You might want to consider a change in scope mounts. I'm not sure what mounts you have but that would require a lot of shimming. The barrel lock up on the Century shouldn't mean there'll be an issue with breech lock up. It might be your barrel isn't straight (pointing upwards from the line of the cylinder - try it against a straight edge). Ideally you want the cross hairs to be roughly in the middle of their adjustment when zero'd.