The only real 'logic', if you wish to get in touch with it that, is often a shotgun doesn't have a rifled barrel. Causes it to be uncomplicated with the Goobermint; no rifling, it cannot be a rifle. Having said that you will find rifled shotgun barrels or slugs that https://www.cylex.us.com/company/hand-crafted-metalworks-38956581.html