A gun is a weapon that uses the force of an explosive propellant to project a missile. The rifle and the shotgun are both long-barreled weapons used for long-range shooting; the pistol has a shorter barrel and is accurate only at relatively short ranges. The revolver has a revolving barrel that allows repeat firing. The machine gun is an automatic firearm, the first of a line of weapons including assault rifles and submachine guns.
             The precise origin of these weapons is unknown, although they were known to already be in use by the early 14th century and were fairly common in Europe by mid-century. These early guns were little more than large-caliber tubes of wrought iron or cast bronze, closed at one end and loaded by placing gunpowder and projectile in the muzzle. They were fired by touching a burning wick, or match, to the powder at a "touch-hole" bored in the top of the barrel. To make sure that the powder would catch fire, a recess was incised around the hole into which additional powder was poured.
             The first major improvement in small guns was the introduction of a mechanical firing mechanism, or lock, which lowered the match to the touch hole with a pull of the trigger. The matchlock improved accuracy by permitting the gunner to concentrate on aiming the weapon, rather than having to guide the match to the primer. The principle of self-ignition was introduced in the early 16th century with the invention of the wheel-lock, which fired the powder by mechanically generated sparks. Wheel-locks were the weapon of choice for the cavalry men of the time.
             The invention of the flintlock improved on the flash-pan design. The flintlock was a spark-generating mechanism in which a flint, actuated by the trigger, struck the metal handle of the pan cover back so that the powder was exposed to receive the sparks. The flintlock was the dominant ignition system from the early 1600s. The British "Brown Bess" musket wa...