7mm rem mag brass failure

Discussion in 'Reloading' started by HighKnob, Jun 28, 2010.

  1. HighKnob

    HighKnob Well-Known Member

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    I've been working on a load to take to wyoming this fall for antelope. This is my first experience with the 7mm rem mag reloading. I'd just picked up this 700 adl black stock gun a couple of years ago, just because it was so cheap. Anyway, my problem is I can't get 2 reloads out of Fed brass without a failure. I've shot the factory Fed round, full length resized it, shot it and now down to a bit over o.4 groups @ 100, but when i try for a 2nd reload of that brass I almost always get a failure with separation. I'm trying a couple of things, like bumping the shoulder instead of complete full length resize and trying some once fired Rem brass from another gun, full length resize. The load is on the warm side, but not max. This is the first belted mag i've owned and loaded for. I've been loading for others for 35 years i'd say and never had anything like this problem. Any ideas, it's going to antelope season before long and i'm still working, though the once fired fed brass gives a great group with 67.3 of 4350, 140 sierra gameking bt and cci 250 mag primers.
     
  2. phorwath

    phorwath Well-Known Member

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    The rifle chamber may have excessive headspace, from the bolt face to the shoulder. If you back off the resizing die to the point you're barely setting back the shoulder of the case, then you should experience good case life.

    Make sure the barrel threads are still tight in the actioin, and haven't loosened up. An excessive headspace condition is about the only thing that will cause premature case-head separation, in my experience.

    Even if the bolt to belt headspace is a bit excessive, if you headspace off the case shoulder instead of the belt, I think your problem will likely be solved.
     

  3. HighKnob

    HighKnob Well-Known Member

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    That's what i'm trying next. Thanks
     
  4. kiwi3006

    kiwi3006 Well-Known Member

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    I agree with Phorwath. I am using federal brass in my 7mm mag and have prob 5 reloads with no problems. I have set up my full length resize die so that it just pushes the shoulder back so that I can chamber the brass.
    I screwed the die down so that it touched the shell holder (with no brass) then wound it back up a few turns. Put the brass in and resized, tried to chamber brass, no go. Screw die down a bit and repeat until the brass will chamber. Seems to work.

    Stu.
     
  5. baldhunter

    baldhunter Well-Known Member

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    If your loading with IMR-4350,I'd drop down a couple of grains.I load 65.3grs of IMR-4350 and never had too much problem with case failure,in fact I've loaded some Remington cases at least a dozen times.I have heard that Federal brass is a little weak and I've only loaded a small amount of it over the years,I never really had any case failures,but it did seem to show pressure signs before the Remington brass did with the same load.I've had good luck with the Remington brass in the 7mag,you might try a few of those and see how it does.
     
  6. HighKnob

    HighKnob Well-Known Member

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    Just barely bumping the shoulders back has seemed to solve my problem. Haven't had a failure since. Thanks for the help.