Pump-action shotguns, also called 'slide action repeating shotguns' or 'slide action shotguns' are a class of shotguns that are distinguished in the way in which spent shells are extracted and fresh ones are chambered. The weapon has a single barrel above a tube magazine into which shells are inserted. New shells are chambered by pulling a pump handle (often called the fore-end) attached to the tube magazine toward the user, then pushing it back into place to chamber the cartridge (in a few cases this action is reversed). Fore-ends are replaceable, and modern ones may include a pistol grip for a more secure hold, picatinny rails, or a tactical light.
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 climactic extremes. Thus, until recently, military combat shotguns were almost exclusively pump-action designs.
Older pump-action shotguns are often faster than modern semi-automatic shotguns, 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 in the First World War's trench warfare.
It is popularly believed that the distinctive sound of a pump action being cycled carries an inherent deterrent effect.[1][2]
The first successful pump-action shotgun was designed by Christopher Miner Spencer, also designer of the Spencer Repeating Rifle, in 1882. The 1893 and 1897 Winchester pump-action shotguns are other early examples, the 1897 saw use in the Great War, where the Germans accused Americans of war crimes for its effectiveness.