Neck Split in AR15


John Galt
September 21, 2003, 08:56 PM

I just loaded 1000 rounds for my 223 bolt gun and shot lots of prairie dogs this weekend. All went well. My brass was once fired military and once fired Remington.

I used the same load, 26.6 grn Varget and 50grn vMax for my friend. His brass was supposed to be "once fired" and was also Remington-Peters. Same press and load, etc. Neck sized, no crimp, body die set to "touch" back any really long brass.

- He had quite a few splits from the rim of neck to the shoulder.

* Is this brass not as advertised, ie very used?
* Does the AR do this often, is it the rifle?
* Did my failing to push back fully with the body die cause the problem through the rifle not fully chambering long shouldered brass. ie just a speck over SAAMI max.


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Nero Steptoe
September 21, 2003, 10:21 PM
Well, you don't neck size for an AR, like you would for your bolt gun. You'd do well to use a f.l. sizing die and set it up using a case gauge, such as the Wilson case gauge for adjusting the sizing die to properly bump the shoulder for correct headspace.

September 22, 2003, 12:36 PM
Was the military brass splitting, or the Remington? Military brass is often fired in rather generous machinegun chambers which could lead to excessive stretching, even with one firing.

September 23, 2003, 09:39 AM
I second doing full length resizing for the AR. Neck Sizing only is okay for bolt action and single shots, but not self-loaders.

September 23, 2003, 05:05 PM
Don't you guys anneal with brittle brass?


John Galt
September 23, 2003, 05:17 PM
As this was a hurry job, I never checked the chamber length or neck size.
My neck die isn't real tight, but may have been the problem.
Luckilly, it was a one time deal and my friend returned the AR and will be buying a bolt gun. He was impressed with the accuracy of mine.

I got an email back from the brass seller and he assures me it's once fired from police range, which is what I was after.

Since it was only once fired from 223, I didn't think it necessary to anneal.

Thanks guys.

Nero Steptoe
September 23, 2003, 10:10 PM
What's so difficult about this? You don't neck size for an AR! Has nothing to do with how "loose" your die is!

If your friend had been properly introduced to an AR, he probably would have been equally impressed with its accuracy!

September 26, 2003, 09:14 AM
Nero is right! Neck sizing is for bolt actions and it doesn't work well in ALL bolt actions. NEVER neck size for autoloaders. The tolerance will be much too tight and ruin brass besides the possibility of an accident.
It would be very unusual for once-fired-brass to split in the neck.


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