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Thread: Crimping Damage to Bullets

  1. #1

    Crimping Damage to Bullets

    This past weekend I pulled some 30 cal, 165 grain PPU soft points I'd loaded for fire forming trimmed and prepped brass in my 308. These loads were heavily crimped in a Lee Factory Crimp die. Needless to say, I expected to find some serious impressions on the bullets but in each case there was no mark at all. Even under magnification. Granted, the PPU 30 cal bullets are very heavily built with thick jackets (the base is .075" thick, tapering to about .030" near the nose) but I'd still expect some marking. Guess not!~Muir

  2. #2
    Well muir think its time you should maybe do a test in crimping since you started this thread. How about heavily crimping a few popular rounds and letting us no the feed back on damage . when i eventually get dies for my .243 im going to get the lee crimping die, but have read about over pressure when crimping and damaging cases ect. So would be good to here how you get on. Cheers

  3. #3
    My Lee Crimp dies work on the same principle as their collet dies so there is no 'ring' round any bullets pulled after crimping and because of the collet principle, you cannot 'over crimp' the bullet.
    Once the collet is closed it cannot go any further.
    So provided the case neck brass is all the same thickness, the crimps should all be identical.

  4. #4
    Quote Originally Posted by EMcC View Post
    My Lee Crimp dies work on the same principle as their collet dies so there is no 'ring' round any bullets pulled after crimping and because of the collet principle, you cannot 'over crimp' the bullet.
    Once the collet is closed it cannot go any further.
    So provided the case neck brass is all the same thickness, the crimps should all be identical.
    Apparently so in some cases, but how many posters voice objection to crimping on the grounds that is does damage to the bullet? ~Muir

    PS: For the record, I seldom apply a "full crimp" force from the crimp die.

  5. #5
    Quote Originally Posted by Muir View Post
    Apparently so in some cases, but how many posters voice objection to crimping on the grounds that is does damage to the bullet? ~Muir

    PS: For the record, I seldom apply a "full crimp" force from the crimp die.
    +1 - a sit on the lever crimp is rarely needed.
    More often than not a barely discernible crimp is all that is required!

  6. #6
    My take on the Lee set up was that the design prevented damage by over crimping, once the collet faces are closed no more crimping pressure can be applied?

    Unless someone else can inform us differently?

  7. #7
    Only time I see any "crimp ring" from the Lee Factory Crimp die is on plated handgun bullets which are quite soft and even then it's only a very slight indentation.

  8. #8
    Quote Originally Posted by old man View Post
    My take on the Lee set up was that the design prevented damage by over crimping, once the collet faces are closed no more crimping pressure can be applied?
    That is more eloquently put than my attempt but that is what I have found and tried to explain.
    I can remember, from a long time ago and cannot remember which dies, that some of the dies used to put and absolute 'dent' all round the bullet and it was not possible to miss seeing it if you pulled the bullet from the case.
    The modern Lee crimper is a much better 'fail safe' bit of kit, in my opinion.

  9. #9
    Unfortunately, that doesn't bear out in practice I found out. It largely depends, it seems, on the bullet jacket and the brass thickness at the neck. I got thinking about this tonight so I pulled some Midway 34 grain HP bullets that I deliberately crimped into a 22 Hornet case with max amount of leverage. The diameter of the bullet was reduced from .224" to .2205" at the crimping point. I then loaded some 150 grain Speer RN bullets into 30-30 and repeated the test. Diameter was reduced from .3075" to .304" at the crimping point. I got a similar result with a Hornady 168 grain A-Max in commercial brass. A reduction from .308" to .305". Mind you, this was a crimp that was 4X heavier than what I would normally use. Still, the "damage" was minimal. I know that the PPU bullets in military cases were totally unblemished. Hard jacket, thick brass?~Muir

  10. #10
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    Quote Originally Posted by Muir View Post
    Unfortunately, that doesn't bear out in practice I found out. It largely depends, it seems, on the bullet jacket and the brass thickness at the neck. I got thinking about this tonight so I pulled some Midway 34 grain HP bullets that I deliberately crimped into a 22 Hornet case with max amount of leverage. The diameter of the bullet was reduced from .224" to .2205" at the crimping point. I then loaded some 150 grain Speer RN bullets into 30-30 and repeated the test. Diameter was reduced from .3075" to .304" at the crimping point. I got a similar result with a Hornady 168 grain A-Max in commercial brass. A reduction from .308" to .305". Mind you, this was a crimp that was 4X heavier than what I would normally use. Still, the "damage" was minimal. I know that the PPU bullets in military cases were totally unblemished. Hard jacket, thick brass?~Muir
    Does it matter?

    Does putting a series of spiral grooves of say, .300" diameter'ish (across the rifling lands) onto a .308" bullet not just "iron out" such things as crimp marks?

    How parallel sided are bullets when they leave the barrel? ...Or... Is that not a more important consideration?

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