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 Mississippi, firearms are defined under state law in a manner consistent with the general description provided. Mississippi Code Section 97-37-1 (2020) defines a firearm as any device designed, made, or adapted to expel a projectile through a barrel by using the energy generated by an explosion or burning substance or any device readily convertible to that use. This includes rifles, shotguns, and pistols. Mississippi does not require a permit to purchase firearms and has no state-imposed waiting period or firearm registration requirements. Additionally, the state recognizes the federal definition of firearms, which includes any weapon that will or is designed to or may readily be converted to expel a projectile by the action of an explosive and the frame or receiver of any such weapon, as per the Gun Control Act of 1968. Under federal law, items such as silencers are also regulated and defined as firearms, requiring registration and a tax stamp under the National Firearms Act. It's important to note that both state and federal laws are subject to change, and individuals should consult an attorney for the most current legal advice regarding firearms.