Should Mr. Polecat even consider sending a .311-312" diameter bullet down a presumably .308" bore in a rifle barrel that has thin walls and already has a ringed chamber? I realize the increased pressure probably wouldn't mean much in a stout bolt action with a thicker barrel in good condition, but this sounds questionable. Or are you suggesting that he also have the barrel rebored and rifled to the next larger bore size? I'd imagine this would be very difficult (and costly) to do with a drilling.
I'd maybe be looking at some smaller .308" diameter chamber insert for a smaller low pressure cartridge, even if it required some wild-cat creativity to form brass and reload. Of course, this likely won't be satisfactory if the goal is to use it for deer hunting. And it might involve having an exceedingly long throat which wouldn't do much for accuracy. Sometimes, it just makes more economic sense to simply retire a gun and either sell it as is, hang it above the fireplace, or part it out.
