I am contemplating some weld build up work on a pre 64 mod 70 bolt handle- cosmetic only. How do you reharden the camming surface after all work is completed? Thank you.

quote:

Originally posted by kda55:
I am contemplating some weld build up work on a pre 64 mod 70 bolt handle- cosmetic only. How do you reharden the camming surface after all work is completed? Thank you.

With a good heat sink, re-hardening may not be necessary at all. If cocking becomes difficult though, you can re harden by heating to a bright red (use a slightly carbon rich flame) and quenching in oil. Regards, Bill.

I do not need to do so because I use TIG welding and don't over heat them. Also, bear in mind that Model 70s are not made from case hardened mild steel, They are 4140, which already has carbon in it. So be careful.

Thank you, I will proceed slowly.

The reason for using a slightly carburizing flame is so you don't lose carbon. The same method even works on 700 bolts. You just have to localize the heat. Do not quench in water. Regards, Bill.

Thanks all I'm good to go. So much great information sharing on this site from the pros.

Heat paste and a heat sink.. heat should be as little as practical to prevent softening

It's not the process gentlemen, it's the repair should the project go south. Always have a plan B.