The term swivel gun (or simply swivel) usually refers to a small cannon, mounted on a swiveling stand or fork which allows a very wide arc of movement. Another type of firearm referred to as a swivel gun was an early flintlock combination gun with two barrels that rotated along their axes to allow the shooter to switch between rifled and smoothbore barrels. Swivel guns should not be confused with pivot guns, which were far larger weapons mounted on a horizontal pivot, or screw guns, which are a mountain gun with a segmented barrel. An older term for the type is peterero (alternative spellings include "paterero" and "pederero"). The name was taken from the Spanish name for the gun, pedrero, a combination of the word piedra (stone) and the suffix -ero (-er), because stone was the first type of ammunition fired. Configuration Swivel guns are among the smallest types of cannon, typically measuring less than in length and with a bore diameter of up to . They can fire a variety of ammunition but were generally used to fire grapeshot and small caliber round shot. They were aimed through the use of a wooden handle, somewhat similar in shape to a baseball bat, attached to the breech of the weapon. Most swivel guns were muzzleloaders, but there were some breech-loading swivel guns as early as the 1410, making them among the first such examples of this type of weapon (see berços). Breech-loading swivel guns had a breech shaped like a beer mug, which the gunner would take by the handle and insert into the body of the swivel gun with the breech's opening facing forwards. The gunpowder and projectiles were loaded into the breech before it was inserted into the gun. If a number of breeches were prepared beforehand, the gunner could maintain a high rate of fire for a brief period simply by swapping out the used breech and replacing it with a freshly loaded one. Applications Swivel guns were used principally aboard sailing ships, serving as short-range anti-personnel ordnance. They were not ship-sinking weapons, due to their small caliber and short range, but could do considerable damage to anyone caught in their line of fire. They were especially useful against deck-to-deck boarders, against approaching longboats bearing boarding parties, and against deck gun crews when ships were hull-to-hull. Due to their relatively small size, swivel guns were highly portable