Pump action

Source: Wikipedia, the free encyclopedia.
A Mossberg 500 12-gauge stockless pump-action shotgun with a pistol grip.
A Remington Model 760 .30-06 Springfield pump-action rifle.

Pump action is a type of manual

box magazines. Pump-action firearms are typically associated with shotguns, although it has been used in rifles, grenade launchers
, as well as other types of firearms. A firearm using this operating mechanism is colloquially referred to as a pumpgun.

Because the forend is manipulated usually with the support hand, a pump-action firearm is much 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 repeat-firing rapidly.

History

The first slide action patent was issued to Alexander Bain of Britain in 1854.[1][2] The first pump action firearm with a magazine was technically 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.[3] 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.[4]

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.[5]

Modern pump-action designs are a little slower than a

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.[6]

Disadvantages

Like most lever-action rifles and shotguns, the majority of pump-action shotguns and rifles use a fixed tubular

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.

Operating cycle

Nearly all pump-actions use a back-and-forward motion of the forend to cycle the action. Only a few pump-actions use the "reverse" or forward-and-back motion of the forend to cycle the action, a few examples are the Russian RMB-93 and South African NeoStead 2000. The forend is connected to the bolt by one or two bars; two bars are considered more reliable because it provides symmetric forces on the bolt and pump and reduces the chances of binding. The motion of the bolt back and forth in a tubular magazine model will also operate the elevator, which lifts the shells from the level of the magazine to the level of the barrel.

After firing a round, the bolt is unlocked and the forend is free to move. The shooter pulls back on the forend to begin the operating cycle. The bolt unlocks and begins to move to the rear, which extracts and ejects the empty shell from the chamber, cocks the hammer, and begins to load the new shell. In a tubular magazine design, as the bolt moves rearwards, a single shell is released from the magazine, and is pushed backwards to come to rest on the elevator.

As the forend reaches the rear and begins to move forward, the elevator lifts up the shell, lining it up with the barrel. As the bolt moves forward, the round slides into the chamber, and the final portion of the forend's travel locks the bolt into position. A pull of the trigger will fire the next round, where the cycle begins again.

Most pump-action firearms do not have any positive indication that they are out of ammunition, so it is possible to complete a cycle and have an empty chamber. The risk of running out of ammunition unexpectedly can be minimized in a tubular magazine firearm by topping off the magazine by loading new rounds to replace the rounds that have just been fired. This is especially important when hunting, as many locations have legal limits on the magazine capacity: for example, three rounds for shotguns and five rounds for rifles.

The BSA Machine Carbine used a unique pump-action that also required twisting the handguard.

Another variant was the Burgess Folding Shotgun from the late 19th century where instead of manipulating the forend to cycle the action, it had a sleeve around the grip area of the stock which the shooter would slide back and forward to cycle the gun. This was done because the forend based pump action was under patent at the time.[7]

Shotguns

The RMB-93 pump action shotgun which has the barrel below the magazine tube
Mossberg 590
pump action shotgun with the barrel over the tubular magazine.
Akkar Churchill SBS (Short Barrel Shotgun) pump action shotgun 12 inch barrel

Pump-action shotguns, also called pump shotguns, slide-action repeating shotguns or slide-action shotguns are the most commonly seen pump-action firearms. These

buttstock) for quick on-field reloading. The shells are chambered and extracted by pulling/pushing the sliding fore-end
enveloping the tubular magazine toward the user.

In modern shotguns, the fore-end can be replaceable and often include

picatinny rails or M-LOK for mounting accessories such as a tactical light, and the traditional straight grip might be replaced with a pistol grip
for a more stable control.

Trigger disconnectors

Modern pump shotgun designs, such as the

Winchester Model 12.[5]

Rifles

Colt Lightning
pump action rifle.

When used in

.44-40 caliber.[11][12] The slide action Winchester Model 1890 chambered in .22 caliber was one of the most successful repeating rimfire rifle made by Winchester. Approximately 849,000 Model 1890 rifles were produced between 1890 and 1932. Later pump-action rifles were also manufactured by Winchester, Marlin, Browning and Remington.[13]

A "reverse pump-action" design can sometimes be found, where the extraction is done by pushing the fore-end forwards, and re-chambered by pulling backwards. One such 21st-century variant is the

bolt-action rifle.[16]

Airguns

The term pump-action can also be applied to various

airgun
article for information on how spring piston and pneumatic airguns work.

Grenade launchers

The GM-94 Pump action 43mm Russian grenade launcher.

The 43mm GM-94 is a pump-action grenade launcher developed by the KBP design bureau for use by Russian special forces. It carries three rounds in an above-the-barrel tubular magazine.

Another pump-action grenade launcher is the

U.S. Navy SEALS
in the Vietnam War in limited numbers.

See also

Other long gun actions

References

  1. ISBN 0-87349-567-5
    .
  2. ^ Great Britain, Patent Office (1859). Abridgments of the Specifications Relating to Fire-arms and Other Weapons, Ammunition, and Accoutrements. London, United Kingdom: The Great Seal Patent Office. p. 169.
  3. ^ U.S. patent 54934A
  4. ^ "English Patents of Inventions, Specifications: 1866, 2187 - 2232". 1867.
  5. ^
    ISBN 978-1-5107-0924-9
    .
  6. ISBN 978-1-62636-971-9
    .
  7. ^ "Forgotten Weapons - Burgess Folding Shotgun". YouTube.
  8. ISBN 978-1-61004-693-0
    .
  9. ISBN 978-1-78096-016-6
    .
  10. ISBN 978-0-8117-0877-7
    .
  11. ISBN 0-87349-313-3
    .
  12. ISBN 978-1-59228-638-6
    .
  13. ISBN 978-1-61608-709-8
    .
  14. ^ "Test: KRIEGHOFF Semprio. An innovative first-class repeating rifle". all4shooters. 10 September 2013. Retrieved 2019-04-11.
  15. ^ Krieghoff Semprio—One Rifle, Many Possibilities[dead link]
  16. ^ "Krieghoff Semprio In-Line Action -". The Firearm Blog. 2016-05-10. Retrieved 2019-04-11.
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