Pump action is a type of manual firearm action that is operated by moving a sliding handguard on the gun's forestock. After shooting a round, the sliding handguard is pulled rearward to eject the shell from an expended cartridge if present and typically to cock the hammer or striker, and then pushed forward to load a new cartridge into the chamber. Most pump-action firearms use an integral tubular magazine, although others use detachable box magazines. Pump-action mechanisms are typically found in shotguns, although they also may be found in rifles, grenade launchers, and other types of firearms. A firearm using this operating mechanism is colloquially referred to as a pumpgun. Because the forend (handguard) is usually manipulated with the support hand, a pump-action firearm can fire additional shots much faster than a bolt-action and somewhat faster than a lever-action, as it does not require the trigger hand to be removed from the trigger while reloading. Also, because the action is cycled in a linear fashion, it creates less torque that can tilt and throw the gun off aim when rapidly firing repeatedly.
History The first slide action patent, in both single-shot breech-loader and repeating magazine form, was issued to Lewis Jennings of America in 1849, although the pump was actuated via a ring trigger rather than a sliding handguard underneath the barrel. Alexander Bain of Britain patented a pump action harmonica gun in 1854 that was actuated via a sliding piece underneath the barrel. Another pump action firearm with a magazine was the gun patented in America on the 22nd of May in 1866 by Josiah V. Meigs although the pump action was actuated via the trigger guard rather than a sliding handguard underneath the barrel. The first magazine-using pump-action firearm to operate using a sliding handguard underneath the barrel was the firearm patented by William Krutzsch of Britain on the 27th of August in 1866, a few months after Meigs. The first pump-action shotgun to be sold commercially and in substantial quantities was the Spencer 1882. The first pump-action rifle, later shotgun to use a multi-lug rotating bolt was the Fosbery Pump Shotgun of 1891. Many older pump-action shotguns can be fired faster than modern ones, as they often did not have a trigger disconnector, and were capable of firing a new round as fast as the pump action was cycled, with the trigger held down continuously. This technique is called a slamfire, and was often used in conjunction with the M1897 and M1912 shotguns in World War I trench warfare. Modern pump-action designs are a little slower than a semi-automatic shotgun, but the pump-action offers greater flexibility in selection of shotshells, allowing the shooter to mix different types of loads and for using low-power or specialty loads. Semi-automatic shotguns must use some of the energy of each round fired to cycle their actions, meaning that they must be loaded with shells powerful enough to reliably cycle. The pump-action avoids this limitation. In addition, like all manual action guns, pump-action guns are inherently more reliable than semi-automatic guns under adverse conditions, such as exposure to dirt, sand, or climatic extremes. Thus, until recently, military combat shotguns were almost exclusively pump-action designs.
Disadvantages Like most lever-action rifles and shotguns, the majority of pump-action shotguns and rifles use a fixed tubular magazine. This makes for slow reloading, as the cartridges have to be inserted individually into the magazine of the firearm. However, some pump-action shotguns and rifles, including the Russian Zlatoust RB-12, Italian Valtro PM5, American Remington 7600 series, and the Mossberg 590M, use detachable box magazines.
Layout A pump-action firearm is typically fed from a tubular magazine underneath the barrel, which also serves as a guide to the movable forend. The rounds are fed in one by one through a port in the receiver, where they are pushed forward. A latch at the rear of the magazine holds the rounds in place in the magazine until they are needed. If it is desired to load the gun fully, a round may be loaded through the ejection port directly into the chamber, or cycled from the magazine, which is then topped off with another round. Pump shotguns with detachable box magazines or even drums exist, and may or may not allow the magazine to be inserted without stripping the top round.
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