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Thread: Another case trimming question

  1. #1
    Member Daveintheburbs's Avatar
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    Apr 2003
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    Eagle River, AK
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    Default Another case trimming question


    When I buy new bulk brass I give them a quick neck resize to round the case mouth then trim to min length. This way I start with a known length. Occasionally I will trim slightly smaller that min trim length by accident. When this happens I throw the offending case away. I always figured that there was a min length for a reason.

    My question is: have I been unnecessarily pitching good brass for no real reason? What do other folks do in this situation?
    Thanks
    Dave

  2. #2
    Moderator
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    Jan 2005
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    Default Pitchin' in..

    Dave,

    Yes, just pitch it my way.

    There actually is no minimum length except for those that headspace on the case mouth (45 ACP, 40 S&W, 9X19, etc.). The trim length for bottle neck rifle is just to reduce it's length to .010" below maximum to allow the case to "grow" during firings without exceeding maximum length. Maximum length is given as such because high pressures could result in a case being too long, not the case being too short.

    If you trim one case a few thousands too short, you can trim them all to that length for better uniformity in bullet tension. That is a factor in accuracy and consistant velocity. Generally rifle cartridges that head space on the rim, belt or shoulder will not be adversely affected by being a few thousands too short, unless you're a bench rest shooter.

    I work new brass the same way you do, neck size to get correct tension and round out the mouth. Then I trim all to the same (hopefully) length by setting the trimmer up on the shortest case then trimming just enough to get rid of the jagged mouth so typical on new Winchester, Remington or Federal brass. Actually Lapua is the only one I don't need to trim. I don't really care how long it is now as long as it is at least .005" shorter than maximum overall length..
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



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