Has Anyone Necksized Only For AR?


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Gun-Ther
September 8, 2008, 05:55 PM
Have you ever not full resized for your AR reloads? I know that the prevailing wisdom says to full length resize your AR brass instead of necksize only, but I wonder if it's safe to necksize only and if there'd be a gain in accuracy.

Anybody necksized only yet?

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elChupacabra!
September 8, 2008, 06:06 PM
I understand that it can be dangerous to necksize only for the AR - without bumping the shoulder back, the case (headspace length) will eventually get so long that the bolt won't be able to close properly, and if your rifle fires, it'll fire out of battery. That can be very very very bad.

I resize a very minimal amount - I bump the shoulder back about 0.003" from once-fired headspace length - to save the brass, but I think it is important to FL resize at least a tiny bit. You don't want that case growing too long on you.

rcmodel
September 8, 2008, 06:16 PM
An AR-15 cannot fire out of battery.

Unless the bolt is locked, the firing pin is held too far back by the cam in the bolt carrier to reach the primer through the bolt face.

As far as neck-sizing, I believe it is common practice for the long-range match shooters.

But they also load long bullets single-shot, and beat them in with the FA if they don't close all the way.

Still, tight and/or stuck rounds is not my idea of a fun afternoon with an AR!

rcmodel

LB7_Driver
September 8, 2008, 06:23 PM
Neck-sized-only ammo will work most of the time. Perhaps 90-95 rounds out of 100 will chamber & fire just fine.

However, having a 5%-10% failure rate due to ammunition issues is certainly not acceptable to me.

Also, there is little-to-no accuracy advantage to neck-sizing over shoulder-bumping when shooting a semi auto.

Bump the shoulder back 0.002-0.003" (as measured with the RCBS Precision Mic) and you'll still have "very accurate" ammo.
My AR reloads are capable of 1/2 MOA in my rifle.

elChupacabra!
September 8, 2008, 06:40 PM
rcmodel - that's very interesting - I did not know an AR COULDN'T fire out of battery, although now that I think about the bolt / carrier design, I suppose that does make sense... learn something new every day I suppose! :o

I guess the danger, as you say, is that it won't go into battery to begin with. Still not a good thing, as I would get very irritated by reloads that weren't reliable...

FlyinBryan
September 8, 2008, 06:41 PM
An AR-15 cannot fire out of battery.

ive wanted to say that so many times its not even funny.

i dont know why i never do, i guess cuz im really not an expert.

just basic knowledge i gained the first time i ever field stripped my 1st ar.

FlyinBryan
September 8, 2008, 06:51 PM
oh, and to the o.p.

i always full length size for everything.

as far as gaining accuracy, i cant imagine doing any better than i already am.

im f.l. sizing and saturday my groups AVERAGED 1.2 inches at one hundred yards. all 5 shot groups, and out of ten groups, two were smaller than 0.750 measured with calipers.

it is not a target rifle, its a 6lb ar15.

i would never feed out of saami spec brass through my ar. i dont see an advantage to it.

rcmodel
September 8, 2008, 06:52 PM
I did not know an AR COULDN'T fire out of battery,Well, I suppose somewhere, sometime, one has.

But unless something like the cam pin broke, or the bolt broke in half at the cam pin hole, or the firing pin broke & stuck sticking out, I must say it is very very unlikely.

But if all the parts are in place & intact, it is by design, next to impossible.

rcmodel

243winxb
September 8, 2008, 07:17 PM
Have you ever not full resized for your AR reloads? Yes, the problem i had was with the magazines. The round were slow moving up when firing on auto. No improvement in accuracy or case life from neck sizing only. An AR-15 cannot fire out of battery.
Maybe it won't fire, but i know the hammer will drop when out of battery (M16). I would not want to test it with a live round. mmmmmm maybe i will try it with a live primer. :confused:

rcmodel
September 8, 2008, 07:31 PM
Just take the bolt carrier out and look at how it works.

Unless the bolt is fully inside the carrier, rotated, and locked, the firing pin won't reach.

rcmodel

243winxb
September 8, 2008, 07:37 PM
It was had to get it to fire, but it did. The bolt was moved back about 1/8" when it went off. But i don"t think that is considered out of battery. I would think the bolt lugs are still in place. :confused: now i have to clean it, just primers firing sure makes it dirty. Taking more measurement of the bolt with the firing pin in the fire position, the bolt face has moverment of about .042" But the lugs would still be locked in. RCMODEL IS RIGHT, THEY CAN NOT FIRE OUT OF BATTERY. THE FIRING PIN DON'T REACH.

matrem
September 8, 2008, 09:27 PM
The only thing "unsafe" about it IMO,is the next round(if you're really needing it) may not fully chamber.

FM12
September 10, 2008, 09:39 AM
I tried this in ammo for a Ruger Mini 14, and had several cases stuck in the chamber. Not a pleasant afternoon! I tried it because I HATE lubing and cleaning every case. Just wanted to see...haven't tried with an AR, though. STILL hate to lube and clean!

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