BUMP Act

Banning Unlawful Machinegun Parts Act or the BUMP Act This bill generally prohibits the import, sale, manufacture, transfer, receipt, or possession of a device that is primarily designed, or redesigned, to increase the rate of fire when attached to a semiautomatic firearm; a device, part, or combination of parts that is designed and functions to increase the rate of fire of a firearm; or a semiautomatic firearm that has been modified to materially increase the rate of fire or to approximate the action or rate of fire of a machine gun. Additionally, the bill adds to the list of firearms subject to regulation under the National Firearms Act semiautomatic firearms that have been modified to materially increase the rate of fire or approximate the action or rate of fire of a machine gun.

Source: Congressional Research Service (CRS).