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UMC ammo+Armalite AR10=lockup

Discussion in 'Rifle Country' started by Jason Demond, Oct 9, 2004.

  1. Jason Demond

    Jason Demond Well-Known Member

    I was shooting some UMC .308's in my Armalite AR10A2 carbine the other day. All was well, and I didn't even Know there was a problem until the last round I fired.

    Out of 100 rounds fired, six of them had the primers blow out. On the very last round, the gun failed to eject. I found a round stuck half way in the chamber.
    I had to buy a wooden dowel and pound it out. When I field stripped the rifle, I found a mangled primer.

    I would say something to Remington, if I even thought they cared.

    Why didn't you stop shooting after it happened the first time, you say.

    Well it's because I didn't catch it until I picked up my brass.

    Stay away from UMC!
  2. Zak Smith

    Zak Smith Moderator Staff Member

    Give Federal Match 168 a try. It's expensive but ought to be really accurate.

    Alternatively, I've heard good things about the Australian surplus 308.

  3. Jason Demond

    Jason Demond Well-Known Member

    Hello Zak!

    I have tried the Federal Match, and printed some of the smallest groups I have ever shot.

    As for the UMC ammo, it was a bunch I had left over from when I owned a .308 bolt gun.
  4. MaceWindu

    MaceWindu Well-Known Member

    Zak Smith?!

    Funny....my "Out dated M1A" doesn't have this problem with this ammo?! Must be the AR-10 superiority!!

  5. Jason Demond

    Jason Demond Well-Known Member

    After I got the brass cleaned up, I found the primer pockets were out of spec, not to mention the brass is soft.
    After the problems I had with this brass in my AR10, I would never try to shoot it in my M1A.
  6. Zak Smith

    Zak Smith Moderator Staff Member

    Dude, if you read that thread carefully, you'll note that not once did I state or imply that the M14/M1A was "out dated" or obsolete because of its age. Such careful reading would also reveal that I did not claim the AR-10 was superior (or the opposite). What I actually did claim, and I don't think has been argued against, is left as an exercise in reading comprehension.
  7. MaceWindu

    MaceWindu Well-Known Member

    Hey Zak...

    ...:D Just me yankin yer chain a bit...all in good fun!!!! Ar-10 is a good platform...but living in Kali, M1A is my only option....If I didnt, I would have one in the Armory!!!

    ....no offense there good buddy!!!

  8. Zak Smith

    Zak Smith Moderator Staff Member

    Fair enough.
  9. uglygun

    uglygun Well-Known Member


    I've had decent luck with UMP/Remington and have even had luck reloading it's brass.

    However, my AR10 has abso-freaking-lutely hated any Federal ammo I have fed it with it balking loudly by spitting primers into my receiver group, that goes for American Eagle, Gold Medal, and the Fed Custom ammo. And forget trying to reload that crappy brass, sure UMP is soft stuff but the Federal I have had the mispleasure of using is absolutely retardedly out of dimension after firing not even holding a primer.

    Different strokes for different folks, er ARs I suppose. I wonder if it's gone full circle and the Federal is getting a bit of quality back while the UMP is taking a dive?

    Screw it, I'll stick with Winchester or MilSurp.
  10. Southern Raider

    Southern Raider Well-Known Member

    What's probably going on is your rifle is unlocking prematurely. Some AR10s, and particularly the older one with bigger gas ports, are overgassed, which results in the carrier accelerating faster to the rear and earlier in the cycle. This can have the effect of what you are seeing (mimics a large headspace) or making the extractor work harder (dropped cases in the action, which you also saw).

    I have used an adjustable gas tube to cure some of these issues, others have added mass to the carrier.

    However, before we get to the usual AR10 brawl, you can look at this as making the rifle run with everything vs. finding the things your rifle likes.;)

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