9mm bullet seating

Discussion in 'The Ammo & Reloading Forum' started by Shooting61, Feb 14, 2010.

  1. Shooting61

    Shooting61 New Member

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    I have a 2 die set that was given to me it has no bullet seating die I was told I could use a 357 seating die is this true
  2. gdmoody

    gdmoody Moderator Supporting Member

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    It might work, I have never tried it, but I wouldn't think that it would do a proper crimp. You can buy just the bullet seater die, I think that MidwayUSA would probably have it. You could probably get it directly from the manufacturer's web site.
  3. Shooting61

    Shooting61 New Member

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    thanks for uour help do you crimp your 9mm ammo
  4. LDBennett

    LDBennett Well-Known Member

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    Crimping is completely different for rimmed cartridges cases versus rimless when used in handguns. You can NOT use the 357 seating/crimping die on 9 mm because of that.

    Semi-auto guns headspace off the front edge of the case. If that edge is roll crimped, as is done with 357 dies and any rimmed cartridge used in handguns, the cartridge will not headspace correctly, sink too deep into the chamber, and fail to fire because the firing pin will not be able to adequately reach the primer.

    Semi-auto ammo needs to be taper crimped which leaves the case front edge exposed enough to act as a limiter on the seating of the cartridge in the semi-auto gun's chamber.

    Use the correct seating die for 9 mm. Don't use the 357 seating die!

    LDBennett
  5. gdmoody

    gdmoody Moderator Supporting Member

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    I don't "crimp" the auto cases. Maybe crimp is not the proper word, I just do what ever you want to call it enough to close the bell that was created to seat the bullet.
  6. LDBennett

    LDBennett Well-Known Member

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    If you use the correct 9 mm or any other semi-auto rimless cartridge set of modern dies, the seating die includes a taper crimp. If you set the dies up per the instructions you automatically get the correct taper crimp.

    One of the big changes in pistol dies over the last 25+ years is the sizing of the cases. Today all pistol calibers are sized so that the neck tension is much higher than in earlier times. In fact, unless you can see the imprint of the base of the bullet base (most certainly on 9 mm and less so on other calibers) through the completed round's case, you are doing it wrong with old dies no longer considered adequate. The taper crimp more than just takes the bell out and adds to the case tension hold on the bullet. It has been found that neck tension holds the bullet longer so that the gas pressure can build, which leads to more uniform pressures and better accuracy. The taper crimp is part of the equation and should not be omitted.

    LDBennett
  7. Shooting61

    Shooting61 New Member

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    Thanks for the info i will find a 9mm seating die
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