I know many people do not bother with trimming pistol or revolver brass, but for the latter I would like to do so for my upcoming 45 Colt so that I get a uniform roll crimp. I will be using new Starline brass, like the person from a different forum I am quoting below:
I recently measured 300 new 45 Colt cases from Starline, which is excellent brass. SAAMI brass spec is 1.265" min, 1.275" trim to length, 1.285" max. I found the mean was 1.272", .003" below the trim to length, with a range of +/- .010" around the trim to length, with only 2 brass below the SAAMI min, at 1.261", and 1.263". Arranging the cases by length, the distribution looked very much like a normal curve. I trimmed to .005" below the trim to length at 1.270", but still over the SAAMI min., and tossed the cases below that. After that, no more in-process fiddling with the crimp die. Ahhh, happiness.
I've read that pistol/revolver brass shrinks over time, not grows. If this is true, I don't want to trim too much to start. I have two questions.
I recently measured 300 new 45 Colt cases from Starline, which is excellent brass. SAAMI brass spec is 1.265" min, 1.275" trim to length, 1.285" max. I found the mean was 1.272", .003" below the trim to length, with a range of +/- .010" around the trim to length, with only 2 brass below the SAAMI min, at 1.261", and 1.263". Arranging the cases by length, the distribution looked very much like a normal curve. I trimmed to .005" below the trim to length at 1.270", but still over the SAAMI min., and tossed the cases below that. After that, no more in-process fiddling with the crimp die. Ahhh, happiness.
I've read that pistol/revolver brass shrinks over time, not grows. If this is true, I don't want to trim too much to start. I have two questions.
- What is a reasonable variation in brass length that will still allow consistent roll crimps? Just for argument, let's use .005 as a talking point, then...
- Would it be reasonable in the above example to take any brass over the mean of 1.272 and trim to that length, and then discard or keep in a separate batch, anything below 1.267?
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