Of course they are and I'm fairly sure I know which one you are referring to. technically these are considered as MM/L's but the basic design goes back to the late 1800's. .....I have one of these new never been fired, since they are no longer sold, I wonder if it worth anything?
Yes, they are out there and I have yet to receive a reply from the OP, as to what he actually has. I think I know but without his reply, we may never know. ...A rolling block muzzle loader?