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I faced this issue a few years back. My seating die was adjusted to just remove the bell from the expanded case. Had no problems with chambering cartridges but I was worried about consistent ignition. I then began roll crimping my loads but noticed big differences in the crimps. A check of case lengths (measured after re-sizing) revealed significant differences. This meant that I would have to trim all my cases, which is a real pain for 38spcl and 357Mag.
I was astounded when I found that none of my cases were as long as the trim-to length specified in the reloading manuals. I even found this to be true with several batches of brand new cases in 38spcl, 357Mag, 40S&W and 45ACP. I asked advice from various sources and got different answers. Most of them involved a lot of work -- measuring, sorting and trimming.
The problem was solved when I found an article recommending taper crimpng instead of roll crimping -- no bothering with trimming to equal case length. I immediately started doing this and have never looked back. I conducted accuracy and velocity tests in my 357Mag revolvers and could tell no difference between the two crimping methods.
The only caveat I have is that the big boomers (i.e., 44Mag and up) might need heavy roll crimping. Can't say for sure since I don't reload for anything bigger than 41Mag.
270man
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