Novus,
I apply the polish, then wipe the top off. The only polish left is in the little space where the primer rounds off in the edge of the pocket. This seals the primer/case interface without leaving excess polish on the part that the firing pin strikes. I suppose that if you didn't clean your weapon, you might get some on the breech face every thousand or so rounds.
It takes a lot longer to explain it than to do it.
