Crimbing Dies

Discussion in 'The Ammo & Reloading Forum' started by jpg5324, May 2, 2012.

  1. jpg5324

    jpg5324 Member

    50
    Apr 30, 2012
    Escalon, Ca
    Will someone please explain to me the difference between tapered and roll crimp.. Will a factory crimp die work for both, or do I need two separate dies?:confused:
     
  2. gdmoody

    gdmoody Moderator Supporting Member

    Sep 7, 2007
    Athens, Georgia
    Best I can explain it is that the roll crimp appears to have the mouth of the brass slightly rolled into the seated bullet, where the taper crimp kind of pushes the mouth of the brass flat up next to the bullet. Not a great explaination but I understand what I mean.

    I use the Factory Crimp Die on all of my rifle cartridges and most of the handgun.
     

  3. Alpo

    Alpo Well-Known Member

    Feb 3, 2007
    NW Florida
    Think of a taper-crimp die like a funnel - a cone. It starts wide, and then tapers narrower. As the shell is pushed up into the die, it goes into the taper, and the case gets squished into the side of the bullet.

    This is a sketch of the inside of a rifle seating die, but a pistol die works the same, for a roll crimp.

    [​IMG]

    See the two places circled in red? Notice they are curved inward? As the case is shoved up into the die, the case-mouth hits that (it's called the "crimping shoulder") and the curve forces the case-mouth to "roll" into the bullet. That would be a "roll crimp".

    No, you can't do both from the same die. The two dies are built differently.

    Normally a revolver cartridge and a rifle cartridge die will be made with a roll crimp, while an automatic pistol cartridge die will be made with a taper crimp.
     
  4. jpg5324

    jpg5324 Member

    50
    Apr 30, 2012
    Escalon, Ca
    Cool....Now it all makes sence...I get it now.

    Thanks Guys:cool:
     
  5. JLA

    JLA Well-Known Member

    Feb 26, 2007
    Heart Of Texas
    Auto pistol cartridges will have a specific crimp spec. for instance proper crimp on a .45ACP is .470" at the case mouth +/- .001"
     
  6. steve4102

    steve4102 Former Guest

    Jan 27, 2006
    Minnesota
    You didn't specify Rifle or Pistol. The Lee Factory Crimp die for pistol is a totally different animal than a Factory Crimp Rifle die.
     
  7. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    jpg5324:

    Did you read the sticky on crimping at the top of this forum page (Reloading)?

    LDBennett
     
  8. jpg5324

    jpg5324 Member

    50
    Apr 30, 2012
    Escalon, Ca
    So, if I get the Lee Factory Crimp Die for my .357, I will get the proper roll crimp. And if I get the Lee Factory Crimp Die for my 9mm, I will get the proper taper crimp??
     
  9. jpg5324

    jpg5324 Member

    50
    Apr 30, 2012
    Escalon, Ca
    To: LDBennet
    No...But I will go back and read it now......thanks
     
    Last edited: May 3, 2012
  10. mikld

    mikld Well-Known Member

    Jun 24, 2009
    Oregon
    Prolly. .357/revolver; roll crimp. 9mm/semi-auto; taper crimp. But for me and my ammo, I have no need of the Lee FCDs for handgun ammo. I shoot lead bullets in my revolvers and a FCD swages the bullets undersize. Loaded properly, semi-auto ammo doesn't need post bullet seating resizing...
     
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