Originally Posted by Carcano
Micro TIG welding. Just spoke about it with my (young) gunsmith today. Totally feasible.

Not all steel is weldable. No steel is consistently hard after being welded on. No steel can be hardened without knowing exactly what it is, or, was, because once it has been welded it is not the same anymore.

Turning a firing pin out of a material like O1, and then hardening it, is probably a better idea.

Best,
Ted