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View Full Version : what grain weight for 5.56?


nickel_1022
12-02-2011, 6:31 PM
I've been using federal 55 grain with my carbine that has a 14.5 inch barrel. Any thoughts about goin to 62 grain or more? Maybe the group could tighten up a bit just due to different grain? Thanks.

nickel_1022
12-02-2011, 6:33 PM
Oops, forgot to say I'm shooting at 100yrds.
Thanks

p2rider426
12-02-2011, 6:43 PM
I've been using federal 55 grain with my carbine that has a 14.5 inch barrel. Any thoughts about goin to 62 grain or more? Maybe the group could tighten up a bit just due to different grain? Thanks.

What's the barrel twist rate? That usually plays a pretty important factor on optimum bullet weight from my understanding

bohoki
12-02-2011, 6:44 PM
i gotta say you probably wont notice any difference at that range

vintagearms
12-02-2011, 6:44 PM
with a 14.5 inch barrel, I'd go with 62gr. Thats all I shoot with mine. 14.5 with 1/7.

AeroEngi
12-02-2011, 6:54 PM
with a 14.5 inch barrel, I'd go with 62gr. Thats all I shoot with mine. 14.5 with 1/7.

Do you know of any cheap 62 grainers that aren't steel core?

roushstage3
12-02-2011, 7:09 PM
Check the twist on your barrel. You might not get the expected result out of that weight bullet.

gun toting monkeyboy
12-02-2011, 7:29 PM
I don't know if the grain weight is as much of an issue for you. What brand of ammo are you shooting? Premium loads, or bulk? Brass-cased or cheap Russian steel? Not all ammo is loaded the same. I get the bulk packed Federal at Walmart. It shoots well enough for plinking, but it is no target round. With decent hand loads I can bring the groups down from 3 inches at 100 yards to under 1 inch, using the same gun and bullet weight. I don't know if you will see much difference in terms of accuracy if you aren't using accurate loads to begin with. And milsurp/mil spec is NOT super accurate. It is designed to get reasonably close at normal ranges as cheaply as possible.

-Mb

LBDamned
12-02-2011, 8:11 PM
I'm no ballistics expert by any means - but I never pay the price for 5.56 unless it's 62 grain... If I buy 55 it's .223

I have no rhyme or reason for it that can be explained technically...

I will say however, that I seem to be more accurate/consistent with 55 grn .223 out of 1:8 twist... but psychologically I feel 62 grn 5.56 has more punch so I run that periodically (and keep a large stash of both)...

I guess I need to follow this thread and learn ~

nickel_1022
12-02-2011, 8:47 PM
Thanks guys...I believe I have a 1/7 twist. The ammo has been American eagle or federal.

nickel_1022
12-02-2011, 8:59 PM
Oh so I better say I'm getting a 2.5-3" group on average. Some days are better than others.

Ziggy91
12-02-2011, 9:03 PM
You can run pretty much anything over 55 grains in a 1:7 barrel. I haven't tried anything heavier yet in my 1:7 or 1:9, but I hope I will soon since I'm starting to shoot at distances over 100 yards. As far as a 1:7 barrel, I think you should get good results from some 75 grain match ammo. 75 or over is what 1:7 barrels are meant to handle, as long as the barrel isn't too short which I'm not sure about yours. I'm no expert btw, I've just been reading up on bullet weight recently...