Thread: Timney Trigger Causing Light Primer Strikes

I'd check headspace on dud cartridges, a small piece of lead against the back of cartridge (not against the primer!) and close the bolt on it, micrometer that.

A few fractions of mm difference in firing pin travel will not make a significant difference to primer indentation. Primer cups are super WEAK relative to the (factory) spring forces on a firing pin. What stops the firing pin is the firing pin shoulder, not how hard or soft the primer cup is. That's why you can dry fire a rifle without worry: primers don't buffer firing pins.