By definition, a “short-barreled shotgun” or SBS is a shotgun having one or more barrels less than 18" in length and any weapon made from a shotgun (whether by alteration, modification, or otherwise) if such weapon as modified has an overall length of less than 26". The 26" rule is important, because according to the ATF, any weapon with an overall length of less than 26" is “concealable.”

To review — an SBS is a shotgun with a barrel less than 18" and has a stock. An AoW has a shotgun receiver, a barrel less than 18", an overall length less than 26" and does not and has never had a stock. ATF rules also require you cannot possess an AoW or SBS or the parts to build one until your paperwork has been processed and you have the required tax stamp in your possession.