300 blackout

[ragsflh]

16 inch green moutain barrel.installing gas block.best size to drill barrel for gas block.be shooting 120 gr to 150 grain bullets,non sub sonic.also pistol or carbine type gas tube

 

[hoz53]

16 inch green moutain barrel.installing gas block.best size to drill barrel for gas block.be shooting 120 gr to 150 grain bullets,non sub sonic.also pistol or carbine type gas tube

I think you would get more responses if you changed your heading a bit. Like "need help sizing ar 15 gas port" question

 

[Ggmac]

I believe .125" but I'm not at home so I'm going from memory . That's with a carbine gas tube NOT a pistol length .