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View Full Version : Bullet weight for AR-15


Mike Baugh
October 31, 1998, 06:43 PM
I picked up an AR-15 HBAR II this weekend [16" barrel] and was wondering if I should order 62gr. or 55gr. ammo , the barrel is 1/9 twist . Thanks , Mike...

Rob Pincus
October 31, 1998, 06:52 PM
If I remember right it is the 62 grns that is made for the 1/9 twist. That slower twist is supposed to work better with the heavier bullet which is supposed to be more stable, whihc defeats the whole point of the decision to use the .223 which was that in its original configuration it waslikely to tumble when it struck someone and cause some good wounds!

(is that right, or have I been living in a dream?)

fal308
November 1, 1998, 09:11 AM
Rob
You're right about the 62 gr. with the 1:9" twist.

motorep
November 1, 1998, 10:42 AM
Mike- you'll probably need to try both bullet weights to find which works for your rifle. If you're going to shoot factory loads you'll find some that work, some that are horrible. I shoot two ARs with 1/9 barrels, both are most accurate with the 55s.For factory loads Black Hills soft point will shoot better than I can, all day inside an inch. For my reloads the best is Sierra #1365 boat tail soft point - these can do 1/2 inch at 100 yds. These aren't bench rest rifles with monster scopes, these are just 3gun rifles. I hope this helps. Oh, the worst I've ever had is PMC- 4+" at 100yds.

Jeff White
November 2, 1998, 07:23 AM
Mike,
You can shoot either 55 gr or 62 gr from your 1:9 twist barrel. It is bullet length, not weight that has the greatest factor with the twist rate. When the M16A2 was being developed the 1:7 twist was required to stabilize the M856 tracer round, which is much longer then the M855 62 gr ball. The only caution I can give you is don't shoot 62 gr out of an older AR15 with a 1:12 twist. 1:12 is not fast enough to stabilize the longer 62 gr bullets. It is perfectly safe, but accuracy will be un acceptable.

Mike Baugh
November 2, 1998, 05:53 PM
Thanks guy's , Mike...

KJE
December 9, 1998, 08:00 AM
You might try using a 69gr sierra match king in the 1/9 barrel. In my 1/9 20" it is the best lod by far .68" consistently in a box stock colt flat top. 335& 748 work real well for me.