First AR pistol "build" tips and ideas

[MistWolf]

AR pistols with a 22 conversion kit are awesome!

 

[Gtscotty]

I suggest you go experiment with your 18" upper. Shoot it in it's current state of tune, paying attention to how sharp the recoil feels. Then, Now, put a single round in your magazine and load the rifle and shoot it. Keep closing of the gas until the rifle ejects, but does not lock back. Then, open your gas block one click and test to make sure the rifle ejects and locks back. Run 10 or 20 rounds through it, noting how the recoil feels. You'll notice it feels softer (unless you're running a carbine weight buffer. If you're running a carbine weight buffer, get replace it with an H or H2 buffer).

I've played with the gas flow and know how it can affect the recoil impulse of the rifle on longer barrels and gas systems. I'm not very familiar with carbine length gas systems on 10.5" or 11.5" barrels, and didn't know whether they were more finicky about gas settings. It doesn't seem like there's much time for the gas to act after the bullet passes the port, but before it exits the barrel.

The subsonic aspect of 300 BLK is interesting, the part that bothers me is that .30 bullets, especially the heavy bullets suitable for subsonic use are so much more expensive than .224 (I buy 55gr SP's for $0.10 per or less all the time). Sending 208gr ELDs or 220gr SMKs into a berm 100yds away seems like a waste when I could use similarly priced bullets for LR loads in my 6.5s or .308. I know they make coated lead bullets for cheaper, but my can is sealed so I'm not too keen on getting a bunch of lead buildup.

I hadn't really considered a stubby .22lr upper, but that might be a lot of fun.

 

[MistWolf]

Because the shorter gas system operate at a higher pressure, smaller changes have a greater impact and the optimum range is tighter.

The gas does not act on the system until the bullet leaves the muzzle. The system uses the gas literature left in the bore after the bullet has uncorked the muzzle. If the gas were to act on the system while the bullet was in the bore, suppressors would not change carrier speed.

For 300 BLK subsonic rounds, I think I'd use 220 grain round nose bullets for greater thump. But, if you see see no reason to run a 300 BLK, or have any desire to give it a try, your decision is already made. Drop it from your consideration.

 

[JShirley]

I bought one of the SB3 kits from PSA, and have a pistol length .300 upper from Hardened Arms coming.

Turns out that suppressed hunting is now legal in GA and AL.

 

[someguy2800]

Just for inspiration this is my side charging 9mm AR pistol I built this spring. Love it. Everyone that shoots it loves it. I took it on a camping trip this weekend and stowed it in a small bag in the boat. Its a 10.5" barrel with a krink brake under the handguard.