The period repair was to half sole the frizzen to provide a new surface. The original frizzens I have seen where the case had been worn through, were worn unevenly and really did need a half sole, not just re-case hardening to put them back in service. I would use 1095 for the half sole. All that said, I would be reluctant to do it to an original frizzen. That is significantly changing the character and history of the frizzen and the gun. That is not something you generally want to do to original guns. After all, you shouldn't be shooting an original flintlock. Just my two cents.
