Investigation of building a new rifle in an obsolete old cartridge made me wonder what kind of clearance is industry standard or typical practice between boltface and cartridge rim? For instance, if I wanted to build a 350 Rigby Magnum or 35 Newton with case head diameters of .519 and .525", respectively, how much work would be needed to alter a .532" mag bolt, if any at all? I know the extractor would probably require replacement and fitting, but would the boltface require welding and machining? I realize the practice would be different for mauser style and push feed actions like the Rem 700s.

Most rifles with H&H bolts would work with those cases.A lot of H&H cases measure down to .525
and extract ok.Ed.

Strawboss, you are going backwards. Start with an '06 bolt face & extractor and open up. Just avoid the pushfeeds, after all, a classic cartridge has no business in a pushfeed action.

Ed, John, thanks for the info. I knew you guys would know the right way to go.