The only real 'logic', if you wish to call it that, is actually a shotgun doesn't have a rifled barrel. Causes it to be very simple for your Goobermint; no rifling, it cannot be a rifle. Even so you will find rifled shotgun barrels or slugs that should handle the https://medium.com/@handcrafted-metalworks/at-crafted-metalworks-we-do-exactly-what-our-name-says-17e170e89f56