i saw on youtube a guy turn a single shot shotgun into a ML. They took an empty shotgun shell and cut off all the plastic untill it was just the brass and took out the powder and watting. he just left the primer and bought a whole pack of primers. He slips the brass in, which is used as the ignition system. He then pours black powder down the barrel and then his shot. after he shoots it he just slips out the brass and replaces the primer. I dont think thats how these work though. But the guys idea for turning a shotgun into an ML seems like its perfectly legal and would pass a an ML for seasons, unless they don't allow inlines.