Since the 45 ACP headspaces on the case mouth, two things are critical: The length of the case and the type and amount of crimp you use. This being said, I have never purchased any new brass or factory ammo that was too short or too long, and with the straight wall, have reloaded until the cases were no longer reloadable before there was enough elongation. Remember, except in a 45 ACP revolver with half moon clips, the case mouth is up against the end of the chamber at the time of firing.
If you are concerned, take a look at the SAMMI diagram of the case in one of your loading manuals and put a set of calipers on a few cases. If you are seeing increased length for some reason, than a trim die might be in your future, but my case trimmers have never seen a pistol case.
Last edited by rkittine
on Wed Feb 07, 2018 8:27 am, edited 1 time in total.
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