Maybe some 45 GAP cases in the mix?
Heck just about every thing else has been thrown out there.. I had to scratch HARD to come up with something original.. and Possibly, maybe... er ahhh, dangifIknow possible...
A 45 firing pin will travel a ways if allowed too... Primers to shallow? nope, answered.. Broken spring... Ahh check it.. but I don't think so.. Contaminated primers? not with no marks on em... Heavy Roll Crimp... could be something there! Dirty slide interfering with pin travel, I dunno, I hope that it's not THAT dirty,, or maybe some rust or damage to the firing pin channel,,, pin a tad short? I'm just thinking out load here guys... hard to diagnose with out seeing the whole picture....
Pencil test, not a bad place to start.. run a pencil up the (EMPTY) barrel, make sure the eraser is flat and square, and eraser facing the closed breach.. (firing pin) point the pistol up, where it will cause the pencil eraser to make contact with and rest against the breach face. Lower the pistol to level, pull the trigger, see if it spits the pencil out... the distance that it throws the pencil will give you an indication of how hard the pin is hitting...
My money is on the reloads... something amiss here..