Metal is exactly correct in the best way to attach this kind of bolt, (if you don't weld instead)

Remember that the only thing you need to concern yourself with on a 93, 94 95 or 96 Mauser action is the cam surface. Nothing other than the cams need to be hard on the rear of any of these Mausers. It's easy to weld or braze the new bolt on and then come back and re-harden the cam surface.

To do that you simply spot heat the area to medium red and quench in brine. Polish to bright metal and then gently heat the bolt body about 1" in front of your spot, and let the temper color run backwards until you get a straw color over the hardened area. Re-quench and re polish. Done.