SBR build specs

[Tech]

What are you guys using for parts for your short barreled rifles? What length of barrel works best? What brand? What caliber? I'm debating between 5.56, 9mm, or 300 blackout. What is a good adjustable gas block?
Thanks!

 

[luke.reninger]

9mm I'm using a 6 inch barrel. I like 11.5 in 5.56.

Haven't messed with 300 blackout but I would do around 8.5 or 9 inches if I did build one.

I made mine short enough to suppress without being crazy long.

If your not going to suppress the 5.56, I really like 12.5 inch.

 

[Matt1911]

My 9mm AR had a 5" barrel on it.
Steve @ Cold Hand Arms has one with a 3" barrel.
My 5.56 barrel is 11.5"

 

[Wildcat]

11.5" 556
8.5" 300 BO
12.5" 6.8
4.5" 22 LR (Pistol with Sig Brace)