I've found the best tool for taking measurments of case head to shoulder is the Hornady Headspace set.
https://www.hornady.com/headspace-bushings#!/
With this set and a set of calipers I can measure any case and compare it to any other case, no matter if the case is loaded or not.
While I do have a dedicated depriming die, I also took a Hornady base anvil, which I put in the lathe and turned a 30thou deep pocket that will accommodate protruding primers that way it doesn't matter if I can't remove the primer.
I take this to the range and have found it very handy when others have problems.
Kiwi