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Thread: Back of chamber oversize?

  1. #1
    Join Date
    Jul 2007
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    Back of chamber oversize?

    I bought a 6ppc accugauge to check and set the headspace on my 6ppc brass. The manufacturer says you can use this gauge for other calibers by using the appropriate case length gauge. I tried to do this for my 30BR brass and found that the fired brass would not go all the way into the gauge. My fired 6ppc brass goes into its gauge fine. This suggests to me that the chamber in the 30 BR barrel is oversize near the rear. Does that sound correct?

  2. #2
    Join Date
    Oct 2007
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    Connecticut
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    505
    If I am reading correctly you are using the ppc gauge with 30br brass? If that is the case then I don't think it should fit as the case head of the br .473 is larger than the ppc brass at .438. If I misinterpreted please disregard. If you bought the correct case length gauge for the br case and it didn't fit, then yes you are correct although my brass would not go back into a chamber without full length sizing if it had been fired more than twice.

  3. #3
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    Jul 2007
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    Quote Originally Posted by savet06 View Post
    If I am reading correctly you are using the ppc gauge with 30br brass? If that is the case then I don't think it should fit as the case head of the br .473 is larger than the ppc brass at .438. If I misinterpreted please disregard. If you bought the correct case length gauge for the br case and it didn't fit, then yes you are correct although my brass would not go back into a chamber without full length sizing if it had been fired more than twice.
    Yes i did use a Wilson 30BR case length gauge. The 6ppc gauge that comes with the Accugauge may have been made a little oversize as the whole purpose is to measure the case for headspace before and after sizing. All my 30BR brass is loaded right now so I'll have to wait until I shoot some to double check.

  4. #4
    Join Date
    Jul 2005
    Posts
    352
    Try rolling a case on a perfectly flat surface.

    A thicker glass plate, granite gauging plate, or even a ground cast iron surface.
    Put a light behind the case as you roll it back and forth.
    Look for changes in the light passing under the case.

    Get you eye down low enough to be looking across the flat surface.
    You can detect very small changes in shape this way.

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