Rifling Question

[Pony Express]

Hello everybody,
I have a quick question about my AR. I'm about to go pick up some ammo and I cant decide which type to get, 55 gr. FMJ or 62 gr. FMJ. It has a 1/7 twist. I always get mixed up which rifling works for which weights, is it the higher the rate of twist the lighter the bullet weight, or the opposite? Thanks, Happy shooting.

 

[Avenger29]

1/7 twist generally works better with the heavier bullets. Heavier bullets, faster twist (i.e., 1/7 is faster than 1/12). 55 grain will still shoot just fine, but won't often give the best accuracy.

 

[rcmodel]

Fast twist = heavy bullet.
Slow twist = light bullet.

rc

 

[Pony Express]

Thanks folks

 

[wishin]

Also, keep in mind that a specific rifle will fire a certain weight bullet more accurately than another with the same twist. I don't know the reason why. I tried various, and settled on the 68 gr with my target mini-14.

 

[tominct]

With me behind the stock, my Colt Match Target shoots almost as well with Malaysian ball ammo as it does with my 69 gr. Sierra MatchKing handloads. 1/7 twist. I don't know why, but at my NRA Sharpshooter ranking, I wouldn't avoid attending a match because all I had was the military stuff.

I suppose if I had an Expert or Master classification, I'd notice the difference more.

I also have a Remington Model 7 (7mm-08) that shoots well with 140 gr. factory loads, and better with handloads, but I can't get 150s to group well with any load I've tried.

Each rifle is an entity unto itself. Slow/fast/heavy/light generalizations don't necessarily apply to a particular gun.

 

[Russt]

Keep in mind the length of the bullet comes into play also. The total copper bullets are longer than a lead bullet for the same weight.