300 RUM to 7MMRUM??

Discussion in 'Reloading' started by 260shooter, Jun 23, 2005.

  1. 260shooter

    260shooter Well-Known Member

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    Oct 16, 2004
    Does the 7 RUM have the same deminsions as the 300 RUM? Could I run 300 brass through a 7 RUM die to form brass without any problems?

    Thanks

    260
     
  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Other then the neck dimension they are the same. Be careful not to exceed the neck diameter of your chamber though.

    If your rifle is a factory rifle this will "probably" not be an issue but it may be.

    Take a measure ment of the diameter of a fired case. Then compare that to the diameter of a loaded 7mm RUM using the 300 RUM brass.

    This loaded neck diameter should be at least 0.0015" less then your fired case diameter. This is minimum and I prefer a solid 0.002" smaller in diameter. This allows 0.001" neck expansion when the round is fired for the case to release the bullet.

    If the loaded round does not allow this clearance, you will get into some pressure problems depending on how tight it actually is.

    I suspect this will not be a problem if it is a factory pipe and generally, doing this results in a more quality cartridge to chamber fit as it tightens up the neck clearance.

    Good Shooting!!

    Kirby Allen(50)
     

  3. 260shooter

    260shooter Well-Known Member

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    Thanks Kirby.

    Bill