There was a comment on roll crimp earlier in this thread, regarding trim length and consistent crimp.
Minor variation in case length, then the comment made is a fine comment.
So that someone still on beginning end of the learning curve doesn't misunderstand it though: if the brass is not trimmed uniformly, and you use a roll crimp, it is possible to buckle case walls if the cases are of inconsistent length. This is very possible, even in brass used is from same lot of factory ammunition shot in one gun. The trimming has to be to a fairly consistent length or simple buckling is a potential.
Post #59 is helpful to me, because there is (using Willbird's phrase-ology) a 5th choice to his fourth...
It is uncommon, but sometimes helpful on cases using heavy bullets and no powder compression, to put a constriction or crimp at the Base of the bullet to provide another obstruction to bullet setback during recoil. I guess I would call it a base crimp.
If I remember right, I have also see ammunition for applications like this where there was a crimp at the case mouth and a crimp ring part way down the neck into the captured bullet body. It looks like it may be possible using a clever adaptation of a LEE FCD to do that.
On these types of cases w/ heavy bullets and heavy recoil, I also remember seeing a crimp type (I think a stab crimp, or bayonet crimp, it was called) where there is a strong indentation pressed into the case neck thus creating a point of intrusion of the case neck into the seated bullet. I think it was 3 points around the neck at the same distance from mouth. I suppose the number could vary.
Me, I don't want a crimp like this stab crimp really ever, but I have wanted a base crimp a couple times, or a mid-body bullet crimp, and I believe my initial thoughts on tinkering w/ a LEE FCD may work based on post #59. So, thanks for the idea confirmation, before I went to tinkering on my own.
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Originally Posted by Soundguy
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