I was browsing through a few thread about Short barrellled shotguns and the shockwave ect. And one think that was brought up was why can a rifle be 16" and a shotgun has to be 18" and also a pistol can be from 1"--15" aka TC contender. A common as we know it terminology shotgun has a smooth bore , But what if it has a rifled bore (slug barrel) ? Is it a rifle at that point ? Is it the shells it fires(shot) ? What if it's loaded with a single projectile (slug)? Just like a rifle or pistol? It's legal to fire shot shells in rifles and handguns along with regular ammo . So what charteristic defines a shotgun legally ? In my mind a shotgun should legally be considered a rifle or pistol if it has a rifled barrel .