The only real 'logic', if you wish to get in touch with it that, can be a shotgun does not have a rifled barrel. Causes it to be basic for your Goobermint; no rifling, it can't be a rifle. On the other hand there are actually rifled shotgun barrels or https://www.scribblemaps.com/maps/view/Hand-Crafted-Metalworks/Y7NeZjANqr