For AR 15 why so many 55 gr bullets?

[Rule3]

If the Military issue bullet is 62 or 63 grains and the black rifle craze is amongst us. My do so many load and shoot 55 gr bullets??

Because they are cheaper?

Are the 62-63 grains bullets more accurate??

All I load for the AR are bulk 55 gr projectiles. I use the more expensive Nosler, Hornady and such in bolt rifles.

For AR general range shooting what weigh bullet do you load?

 

[rcmodel]

Because the 5.56 NATO and .223 Remington were developed using 55 grain bullets, and it was the standard military bullet weight for years?

Because in my case all three of my rifles, (Early Colt carbine, early Ruger Mini-14, and CZ-527 American) all have slow twist rifling, and won't handle heavier bullets..

And it's not a bad thing.

IMO: The .223 lives and dies on high velocity.
And the old M-193 55 grain bullet in slow twist was a better close to medium range killer then what the military has saddled themselves with now.

rc

 

[4thPointOfContact]

Somewhat simplified and some parts omitted for clarity (aka, like some movies are 'based upon a true story')

Military went with the 62-grain bullet for use in the M249 SAW. The original tracer cartridge burned out before the desired range so it was lengthened. The lengthened tracer would not stabilize in the 1:9 barrel the Army had wanted for the M16A2.

Since NATO wanted to simplify ammunition distribution, it was decided that the rifle should shoot the same ammunition as the machine gun instead of having two sets of ammunition for the same platform. For this the M16A2 had the rifling rate increased to 1:7.

TL;DR version... We have 1:7 AR's because we had to be able to use the ammunition issued for the SAW and the SAW needed a long tracer to burn out to 800+ yards. The M855 was designed for the squad weapon's anti materiel role not an anti-personnel role.

It's not terrible at punching holes in people, but I wouldn't say it was optimized for it.

 

[rcmodel]

Excellent synopsis of the whole deal 4thPointOfContact!!

rc

 

[moxie]

I would only add that, in the Air Force at least, a big selling point for the whole A2/SAW M855 package was ammo commonality, including ability to use the M16's mags in the SAW.

 

[Rule3]

With a lot of rifles being 1:9 twist is there much difference in accuracy between the 55 gr and 62?. (all other things as equal as can be)

Is the 55 gr still a better choice?

 

[Surculus]

Rule3"With a lot of rifles being 1:9 twist is there much difference in accuracy between the 55 gr and 62?. (all other things as equal as can be)

Is the 55 gr still a better choice?"

No, there is not. 1in9 rifles shoot the 62gr bobos just fine. Where the rifles w/ the 1in8 & 1in7 barrels come into their own is w/ the lo-o-ong bullets used for shooting the long ranges in a match: about the longest that the 1in9 can stabilize is a 69gr, so the 72, 75, 77gr bobos with their superior ballistic coefficients [needed to carry out to the 1000yd targets & show up the competitors firing .30cal] are out of reach. But punching paper is a lot different from armed conflict.

ARs in the original 1in12 twist can't handle anything much longer than the 55gr, but shoot the original 52gr bullet quite handily. It steps right out, but loses its momentum faster due to its poor ballistic coefficient.

 

[ArchAngelCD]

My bolt action .223 rifle has a 1:12 twist and it lives on 52gr, 53gr and 55gr bullets. My 1:9 twist AR platform does just fine with the 62gr bullets although I usually shoot 55gr bullets to keep things simple.

 

[balderclev]

I've shot everything from 37gr varmint grenades to 62 gr bullets in both my rifles ar and bolt in 1-9 rifling with excellent results.

 

[joem1945]

I shoot 55 gr in my AR with a 1/12 twist. 62 gr are shot in my 1/9 twist. 69 gr are shot in my 1/7 twist. 75 gr are shot in my 1/8 twist.