machinegun

A machinegun is an automatic firearm, defined in 26 U.S.C. § 5845(b) as a weapon that automatically shoots, is designed to automatically shoot, or can be readily restored to shoot more than one shot automatically, without reloading manually, and with one single function of the trigger. The statutory definition also includes the frame or receiver of such a weapon, as well as certain parts, and combinations of parts that are designed and intended for use in converting another weapon into a machinegun, or from which a machinegun may be assembled.

In Garland v. Cargill, 602 U.S. 406 (2024), the U.S. Supreme Court held that a semiautomatic rifle equipped with a bump stock does not qualify as a “machinegun” under § 5845(b). The Court reasoned that the rifle does not fire more than one shot by a single function of the trigger because the shooter must release and re-engage the trigger between shots. By contrast, the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) has determined that an auto sear (colloquially referred to as a switch), can constitute a machinegun under § 5845(b) because the part is designed and intended for use in converting a weapon into a machinegun. See: ATF Ruling 81-4. The Hughes Amendment (18 U.S.C. § 922(o)), generally prohibits the possession or transfer of machineguns, subject to statutory exceptions. One exception permits the lawful transfer or possession of a machinegun that was lawfully possessed prior to May 19, 1986.

[Last reviewed in August of 2026 by the Wex Definitions Team]

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