Brass bolt size for crowning .30 cal

[vincyr]

OK, so I'm getting started on a project gun. Single shot .308 with a bull barrel that needs a new stock, and I'm gonna cut some weight by chopping the barrel down to 16.5". Make it a bit more handy to carry. I've seen how well a brass bolt and lapping compound can do on a recrown, so I figure I'll go that route, but I'm not sure what size bolt would work best for a .30 cal crown. Any suggestions?

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