9mm AR barrels/upper question

[hori]

Does it make any difference whether you have a 7"/ 7.5" or 10.5"/11.5" for shooting 147gr ? Any problems with ftf/ fte or preference from RRA or CMMG complete uppers?

 

[evan the cdn]

Does it make any difference whether you have a 7"/ 7.5" or 10.5"/11.5" for shooting 147gr ? Any problems with ftf/ fte or preference from RRA or CMMG complete uppers?

Something to consider, lot's of guys are shooting 147gr bullets out of 4-6" barrels in pistols.

 

[mlehtovaara]

I think the reason he asks is because on a standard gas operated AR there is function issues with improper gas systems on shorter barrels. 9mm AR's are blowback operated so it makes no difference the length of the barrel.

If this is not the the reason he asks then it must be a question of either velocity or accuracy, in which case I don't think much changes when considering the different barrel lengths. From a 4 inch barrel to a 16 inch barrel there is only a couple hundred FPS gained.

 

[vondnik]

my 7.5 runs like a clock with whatever I feed it as long as I keep it soaked. The only "Issue" I have is with the bolt catch witch don't always work properly with my first generation plastic 10 rounds RRA mags

 

[greentips]

The whole point of shooting 147gr is to stay subsonic with a suppressor to prevent sonic crack. It really doesn't matter for us as far as I know. 9mm works on blowback - barrel length is irrelevant.

 

[hori]

ok good to know, thanks