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View Full Version : Springfield M1A - 308 vs 7.62 ammo


Lunker
October 14, 2009, 09:49 AM
Can someone straighten me out on this? I am interested in getting a nice long range rifle in 308. I have a Colt Match Target already, so I wasn't looking to go the AR route. I had my sights set on a Springfield M1A. I have since read about possible problems with using commercial 308ammo. Something about the primers being too soft. Is it true that I would only be able to use miltary 7.62 ammo (with the harder primers) in the rifle?

TriumphGuy
October 14, 2009, 09:53 AM
I doubt it. If that were the case, it would be pretty tough to reload for the M1A and I know several people who do.

azredhawk44
October 14, 2009, 10:09 AM
Something about the primers being too soft. Is it true that I would only be able to use miltary 7.62 ammo (with the harder primers) in the rifle?

Two issues here:

#1: Soft primers or other commercial ammo concerns.

Don't worry about the primer in any retail commercial cartridge. Lots of guys shoot Federal match ammo from their M1A's, and Federal is widely regarded as having the softest, touchiest primers on the market. Ammo makers recess the primer far enough that the M1A floating firing pin won't set it off.

The other concerns are powder type and bullet weight. They tend to go hand in hand. Too slow of a powder burn rate and you get too much pressure at the gas port, which gives too much force to the op rod. This can bend or break it, resulting in gunsmithing fees and possible injury to the shooter. Too heavy of a bullet can cause the same thing.

Best bet for M1A's? Shoot 150gr, 165gr and 168gr ammo from the rifle. Stay away from anything 180gr or heavier.

Soft point or other hunting ammo? Not a problem. Take the file from a multitool and softly round the leading edge of the magazine. I've found that softpoints have a tendency to snag the lead tip of the bullet against the rough leading edge of a mag. Filing this to a smooth radius eliminates the problem.

#2: 7.62x51 NATO versus .308 Winchester.

http://www.fulton-armory.com/308.htm

I trust anything that Fulton Armory has to say on the issue.

Basically...

If your rifle headspaces longer than normal (1.635" or longer) you should use only 7.62 NATO ammo and brass. The brass is thicker and stronger than commercial brass.

If your rifle headspaces between 1.631 and 1.635, it should be okay to use commercial .308 brass.

Reason? 7.62 NATO was designed largely for automatic fire and machine guns tend to have really long headspace in comparison to precision marskmanship rifles. So, they leave the chambers sloppy for easier feed and extraction, and beef up the brass strength.

I'm willing to bet a new Springer today will headspace right around 1.634.