Which bullit is better for the AR?

[BrittB]

Does it matter if you shoot 55gr versus 62gr. I heard today that shooting the 55gr was bad for the AR's barrel.:confused:



Error noted, fixed I hope.

[Circuits]

There's only on "Bullitt", and that's Steve McQueen.

There will be no damage shooting either 55gr or 62gr loads, or pretty much any other load for that matter.

Heavier/longer bullets will not stabilize in old style 1/12 rifling, and really long bullets need 1/7 (military) or 1/8 (some match barrels) twists to stabilize.

40gr varmint bullets and the like will stabilize in 1/14 or faster, but may disintegrate in flight from excessive rotation in 1/8 or faster twists.

55gr will stabilize in anything 1/12 or faster.

62gr requires 1/9 or faster.

68-69gr really needs 1/8 or faster.

77gr-100 probably needs 1/7 or even faster.

Bullet length is what matters, not weight, although weight is a decent indicator of length for a given bore when talking solid lead bullets.

An unjacketed lead bullet is slightly shorter than an FMJ of the same weight, and 62gr "SS109" type bullets are partly steel, so are actually as long as a 68gr or 69gr solid lead FMJ would be.

If you made a 40gr jacketed aluminum bullet, it would be as long as a 60gr lead bullet, and would need about 1/9 to stabilize.