To Crimp or not to crimp?

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22to45

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That is the question...
I like Lee crimping dies, I buy in to the superstition that it makes to pressure required more even to get the bullet moving, and probably does not hurt accuracy. Of course I like the fact that the bullets never move in the case.

Has anyone done any real research to see if crimping has any effect on accuracy? I crimp them as tight as I can, and probably deform the bullet a bit doing it. Can I blame that when I miss?
 
Probably does no harm, but I don't believe it enhances accuracy at all either. For example, I have never seen a precision shooter [BR or Long Range] that crimps bullets. Additionally, if neck tension is correct, no crimp will make it any better. The only things I crimp are 357 & 44 Mag pistol, Lever action rounds that are in a tube magazine, like the 30-30, 38-55, 25-20, etc. I have loaded rifle rounds since the early 60's, and have never crimped for any except as noted. Regards, Eagleye.
 
Sorry, don't "roll" crimp your .45ACP. .45 ACP, and most other "straight walled" (they're not straight, but they're close) cases require a taper crimp.

It is not necessary to crimp rifle cases "as tight as you can". Consistent bullet pull or neck tension is what contributes to accuracy. This is obtained by using quality projectiles (all almost the same diameter) quality cases of the same lot, fired the same number of times in the same rifle, and sized sufficiently to require some seating effort.

I believe current benchrest shooters have seating force down to almost finger strength. Loads for repeating arms should have a bit more seating force, since we do not want the bullet moving back or forth, thereby changing effective case capacity. For self-loading firearms, tube fed arms, revolvers, and boomers of all discriptions, some degree of crimp is either desirable or essential. But deforming the projectile is probably not a good thing. Some folks have taken that so far that the bullets came apart in flight -most deleterious to accuracy, that - and jacket deformation probably has an unintended effect on terminal performance.
 
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