One minor quibble with your last post: your definitiion of case stretch. Case stretch is a permanent change in case length caused by brass flow. A good example is some .308 brass that's supposed to be 2.015 inch maximum OAL. I had some sized brass (reloaded 5-6 times) that run over length by up to 0.025 inches. What you described is the change in length caused by reducing the outside diameter of the fired case by swaging the case back to unfired diameter. The brass itself isn't stretching, it's just changing shape.