Light or heavy bullets in 10" AR?


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JustinJ
October 14, 2011, 01:35 PM
I'm looking at doing a SBR AR with a barrel around 10" but am trying to decide what the ideal twist rate will be. Given the reduced length it seems that lighter bullets would be preffereable to maximize velocity akin to the 5.7 round. I'd like range out to at least 200 yards or so but CQB is primary role of said weapon.

So what are your thoughts in light vs heavier bullets from a SBR AR?

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DoubleTapDrew
October 14, 2011, 03:15 PM
IMO a 1:7 twist and a heavy bullet is better out of a short AR. The lighter bullets fragment at higher velocity (>2700fps) which you may or may not achieve out of a short barrel, and certainly won't out past 50yds or so, while the heavier ones like 75-77gr will fragment at slower velocities (~2200fps) and carry enough momentum to have decent penetration.

rjrivero
October 14, 2011, 05:29 PM
Heavy bullets. Longer dwell time. I prefer Nosler partition for SBR's as they will retain expansion velocity out to about 95-110 yards out of a 7" AR Barrel.

MenaceMan47
October 26, 2011, 01:18 AM
Good thread, I am selling my AR soon and will be starting an SBR project from scratch, as I don't need more than one AR in my collection. I will be using a 10.5" setup (all RRA), and have been curious about bullet velocities and such.

JustinJ
October 26, 2011, 10:35 AM
The only reason i've considered lighter is due to the effectiveness of the FN 5.7 round. Federal makes a 43 grain tactical round that flies albeit loses velocity fairly fast at distance.

The thing that aggravates me though is i recently discovered that with my YH Phantom Suppresser Quick Disconnect Flash hider i wont be able to remove an Adamas Arms piston without removing the flash hider. I guess I'll see what the short barrel Adcor uppers are going to go for.

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