Source: https://www.law.cornell.edu/uscode/text/26/5845
Timestamp: 2019-04-26 15:59:01+00:00

Document:
The term “firearm” means (1) a shotgun having a barrel or barrels of less than 18 inches in length; (2) a weapon made from a shotgun if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 18 inches in length; (3) a rifle having a barrel or barrels of less than 16 inches in length; (4) a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length; (5) any other weapon, as defined in subsection (e); (6) a machinegun; (7) any silencer (as defined in section 921 of title 18, United States Code); and (8) a destructive device. The term “firearm” shall not include an antique firearm or any device (other than a machinegun or destructive device) which, although designed as a weapon, the Secretary finds by reason of the date of its manufacture, value, design, and other characteristics is primarily a collector’s item and is not likely to be used as a weapon.
The term “rifle” means a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder and designed or redesigned and made or remade to use the energy of the explosive in a fixed cartridge to fire only a single projectile through a rifled bore for each single pull of the trigger, and shall include any such weapon which may be readily restored to fire a fixed cartridge.
The term “shotgun” means a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder and designed or redesigned and made or remade to use the energy of the explosive in a fixed shotgun shell to fire through a smooth bore either a number of projectiles (ball shot) or a single projectile for each pull of the trigger, and shall include any such weapon which may be readily restored to fire a fixed shotgun shell.
The term “any other weapon” means any weapon or device capable of being concealed on the person from which a shot can be discharged through the energy of an explosive, a pistol or revolver having a barrel with a smooth bore designed or redesigned to fire a fixed shotgun shell, weapons with combination shotgun and rifle barrels 12 inches or more, less than 18 inches in length, from which only a single discharge can be made from either barrel without manual reloading, and shall include any such weapon which may be readily restored to fire. Such term shall not include a pistol or a revolver having a rifled bore, or rifled bores, or weapons designed, made, or intended to be fired from the shoulder and not capable of firing fixed ammunition.
The term “destructive device” means (1) any explosive, incendiary, or poison gas (A) bomb, (B) grenade, (C) rocket having a propellent charge of more than four ounces, (D) missile having an explosive or incendiary charge of more than one-quarter ounce, (E) mine, or (F) similar device; (2) any type of weapon by whatever name known which will, or which may be readily converted to, expel a projectile by the action of an explosive or other propellant, the barrel or barrels of which have a bore of more than one-half inch in diameter, except a shotgun or shotgun shell which the Secretary finds is generally recognized as particularly suitable for sporting purposes; and (3) any combination of parts either designed or intended for use in converting any device into a destructive device as defined in subparagraphs (1) and (2) and from which a destructive device may be readily assembled. The term “destructive device” shall not include any device which is neither designed nor redesigned for use as a weapon; any device, although originally designed for use as a weapon, which is redesigned for use as a signaling, pyrotechnic, line throwing, safety, or similar device; surplus ordnance sold, loaned, or given by the Secretary of the Army pursuant to the provisions of section 7684(2), 7685, or 7686 of title 10, United States Code; or any other device which the Secretary finds is not likely to be used as a weapon, or is an antique or is a rifle which the owner intends to use solely for sporting purposes.
The term “antique firearm” means any firearm not designed or redesigned for using rim fire or conventional center fire ignition with fixed ammunition and manufactured in or before 1898 (including any matchlock, flintlock, percussion cap, or similar type of ignition system or replica thereof, whether actually manufactured before or after the year 1898) and also any firearm using fixed ammunition manufactured in or before 1898, for which ammunition is no longer manufactured in the United States and is not readily available in the ordinary channels of commercial trade.
The term “unserviceable firearm” means a firearm which is incapable of discharging a shot by means of an explosive and incapable of being readily restored to a firing condition.
The term “make”, and the various derivatives of such word, shall include manufacturing (other than by one qualified to engage in such business under this chapter), putting together, altering, any combination of these, or otherwise producing a firearm.
The term “transfer” and the various derivatives of such word, shall include selling, assigning, pledging, leasing, loaning, giving away, or otherwise disposing of.
The term “dealer” means any person, not a manufacturer or importer, engaged in the business of selling, renting, leasing, or loaning firearms and shall include pawnbrokers who accept firearms as collateral for loans.
The term “importer” means any person who is engaged in the business of importing or bringing firearms into the United States.
The term “manufacturer” means any person who is engaged in the business of manufacturing firearms.
A prior section 5845, act Aug. 16, 1954, ch. 736, 68A Stat. 725, related to the importation of firearms into the United States or its territory, prior to the general revisions of this chapter by Pub. L. 90–618.
Provisions similar to those comprising this section were contained in prior section 5848, act Aug. 16, 1954, ch. 736, 68A Stat. 727, as amended by acts Sept. 2, 1958, Pub. L. 85–859, title II, § 203(f), 72 Stat. 1427; June 1, 1960, Pub. L. 86–478, § 3, 74 Stat. 149, prior to the general revision of this chapter by Pub. L. 90–618.
2018—Subsec. (f). Pub. L. 115–232 substituted “section 7684(2), 7685, or 7686 of title 10, United States Code” for “section 4684(2), 4685, or 4686 of title 10 of the United States Code”.
1986—Subsec. (a)(7). Pub. L. 99–308, § 109(b), substituted “any silencer (as defined in section 921 of title 18, United States Code)” for “a muffler or a silencer for any firearm whether or not such firearm is included within this definition”.
Subsec. (b). Pub. L. 99–308, § 109(a), substituted “any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun,” for “any combination of parts designed and intended for use in converting a weapon into a machinegun,”.
1976—Subsec. (a). Pub. L. 94–455, § 1906(b)(13)(A), struck out “or his delegate” after “Secretary”.
Subsec. (f). Pub. L. 94–455, § 1906(b)(13)(A), (J), struck out “or his delegate” after “shotgun or shotgun shell which the Secretary” and “of the Treasury or his delegate” after “or any other device which the Secretary”.
Amendment by Pub. L. 99–308 effective 180 days after May 19, 1986, see section 110(a) of Pub. L. 99–308, set out as a note under section 921 of Title 18, Crimes and Criminal Procedure.
Section effective on first day of first month following October 1968, except as to persons possessing firearms as defined in subsec. (a) of this section which are not registered to such persons in the National Firearms Registration and Transfer Record, see section 207 of Pub. L. 90–618, set out as a note under section 5801 of this title.

References: § 203
 § 3
 § 109
 § 109
 § 1906
 § 1906