What would be a good rebore of a .308 Win in a Ruger RSI bolt action?
My first response is 358W as well, but barrels on the Ruger RSI bolt actions are very thin. I doubt there is enough meat there to bore it out to .358. If you send it to him you may want to plan to have a backup caliber in mind like a .338 Federal. Or talk it through with him first before sending the rifle to him.