Repro Parker Bros brass shot shells

[RickR]

A bit late in answering Josey F. about my Q on seating pistol primers, which doing it the old way with shot shells I've had 2 detonations when seating a regular primer by hand. In one instance I have a permanent scar when the brass head of a .410 separated and blew fragments into my fingers. It happened again recently when I was using the old way on a few plastic shells I cut short for some Pyrodex test loads. I was seating wads and the new primer with a wood dowel close to full 12 ga. size. The primers seemed to need a bit harder tap to get all the way in. This time, the shell rim held but the full primer force split the dowel into 4ths and my hand holding it was unhurt (whew). I am assuming the same is possible with the much softer and teeny by comparison primer (but obviously not near enough ker-bang as a shotgun primer). Any primer I might be able to seat that doesn't need more leverage than finger pressure also makes me remember the old doubles with broken firing pins that got stuck in the primer so didn't rebound and bent or broke when the gun was forced open. What am I missing?