Originally Posted by ggibson511960

Straight wall auto pistol cartridges aren't really crimped. The case neck is swaged down to remove any bell mouth added for seating. It is simply re-formed in the seating die to a uniform diameter and never crimped lest the case lose its headspace index point. Crimping is for rimmed cases. All my auto pistol dies have a generous allowance in the "crimp" section of the seating die to accommodate differing case lengths, unlike rimmed case dies that roll the case mouth and are critically dependent on uniform case length for uniform crimping. Post #6 opined about COL varying if mixed length brass is used. That's a puzzler. The seating stem has no idea how long the case is.