How much do they cost?
The reason I ask, is I have an Adams Arms 5.45x39 upper on a NFA polymer lower. The upper came with a Wolf extra strength hammer spring, but when you shoot surplus ammo, you are bound to get a random fail to fire. Shot the gun today and had maybe 3 "clicks" out of 180 rds fired. I wonder if the titanium firing pin would provide a harder "hit" on the primer?
Every round fired after hitting it a second time.
Do you have a metal fire control group? If you don't have a metal fcg I'd start with that first.
I've got a couple fcg's in the shop if you need to buy one reasonably priced.