I have an older Taurus probably built in the late 70s. I inherited it from my dad. it has had thousands of trouble free rounds through it. today i took it out and had some light primer strikes. it would go boom boom click click boom click. i ran 12 rounds through it like this. i took it inside and lightly pressed in the firing pin a few times to make sure it wasn't being held up or any thing. took it back out and the next 6 ran perfect. i looked at the primers some were off center. the ones that went off had good dents in them the ones that didn't barely had marks on them. can any one tell me whats going on and about how much it should cost. thanks in advance.