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Thread: Questions about .454 crimp

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    Member alaskamace's Avatar
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    Default Questions about .454 crimp

    Is it normal for a heavy crimp to also reduce the overall length of the cartridge? I have been loading some ammo for my .454 Casull, as well as trying to find the proper crimp needed to keep the bullet from jumping the crimp. I always seat and crimp in two steps. After crimping the round, I find that the overall length has changed anywhere from 0.01 to 0.015. I have been testing the strength of the crimp by marking one round, and leaving it in the cylinder while shooting ten to fifteen shots. I measure the overall length before and after and have found that even with this heavy crimp the bullet will still move about 0.01. This does not extend the bullet enough to bind up the cylinder. I have tested the crimp on some Hornaday factory ammo I have and had the same results. Should I be worried about this, or am I being to picky?
    ..."Tolerance is the virtue of a man without convictions." - G.K. Chesterton

  2. #2

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    I think you are overreacting a bit. Do you trim all cartridge cases before first loading or after several? The length of the cases might be slightly different. The overall case length on "straight-walled" pistol cases, especially those used in revolvers usually don't stretch much.
    But, if the cases are slightly different, when you put the heavy crimp on, it can actually pull the bullet into the case very slightly by pushing in on a tapered crimp groove in the bullet. I wouldn't fret, but I would trim the cases evenly and see what happens.

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    Quote Originally Posted by alaskamace View Post
    Is it normal for a heavy crimp to also reduce the overall length of the cartridge? I have been loading some ammo for my .454 Casull, as well as trying to find the proper crimp needed to keep the bullet from jumping the crimp. I always seat and crimp in two steps. After crimping the round, I find that the overall length has changed anywhere from 0.01 to 0.015. I have been testing the strength of the crimp by marking one round, and leaving it in the cylinder while shooting ten to fifteen shots. I measure the overall length before and after and have found that even with this heavy crimp the bullet will still move about 0.01. This does not extend the bullet enough to bind up the cylinder. I have tested the crimp on some Hornaday factory ammo I have and had the same results. Should I be worried about this, or am I being to picky?

    Yes it's normal. It depends on the width of the crimp groove. You should try to crimp the case mouth into the bottom of the groove. If you roll the case mouth into the upper part of the groove where no groove is left to be seen, the bullet will likely move forward in recoil. So when loading put the bullet where it will end up with the crimp at the bottom of the groove. Also when crimping you are rolling the case mouth in by a few thousandths and that shortens the length, in fact that is the way I measure crimp. I reduce the seated, uncrimped length by .010" up to .020" for the heaviest loads. This is with a Redding profile crimp die, I don't know if the Lee factrory crimp die would work this way.

    The 454 will handle 350 grains at about 1500 fps before it starts to slip the bullet. Your test of ten times with one round is a good test for a solid crimp.

    If it doesn' lock up the cylinder in ten shots I'd call it good.
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  4. #4
    Member alaskamace's Avatar
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    Thanks for the helpful feedback.
    ..."Tolerance is the virtue of a man without convictions." - G.K. Chesterton

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