7.62x39 AR build

[2A2Dend]

What I have read about building pistols, is they can be finicky. I've built carbines and rifles without problems. Since I haven't built an AR pistol (complete upper was purchased for my first) from scratch, I'm not familiar. And since the 7.62x39 breed can be cantankerous, I don't want to experiment with it. What length? I'm not sure of that either. 12" and below, I guess, because I don't know what the best length would be? I liked the topic you guys had going here, and jumped in!

 

[osprey]

I was considering doing a pistol and sbr'ing it and found a 12.5" barrel with carbine gas system by the same maker as the 16" barrel I ended up using. My 16" is also carbine gas so I would think the 12.5" would run as reliably. They are ER Shaw blanks and the shoot great. I do not have any first hand experience with pistol gas on shorter barrels in 7.62x39 but I see some for sale so I am sure it works as well.