I just bought a fairly nice Remington Rolling Block. It is a military rifle in 7mm Mauser. The only bad thing about the gun is that the bore looks like a sewer pipe. When I bought it, you couldn't even see the rifling. I brushed it out pretty good, even to the point of chucking my cleaning rod into my electric drill, putting a bronze bore brush on it, and giving the bore a good old roto-rooter job. At least now you can see the rifling, but it is still too rough to give any sort of accuracy. And besides, I'm not really interested in setting up to reload another caliber.
Soooooo............what I'm thinking is reboring the barrel to shoot 30-30. The only problem is that the 7mm cartridge case is a bit bigger than the 30-30. My barrel guy has solved a similar problem for me when he re-bored an old 410 single shot shotgun and converted it to 44-40. Since the 410 chamber is bigger than the 44-40, what he did was to bore a really big hole and put a chamber liner in place, and it works like a charm. The little gun is a tack driver, and since I reload 44-40 already, it's cheap to shoot.
But I'm wondering about the question of chamber pressure. The rolling block has a really thick barrel stub where it screws into the receiver, so there is plenty of room to bore a nice big hole and put a real thick chamber liner in place. But I don't want to screw things up and have the damn thing kaboom right in front of my face. The alternative is to spend $250 for a .307 barrel blank, and just have my barrel guy turn it down on the lathe to the outside dimensions of the original barrel and chamber it for the 30-30 round. But I'd just as soon (a) keep the original barrel, and (b) not spend the $250 if I don't have to.
Thoughts? Ideas?