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Is There a Real Difference in Crimp Dies?

1002 Views 20 Replies 11 Participants Last post by  rangerhgm
Based on some discussion about the Lee FCD in another thread, I need some education please.

Can someone to explain how the dies below differ in crimping for pistol ammo. I currently use the Lee FCD (with the knob on top) and set the crimp so the line on the bullet (if pulled) is almost non-existent.
  • Lee FCD (the one with the knob on top)
  • Dillon Crimp Die
  1. Do these crimp in different ways?
  2. Does one provide better accuracy over the other?
  3. I've seen in different posts that you should have no line, or barely a line around the bullet from the crimp. Is this true no matter what crimp die you use?
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[QUOTE="9x45, post: 25007257, member: 19"]In a pistol, no. And it's not really a crimp at all, but rather a de-bell step which is just enough to take the bell off from the powder thru die. The crimp does not hold the bullet in place, it's the interference fit between the bullet OD and the case ID. Over crimping can lead to bullet setback.[/QUOTE]

As a general statement, this is not correct. It is true for some calibers, and not true for others - like .38, .357, .41 & .44 - there are probably others, but these are just one calibers I've roll crimped.

And even a taper crimp provides the interference fit to "hold" the bullet on a case that has been fired. Every try seating a bullet in a fired case that hasn't been resized or belled? It doesn't fit the same as with a taper crimp.
 
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· Scottish Member
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For semi auto cases, it is TRUE.
The above is correct, but that is not what you originally wrote.

Putting a bullet in a fired (un-sized) case makes no sense.
It given to show that sizing and the taper crimp provides the interference fit - not as a reloading practice.
 
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