You don't mention case length in the reloading process. "bottleneck" rifle cases grow longer with each firing, depending on the chamber they are fired in, a little or a lot. Cases that have stretched beyond maximum spec. will crumple in a die, usually the seating die. If you are reloading rifle cases, a case trimmer is a must! Neck sizing will slow the rate of stretch, but the neck sized reloads should only be fired in the same gun. (you probably already know that tidbit.)