When fitting claw mounts to existing bases, once you have got a good tight fit should the claws then be hardened, and if so, how?

Never saw it done. Would it hurt...probably not. suggest case hardening if you do it

Couldn’t hurt, I’d say if so it would be a good idea to surface harden the front mount and rear sliding lock.

I always read that if hardened they would warp. All that fitting lost. I’ve never tried it. I wonder if gas nitriding would harden them without warping.

Most I have seen are soft; if you harden them how can you file them to fit because once you solder them to the scope before fitting, then that will soften them and once you fit them, how can you harden them attached to the scope?. It's a circular problem/solution scenario.

Screw on bases are available from Recknagel. But ... this is really mostly a non issue..just leave them in he unhardened condition..They will be fine for about 100 years.

For strictly appearance. you might send them to Tunbulls..their color case is quite shallow, but the low temps they use makes very little chance of warp

Right, speaking of Turmbull; he has a CCH procedure that can color any steel, including 4140, without issue; and it does not make it brittle. I have him do Ruger Blackhawk frames. I never check the hardness.

Thanks, my thoughts were just to leave them unhardened, but wondered what the old professional gunmakers would have done.

Diamond files will cut...if you seek the trouble.

Id think if you wanted to harden them and it sounds like a good idea to prevent wear, then harden them after you finish them for goodness sakes! I suggest color case hardening for looks otherwise just case harden the notches if that can be done.