If you enjoy the forum please consider supporting it by signing up for a NES Membership The benefits pay for the membership many times over.
You don't want to butcher an all matching Mauser type by heating and bending the bolt. If anything bring the rifle and a headspace field gauge to a gun show and check out some already turned down bolts. You can often find one for cheap money, much less than what someone will charge you for heating and bending a bolt handle.