Milt, I have been making L.C. Smith hammer gun firing pins for years and have used 01 tool steel. This is a oil hardening tool steel and I have never hardened any of them.
Heating with a torch is not the correct way as you are hardening the steel too fast and not letting the molecules flow right. Getting the right temperature which is usually 1500F (cherry red) and then quenching it in motor oil and then cleaning the scale and polishing it then heating it again to a straw color and quenching again is difficult and without an oven I think fruitless. I have made these for many members and have had only a few break in many years.
I have just bought some S7 tool steel which is more shock resistant but have not made any pins yet. The cost is about double the price of 01. S7 is used for masonry bits and many other tools that take a lot of shock.
If you decide to harden them use Mapp gas which is a lot hotter than propane.
