FWIW, here is a fellow, James Calhoon, who sectioned and measured different primers and yes the cup thickness does get thicker between rifle and magnum rifle. Other factors vary as well such as hardness and tensile strength but these aren't easily measured by your average Joe (or James).
http://www.jamescalhoon.com/primers_and_pressure.phpBTW, Charlie Sisk knows more than he lets on. So I've been told.
