While seating a CCI primer in a .44mag case, the primer detonated. The flash-bang really got my attention. I was using a 30yr old RCBS priming tool, bench mounted, and was gently applying pressure with the lever to seat the primer when it happened. I have loaded thousands of rounds of ammo and this is a first for me. My question is how much pressure to seat a primer is too much, not crushing, or is this a case of a defective primer. The primers in question are 30yrs old and have been properly stored.