according to the ATF it is neither a shotgun or a pistol but is classified as a "firearm"
Jose - the ATF says this is neither a pistol, or a rifle, or a shotgun. It is a 'firearm', and as such, is not subject to the barrel or overall length requirements of a 'shotgun'. Check for local/state restrictions before you order, as some states/localities have passed rules against these firearms.
Jose, this is classified as a "Firearm". This essentially makes it follow the same guidelines as a handgun when it comes to purchasing. you must be 21 years of age or older to purchase.
The ATF rules that it is a "firearm", neither pistol or shotgun in this configuration. Without knowing what state you reside in I don't know if that has any consequence regarding its legality, I would probably check with the FFL you plan to use or local law enforcement.
pistol grip firearm