I had a Black Diamond a while back. You can put any scope on it that you would normally put on a centerfire. It doesn't have to be a "muzzleloader/shotgun" scope. You should be prepared to get that scope and rings messy with fouling from the open breech area on the Black Diamond. That was the main reason I traded mine off, I didn't like getting an expensive scope charred everytime I went to the range. But on a sidenote, the BD was a very good shooting rifle if you don't mind the mess it makes!