[whatevah]

Pulled the trigger (so to speak) yesterday and bought a nice safe from Cabelas. I've put buying a new gun on hold until I bought a safe for a few months, and while I'm keeping an eye out for a nice .38/.357 lever action carbine, I'm feeling the itch to build an AR pistol.

I don't know too much about the AR pistol ins and outs, but thinking a brace like the SB-15, standard lower, mildly upgraded trigger, adjustable gas block and medium length barrel (10-12"?) with an M-Lok rail and a good flash suppressor. I'll start acquiring parts over the summer and fall, and build it in the winter. As for bolt-on accessories, thinking an angled foregrip (I believe those are legal on a pistol) and good flip-up sights.

I'm looking for any tips you can share, I'm mostly concerned with getting the gas system and buffer matched right. Can you even use an adjustable gas block on a short barrel?

[Owen]

I build a 300 blackout AR pistol with the Sig Brace.

I built it from scratch with a stripped spikes lower receiver, parts kit and complete pistol receiver extension/buffer tube from Viper of course! It all went together easy. As I understand it, the buffer weight, spring and tube all work together so as long as you don't mix and match them you should be fine. I first used a 10.5" barrel and then later an 8" barrel. I was going 300 blackout so I also ran a spikes barking spider krink type break to get better back pressure up for sub-sonic ammo. It shot subs and supers fine.

What caliber are you considering? I don't see why you couldn't use adjustable gas. If you are going 5.56 I've heard they spit fire so you may want a break to help tame that.

[whatevah]

I build a 300 blackout AR pistol with the Sig Brace.

I built it from scratch with a stripped spikes lower receiver, parts kit and complete pistol receiver extension/buffer tube from Viper of course! It all went together easy. As I understand it, the buffer weight, spring and tube all work together so as long as you don't mix and match them you should be fine. I first used a 10.5" barrel and then later an 8" barrel. I was going 300 blackout so I also ran a spikes barking spider krink type break to get better back pressure up for sub-sonic ammo. It shot subs and supers fine.

What caliber are you considering? I don't see why you couldn't use adjustable gas. If you are going 5.56 I've heard they spit fire so you may want a break to help tame that.

I was planning on 5.56, hadn't considered anything else. But, since you mentioned it, i did some quick research and it looks like 300BLK keeps a higher muzzle energy out of a pistol/SBR-length barrel. Hmm... I'd need to get more mags and color code them, but this could be fun.

Thanks for the input! Got any photos of that pistol?

[2xTony]

I built a 556 pistol about 2 years ago and then build a 300blk upper to swap on it. The issue is with the gas block being so close to the chamber it runs a much higher pressure so you have to find a way to slow the whole system down. Mine was having issues at first untill i bought the heaviest buffer i could and also a heavy extractor spring. I was having issues of the bolt moving so fast it would slip off the spent case. Some people solve this problem with one of those gas tubes that wrap around the barrel a few times so its longer and slows the gas down. I domt personally have any experience with them though . 300blk gun will be much more accurate and hit harder if you can afford the ammo. My 556 is basically just a fun toy. Nothing really practicle about it

[Owen]

I was planning on 5.56, hadn't considered anything else. But, since you mentioned it, i did some quick research and it looks like 300BLK keeps a higher muzzle energy out of a pistol/SBR-length barrel. Hmm... I'd need to get more mags and color code them, but this could be fun.

Thanks for the input! Got any photos of that pistol?

Yes 300 BLK works good in a short barrel. Pistol length gas is good for both super and subs. I still have the 10.5 barrel I used if you are interested? I have photos I can post. Just need to get them up online.

[Owen]

I only have pics of the 8" barrel version sans sig brace.



The "spare" barrel I have is here: viewtopic.php?f=36&t=10229&hilit=AR+stoner