I've got at least one stock tube to start out with, and no real time deadline. The gun's on the verge of being retired from active play, and currently has an equally old Armson on it. It'd be nice, though, to be able to match bores to the paint of the day.
Wouldn't the barrel have to be double-bored, though? I'd think that the insert end would have to be bored to the OD of the inserts, and then the rest of the length would want a little relief boring to allow bigger paint to zip through it. I'd sort of forgotten that little detail.
I'm always checking my email above, if you wanted to drop me a price quote. I'd just been telling my wife that I wished I had SOME sort of project to send to you, and this might be an interesting one.