California Penal Code Section 32625[1] establishes two distinct prohibitions related to machine guns. Subdivision (a) prohibits the possession or knowing transport of a machine gun within California, except as authorized by law. Subdivision (b) prohibits the intentional conversion of a firearm into a machine gun, and the sale, offer for sale, or knowing manufacture of a machine gun.
Definition of Machine Gun
Under Penal Code Section 16880,[2] a "machine gun" (spelled "machinegun" in the statute) means any weapon that shoots, is designed to shoot, or can readily be restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The definition also includes:
- The frame or receiver of any such weapon
- Any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machine gun
- Any combination of parts from which a machine gun can be assembled if those parts are in the possession or under the control of a person
- Any weapon deemed readily convertible to automatic function under ATF regulations pursuant to 26 U.S.C. Section 5801 et seq.
- Any machine gun-convertible pistol equipped with a pistol converter as defined in Penal Code Section 17015
No Civilian Exemption
Federal law under the National Firearms Act (26 U.S.C. 5801 et seq.) and the Firearm Owners Protection Act of 1986 permits civilian ownership of machine guns manufactured and registered before May 19, 1986, provided the owner pays the applicable $200 tax and completes ATF Form 4. California law provides no such exemption. Even a federally registered, tax-paid, pre-1986 machine gun is illegal to possess in California without a state-issued permit. This is one of the strictest state-level machine gun prohibitions in the country.
Limited Exemptions
The prohibition does not apply to the sale to, purchase by, or possession of machine guns by authorized law enforcement agencies and their officers, or by members of the armed forces of the United States or the National Guard when acting within the scope of their duties. Persons holding a valid DOJ-issued dangerous weapons permit under Penal Code Section 32650[3] may also possess machine guns, though such permits are rarely issued to private citizens and are generally limited to film industry prop houses and licensed manufacturers.
Penalties
PC 32625 provides different penalty structures depending on the nature of the violation:[1]
Possession or transport (subdivision (a)): Punishable by imprisonment pursuant to subdivision (h) of Section 1170, or by a fine not to exceed ten thousand dollars ($10,000), or by both a fine and imprisonment.
Intentional conversion, sale, or manufacture (subdivision (b)): Punishable by imprisonment pursuant to subdivision (h) of Section 1170 for four, six, or eight years. This is a more severe penalty than simple possession, reflecting the Legislature's determination that creating or distributing machine guns poses a greater threat to public safety than mere possession.
The distinction is significant. A person found in possession of a machine gun faces potential imprisonment and a fine, with some sentencing flexibility. A person who intentionally converts a firearm to fully automatic operation, manufactures a machine gun, or sells one faces a mandatory determinate sentence of four, six, or eight years in state prison.
Relation to Federal Law
Federal law also restricts machine guns under the National Firearms Act and 18 U.S.C. Section 922(o).[4] A person who possesses an unregistered machine gun violates both federal and state law and may be prosecuted under either or both jurisdictions. California's prohibition is broader than the federal framework because California does not recognize the pre-1986 civilian registration exception.
Bump Stocks: Federal-vs-California Divergence
On May 6, 2026, an ATF final rule, "Revising Machine Gun Definition in Response to Supreme Court Decision," took effect and removed bump stocks from the federal regulatory definition of "machine gun" in 27 CFR parts 447, 478, and 479 [5]. The rule implements Garland v. Cargill, 602 U.S. 406 (2024), in which the Supreme Court held that bump stocks are not machine guns under the National Firearms Act [6].
California state law did not change. Bump stocks remain restricted in California. The applicable state hook is not PC 32625 (which governs true machine guns as defined at PC 16880) but Penal Code Section 32900, which prohibits the manufacture, sale, possession, or use of any "multiburst trigger activator" [7]. A bump stock is a "multiburst trigger activator" under California law because it is designed to allow a semiautomatic firearm to be fired in rapid succession through manipulation of the trigger by recoil. A violation of PC 32900 is a misdemeanor.
The takeaway for California residents is that the federal rule change does not legalize bump stocks in California. Possession of a bump stock in California remains a state crime under PC 32900 even though the device is no longer regulated as a machine gun under federal law.