A firearm is a weapon which uses combustion to propel a projectile to a target. The word gun is sometimes synonymous with firearm, though it is sometimes used in the narrower sense of a hand-carried firearm. Firearms also include most artillery. Rocket launchers are sometimes considered firearms, and sometimes considered a separate category of weapon.
The projectile fired by a firearm can be a solid shot, multiple shots (as in a shotgun shell), or an explosive projectile.
Types of firearms
In common use, a gun is a firearm which can be carried by one person, or occasionally two.
A pistol is a small handgun designed to be held in one hand (or with both hands on the stock). The barrel of a pistol is much shorter than that of most other guns, which allows ease of carrying and concealment, but at the cost of significantly reducing accuracy at long ranges.
A rifle is a long-barrelled firearm which fires a bullet through a rifled barrel - the barrel has spiral grooves cut into the inside in order to impart spin to the bullet, to enable the bullet to fly longer before tumbling.
A machine gun is a firearm that is designed to be fired in full-automatic mode for prolonged periods of time. In other words, it will fire continuously as long as the trigger is pulled, and has both a means of providing large amounts of ammunition to the firing mechanism, and keeping the firing mechanism and other parts of the gun from overheating. While the earliest machine guns were hand-cranked, more modern weapons either use the mechanical recoil, or divert a portion of the propelling gas, to eject the fired cartridge, load a new cartridge, and fire it.