Originally Posted by
Lead pot
CPA uses a chamber that is not the normal, but close what seems to be standard.
This is my thought on his problem. .481" case mouth .020" brass thickness gives the fired case inside diameter .461" not allowing for some spring back as the case cools. If that case is trimmed as fired tight to the chamber end and snug fit in the case before it is fired it is possible that the case neck gets pulled up in the transition and gets swaged down to less then the diameter of the bullet.
I have this problem when my cases start to lengthen and need to be trimmed with the tight chambers I use.
:) just a little more loading controversy :)