still no luck, the brass deflector.

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9

Yeah here is the CMMG version of the “brass” gas deflector and port door. This seems to be a pretty inexpensive item to try first.
https://www.cmmginc.com/product/ejection-port-cover-kit-with-gas-deflector/
and here is what it looks like on a upper receiver.
http://www.primaryarms.com/cmmg-ar-9-upper-receiver-for-9mm-55ba222

BTW Rock River Arms also sells the classic colt style one but you need to buy the port door kit and then buy the gas deflector piece separately.
http://stores.9mmar.com/rra-9mm-ejection-port-door-kit/
http://stores.9mmar.com/rra-9mm-case-deflector-with-spring/