A firearm is generally a rifle, pistol, shotgun, or other portable weapon that expels a projectile (bullet) by use of an explosive action. The definition of a firearm may vary from state to state under state statutes—and under federal statutes—and related items such as a muffler or silencer may be included in the definition of a firearm for purposes of certain criminal offenses (crimes).
In California, a firearm is defined under Penal Code section 16520(a) as any device designed to be used as a weapon, from which a projectile is expelled through a barrel by the force of an explosion or other form of combustion. This broad definition includes rifles, pistols, and shotguns, among other portable weapons. California law also has specific regulations regarding the possession, sale, and transfer of firearms, including a requirement for background checks, waiting periods, and the need for a Firearm Safety Certificate. Additionally, certain items like silencers (also known as suppressors) are considered firearms in themselves and are generally illegal to possess under California Penal Code section 33410. The state's regulations are stringent and are meant to work in conjunction with federal laws, such as the Gun Control Act of 1968 and the National Firearms Act, which also regulate the ownership and transfer of firearms and related items at the federal level.