Supreme Court Decision Syllabus (scotus)

 The National Firearms Act of 1934 defines a “machinegun” as “any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.” 26 U. S. C. §5845(b). With a machinegun, a shooter can fire multiple times, or even continuously, by engaging the trigger only once. This capability distinguishes a machinegun from a semiautomatic firearm. With a semiautomatic firearm, the shooter can fire only one time by engaging the trigger. Using a technique called bump firing, shooters can fire semiautomatic firearms at rates approaching those of some machineguns. A shooter who bump fires a rifle uses the firearm’s recoil to help rapidly manipulate the trigger. Although bump firing does not require any additional equipment, a “bump stock” is an accessory designed to make the technique easier. A bump stock does not alter the basic mechanics of bump firing, and the trigger still must be released and reengaged to fire