A bump stock is not a machinegun

Since the National Firearms Act of 1934, federal law has heavily regulated machineguns. Indeed, as proposed, that law was known to many as “the Anti-Machine Gun Bill.” The possession or transfer of a machinegun was eventually banned through the Gun Control Act of 1968 and the Firearms Owners’ Protection Act of 1986 [with some guns grandfathered in -EV]. Today, possession of a machinegun is a federal crime, carrying a penalty of up to ten years’ incarceration.

This appeal concerns a regulation promulgated by the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives, purporting to interpret the federal prohibition on machineguns as extending to bump stocks. A bump stock is a firearm attachment that allows a shooter to harness the natural recoil of a semi-automatic weapon to quickly re-engage the trigger after firing, enabling him to shoot at an increased rate of speed. When ATF first considered the type of bump stocks at issue here, it understood that they were not machineguns. ATF maintained this position for over a decade, issuing many interpretation letters to that effect to members of the public.