For firing pin lubrication, I think Eezox would be my choice. Synthetic so it can't deaden a primer, excellent corrosion protection, good lubricating qualities, works well at extreme temperatures.
Do a search on Eezox, and then another on the username Clayton. I learned a while back that he knows lubes, rust inhibitors, and cleaners better than I ever will. His posts on the topic are educational and useful.