It gets even dumber than that, as there are exceptions (and exceptions to the exception) for almost every pictured example. The top SBR Glock could be still a pistol if the rear protruding portion was just a tube to attach an approved brace design. The AOW Glock pictured below that could have a vertical attachment up front as long as that attachment held a spare magazine in it, because by definition and precedent, a spare mag holder cannot be a forward grip, even though it can serve the function of being gripped.