Commercial ammo in an m1a.

[jackdanson]

Just got a springfield m1a and was browsing the manual when I noticed a giant warning on the first few pages that stated you shouldn't use .308 ammo, only milsurp 7.62. 

What do you guys think?  Apparently the commercial .308 has sensitive primers and increases the chance of a slamfire.

This just paranoia on springfield's part or should I take this seriously?

I've got a bunch of .308, but not too much 7.62, would hate to have to buy more.

[Gewehr98]

It's a product of liability lawyers.

M1As and other M14 clones have been kaboomed with improperly assembled handloads. 

Springfield, Inc. is covering their posteriors, the receiver bridge that's supposed to capture the tail of the firing pin until the bolt's fully locked doesn't always function like it should (which begs another question), so they're pushing the milspec or hard primer angle.

Fulton Armory says the same about their AR clones.  They've received returned rifles destroyed when fired with reloads, ostensibly due to high primers, etc.  So they issue a blanket statement to cover their arses.

If you're a judicious handloader, you'll be just fine. If you're really worried, use CCI #34 primers.  You can also remember not to let the bolt fly home on a chambered round, just make certain the bolt picks up a round from the magazine each time to lessen the bolt/firing pin inertia just a smidgen.  It's the same concept behind the M1 Garand's SLED seen on match day.

If you do run commercial ammo in an M1A/M14 clone, keep the bullet weight below 175gr. and do not run Hornady "Light Magnum" rounds. 

[AJ Dual]

Just got a springfield m1a and was browsing the manual when I noticed a giant warning on the first few pages that stated you shouldn't use .308 ammo, only milsurp 7.62. 

What do you guys think?  Apparently the commercial .308 has sensitive primers and increases the chance of a slamfire.

This just paranoia on springfield's part or should I take this seriously?

I've got a bunch of .308, but not too much 7.62, would hate to have to buy more.

That'll be fun to see if they adjust the wording of that when the milsurp 7.62 is gone, which it almost is already. 

And yes, just CYA. It's an unspoken assumption you're going to get educated on just how many grains of salt with which to take their safety warnings. Which you're doing right now.

[AZRedhawk44]

I'll +1 this just to irk G98 with a +1.

 

As far as pressure differences between 7.62 NATO and commercial .308... there is a slight difference, but not enough to matter IMO.  The bigger issue to watch out for is bullet weight.  Stay away from anything outside of the 140-175 grain range.

Primers?

I have reloaded for my M1A and M14 using Winchester LRP's, CCI commercial large rifle primers (I forget the number off  the top of my head) and CCI #34's.  I have a stash of about 9K+ of #34's that I bought 2 years ago for a comparative song, so I'm committed to them for the time being.

The big issue is taking every case you reload and reaming the primer pocket to a confirmed accurate depth.  EJS makes an excellent tool for this purpose.  I do this with brand new brass that I expressly buy to handload, as well as reloaded cases from commercial or milsurp sources.  It's amazing how many primer pockets aren't to correct depth when loaded at the factory.

Before I started reaming the primer pocket, I used to just seat the primer anyways.  I could sometimes feel a high primer.  After getting several dozen cases like this that I couldn't use, I decided to get the EJS tool and add that process to my case prep.

One last thing to keep in mind:  Military 7.62 cases are slightly heavier and thicker than commercial .308.  This is to help them stand up better to machine gun use, I believe.  They hold slightly less powder, so if you commit to reloading for your rifle you will need to cut your powder charge by about 1 grain in comparison to any developed or published loads using commercial .308 brass.

[jackdanson]

DOH!!!

Took the m1a out today, was shooting some 150 gr. soft point federal.  I got through about 15 rounds and then the rifle double tapped.  I pulled the trigger once and two shots came out rapid fire.. the mag was empty at that point.  Could this have to do with the commercial ammo?  A guy at the range said his does the same thing on occasion, said it was because it "bump fires" if you don't hold the stock tight enough.  Now I'm worried...

[Gewehr98]

It's pretty difficult to accidentally bump-fire a rifle.

Remember that receiver bridge/firing pin tail thing I mentioned earlier in this thread?

You may very well have discovered one reason why Springfield, Inc. is so adament about mil-spec ammo (primers) being used in their M1A.

Glad it was just two rounds, vs. a magazine full. 

[MechAg94]

I've done it before with my M1A and my Garand.  It think it is due to milking the trigger on a bench rest.  You are trying to slowly pull the trigger back like a bolt action yet not holding it firmly enough so when it goes off, you end up rocking the trigger back and forth just enough to fire again.  I did it with surplus military ammo.

If you keep it firmly butted up to your shoulder try not to be quite so light with the trigger, it won't do it as much.  I actually try to shoot my Garands with either one round or just with the front rest only.

[HankB]

I've fired a lot of handloads using standard Winchester LR primers through my custom built M1A with no sign of a problem - I just take care to avoid high primers and use appropriate charges of powders with the correct burning rate.

I've found that IMR4064 with a 168 MKG (forget the exact charge) makes for an exceptionally accurate load.

[AZRedhawk44]

+1 MechAg.

I did this once with my M1A using south african surplus, when I first got the rifle.

Considering the OP is a new M14 shooter, I'd be more likely to ascribe this doubletap to trigger massage than to primers.

[Werewolf]

+1 MechAg.

I did this once with my M1A using south african surplus, when I first got the rifle.

Considering the OP is a new M14 shooter, I'd be more likely to ascribe this doubletap to trigger massage than to primers.

Absolutely...

I've got a book written about and for accurizing M1A's and Garands. One of the topics addressed in it is the issue of slamfires, especially in the M1A's. Slamfires are a big issue at some annual rifle competition he participates in for the Garand and M1A (DCMP???). The author claims as other posters here have that slamfires in the M1A are a function of high primers. He claims extensive testing over the years has proven the claim.

I don't imagine high primers would be a common problem with commercial ammo - would it?

[jackdanson]

Yeah, I think I double-tapped it.  I was going real light on the trigger and shooting off of a bench.  I think if it was the primers there would have been a kaboom of some type, not 2 shots going off in a burst.  I was feathering the trigger pretty lightly and it is a fairly light trigger, I think I just accidently bump-fired it.  I'm going out again tommorrow, I'll see how it goes.

[Gewehr98]

Steady pressure on the trigger, and follow through vs. stopping the pull and trying to reset it forward as soon as the gun fires.

My FN-49 and Bulgarian SLR-95 will do that doubling trick quite easily if I don't follow through on the trigger pull.

It's also a good technique for accuracy, you're not anticipating the shot, nor are you getting closer to developing a flinch.