What poodleshooter said.
Also, I've ran about every type of primer available in Large Rifle, through two Lee Autoprimes (I wore one out). Some primer cups are harder (CCI) others are somewhat softer (Win, CCI BR) others relatively softer (Fed, Rem). Magnum primers are, generally speaking, somewhat harder than their Large Rifle counterparts. Then there is the sensitivity of the anvil and primer material.