View Full Version : What's the lightest grain 223 that's accurate out of a 1 in 7 twist AR barrel?

03-15-2008, 11:11 PM
Took my AR15 (the one in my signature) with a White Oak Armament 16" stainless steel 1/7 twist barrel out to the Sunnyvale Rod and Gun club today. Just bought with me 50 rounds of Remington UMC 55 grain ammo to sight and break the gun in. It was shoot all over the place and was very inconsistent. Basically 2-3" groups at 100 yards. And I turned up the power on my Bushnell Elite 4200 6-24x40 to the max. I know.....reloading is the way to go and UMC ain't the best stuff. But that's not the concern.....was the 55 grain too light? I read that 62 grain is the lightest that one should go with in a 1/7 barrel.

Definitely going to redeem myself and the rifle and head back with some heavier grained rounds.

03-15-2008, 11:27 PM
Its not the weight causing that but the quality of the ammo. Some match 55 grainers would've probably done fine. Only problem I've had with faster twists is some varmint bullets vaporizing as soon as they leave the barrel. It happens.

03-16-2008, 12:25 AM
The quality and construction of the bullet have more to do with accuracy than the weight of the barrel.
Crappy bullets show less accuracy potential as twist rates get faster.

You can certainly shoot 55gr ammo through it and some of the 40gr bullets MAY hold together, but I sorta doubt it.
If you see a little gray cloud about 10-15 feet off your muzzle and you are not hitting anything, that's your bullets vaporizing in air from excessive twist.

03-16-2008, 1:27 AM
hrm. I shoot 55 grains just fine in my 1/7.

03-16-2008, 1:59 AM
I was key holing the 50gr UMC JHP out of my LMT 1/7, and saw some funny shrapnel marks on the target at 50 yards. But the American Eagle 55gr and m855 were spot on. I think it just depends on the individual barrel :confused: