S. 1374 — BUMP Act

This section defines a "semiautomatic firearm" in 18 U.S.C. §921(a)(31) as a firearm that uses energy from the firing cartridge to extract the spent case, chamber the next round, and ready the firing mechanism, while requiring a separate trigger action per shot and excluding machineguns. It prohibits, effective 120 days after enactment, the import, sale, manufacture, transfer, receipt, or possession in or affecting interstate or foreign commerce of (1) manual, power-driven, or electronic attachments to semiautomatic firearms that materially increase the rate of fire or approximate a machinegun; (2) any device, part, or combination that eliminates separate trigger movements to increase rate of fire; or (3) semiautomatic firearms modified to materially increase rate of fire or approximate a machinegun (with exemptions for government entities and registered pre-enactment modifications); requires owners of lawfully possessed pre-enactment modifications under (3) to register them within 120 days under Internal Revenue Code §5841; adds the new prohibition as a violation under 18 U.S.C. §924(a)(2); and classifies such modified semiautomatic firearms as "firearms" under the National Firearms Act (26 U.S.C. §5845(a)). (Thus, the provision effectively bans bump stocks and similar rate-increasing devices and modifications, subjecting existing modified firearms to NFA regulation including taxation, marking, and recordkeeping.)