Vulcan Guns are among the standard armaments in the Gundam series. As a type of Close-In Weapon System (CIWS), they are mostly used for point-defense and to intercept incoming missiles. The vulcan guns are usually mounted in a Mobile Suit's head, which allows it to track targets. These shell firing weapons have a high rate of fire but little power and can't damage the armor of a mobile suit, though they can damage lightly armored areas such as the sensors and can be used for intimidation. They are ideal for shooting down small, lightly armored targets such as missiles, attack vehicles, etc.
The most common model in Universal Century has caliber of 60mm. In the Cosmic Era, they are referred to as CIWS and are a common weapon found on warships and mobile suits. The name Vulcan Gun was originally coined by General Electric for their electric-powered gatling guns and being proper noun. However it has since become common slang for any electric-powered gatling gun.