New primed LC Brass, do I need to Neck size?


November 13, 2012, 01:28 PM
I just ordered 500 pieces of NEW LC 7.62x51 primed brass, do I need to size the neck? I bought some new Winchester 30/30 once and had to full length resize to get it to chamber in my model 94. I will be shooting this out of a Springfield M1A. Also should I expect to have to trim it?


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Steve Koski
November 13, 2012, 01:32 PM
Safest bet is to size, but try a few and see.

November 13, 2012, 01:40 PM
right, I know that the best bet would be to size, but I dont have a neck die for .308.....only a SB full length die, I guess I could take the decaping pin out and FL size.

November 13, 2012, 01:44 PM

The answer to your question is the following questions: Do they chamber in your M1A's chamber? Are the neck ID's small enough to hold the bullet securely? And, what is the OAL of the brass? If they fit your chamber and hold the bullet securely, then you don't need to resize them again. And if the OAL is within specs, then you don't need to trim them. Chances are with new brass you won't need to do any of this.


November 13, 2012, 01:46 PM
You can neck size with a full length die by simply raising the die and leaving about .020 between the die and shell holder when the ram is in the full up position. Do this and take the de-prime pin out. Since the casing is tapered, it won't size at all (other than the neck) until at the very end of the upstroke.

I always size all new brass. Just treat it like used brass, but if its primed you won't want to knock out the primers.

Hey, it may be just fine to load as is. Try it and see if the neck holds the bullet OK.

November 13, 2012, 02:11 PM
Thanks guys, I have not got the brass yet its on the brown M1A has not seen "new" brass in a long time. Obviously if its too long I need to trim, I was just seeing what others have had to do with this brass, its from Wideners BTW....

November 13, 2012, 06:46 PM
Personally, I always run new brass thorugh a FL die and check each case for trim too length. But if your asking if it's necessary to do so, the answer is "no" unless of course some won't chamber / extract properly. As for trimming though, I always make sure each case is as close to the same trimmed length as is possible within SAAMI spec..


November 13, 2012, 07:03 PM
You won't have to trim the new brass since it hasn't been shot or resized yet. I would suggest removing the decapping pin and running them through your die just to be sure the neck is round and has enough tension to hold the bullet securely. Or, you can resize the neck by partial sizing with the full length die which won't bump the shoulder back at all.

Note: you can only partial size this brass meant for a semi-auto because it's new virgin brass. Don't partial size any brass that's already been fired that will be fired in a semi-auto or will be used in a different bolt action rifle that originally fired in.

November 13, 2012, 07:16 PM
From what I have purchased as far as new brass I have often seen it be worse than once fired brass. Deformed necks and not full length sized correctly are the most often found problems with rifle brass for me. I use Winchester and Federal brass usually. Norma brass is always spot on BTW.

November 13, 2012, 08:28 PM
If its already primed, I wouldn't mess with it unless it won't chamber in your rifle.
Check a couple dozen pieces to be sure.

Load it, and check each round in a proper case gage if you really want to be sure it won't hang up at some inconvenient time.

A boat-tail bullet will easily expand any slightly dented case mouths.

I loaded 3000 pieces of new Remington .223 brass without doing any prep on it whatsoever. I had zero failures.


November 13, 2012, 08:35 PM
I always FL size new brass just to make sure.. just sayin'..

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