If you go the sleeving route, center drill the sleeve but leave it significantly undersize while you solder it in place. Some of the bearing retaining loktite would probably work as an alternative (620). Once the sleeve is in place chuck the cylinder in a 4 jaw chuck and finish drilling and reaming the chambers. That would allow you to chamber for a shell based on a modern cartridge closer to the size of the bullet you would be using. Probably wise to make the chambers a bit short so that factory shells could not be shot in the gun, only low pressure handloads
cheers mooncoon



























