AR Pistol input needed

[YFallston]

Just put the finishing touchs on my 10.5 pistol build and now I'm wondering what ammo would perform best. Ive read higher grain rounds will work better in a 1:7 twist barrel. Looking for some input from those that have built one and shot it. Thanks

 

[newq]

YFallston,

As I am sure many are going to give you much the same advice, you gotta try it out. We could have exact same rifle and no 2 are alike. You really need to source a bunch of different brands and weight and see what works for you.

 

[lee2]

62 gr works best with 1:7 twist.

 

[YFallston]

Thank. I assumed as much. I have some 55 and 62 Grs, but I read about people preferring stuff in the 70s. Just looking for feedback on what the general concenscious was.

Also, it's a radical arms 10.5 upper on an Anderson lower and I noticed a little play in the mating surfaces. Any thought on what I could try?

 

[Biggfoot44]

If you are speaking of accuracy , then yes in theory 62-69 gr bullets will give better accuraccy ( bullet length is the controling factor , not weight per se , many lead core 69gr bullets will have similar length to the millitary M885 bullet). That said go ahead and try some 55gr to see if the accuraccy is suitable for your requirements.

As far as terminal performance , the big issue is the reduced velocity from from the short bbl.

 

[ashershapiro]

55 Grain will work perfectly fine. I wouldn;t bother with the higher grain match ammo on an AR pistol. Its not like youre going super long range with it.

 

[OrbitalEllipses]

As far as terminal performance , the big issue is the reduced velocity from from the short bbl.

10.5" barrel stops making 750ft-lbs of energy necessary to consistently wound with 55gr by 35yds.

 

[Biggfoot44]

Which then leads the discussion from the tumbling and fragmenting of FMJ, to the discussion of expanding bullets.

 

[OrbitalEllipses]

Which then leads the discussion from the tumbling and fragmenting of FMJ, to the discussion of expanding bullets.

Which leads to discussion of up to 1:8 twist barrels that better stabilize heavier projectiles, though we're only talking 62-69gr soft points. Fusion Fusion MSR .223 62gr is purdy good in this regard.