Acombat shotgun is ashotgun issued bymilitaries forwarfare.^[1] The earliest shotguns specifically designed for combat were thetrench guns ortrench shotguns issued inWorld War I. While limited in range, the multiple projectiles typically used in ashotgun shell increase the probability of hitting a target at close quarters.^[2]

While the sporting shotgun traces its ancestry back to thefowling piece, which was a refinement of thesmoothbore musket, the combat shotgun bears more kinship to the shorterblunderbuss. Invented in the 16th century by the Dutch, the blunderbuss was used through the 18th century in warfare by the British, Austrian, Spanish (like the Escopeteros Voluntarios de Cadiz, formed in 1804, or the Compañía de Escopeteros de las Salinas, among others) and Prussian regiments, as well as in the American colonies. As use of the blunderbuss declined, the United States military began loading smaller lead shot (buckshot) in combination with their larger bullets, a combination known as "buck and ball". The buck and ball load was used extensively by Americans at theBattle of New Orleans in 1814 and was partially responsible for the disparate casualty rates between American and British forces. The advantage of this loading was that it had a greater chance of hitting the enemy, thus taking wounded soldiers out of a fight. The disadvantage of this load was that the buckshot did not cause as severe wounds at longer ranges, and contemporary accounts show many of the British wounded recovering quickly as they had been struck by the buckshot rather than the ball. Fowling pieces were commonly used by militias, for example during theTexas Revolution. However, buck and ball worked as well or better in standard or even rifled muskets. Buck and ball loads were used by both sides of theAmerican Civil War, often by cavalry units.^[2]

The development of repeatingpump-action shotguns in the 1890s led to their use by the US Marines in thePhilippines insurrections and byGeneral "Black Jack" Pershing'spursuit of Pancho Villa, and "riot" shotguns quickly gained favor with civilian police units, but the modern concept of the combat shotgun was fully developed by theAmerican Expeditionary Forces during World War I. Thetrench gun, as it was called, was a short-barreledpump action shotgun loaded with 6 rounds containingantimony-hardened00 buckshot, and equipped with a bayonet. TheM1897 andM1912 also could beslam fired: the weapon having notrigger disconnector, shells could be fired one after the other simply by working the slide if the trigger was held down, though in the heat of combat one could easily short-stroke the weapon and jam it. When fighting within a trench, the shorter shotgun could be rapidly turned and fired in both directions along the trench axis.^[3] The shotguns elicited a diplomatic protest from the German government, claiming the shotguns caused excessive injury, and that any troops found in possession of them would be subject to execution. The US Government rejected the claims, and threatened reprisals in kind if any US troops were executed for possession of a shotgun.^[2]

The shotgun was used by Allied forces and Allied-supported partisans in all theaters of combat in World War II, and both pump andsemi-automatic shotguns are currently issued to all branches of the US military; they have also been used in subsequent conflicts by French, British, Canadian, Australian, and New Zealand forces, as well as many guerrillas and insurgents throughout sub-Saharan Africa, Latin and South America, and Southeast Asia.^[2] Six different model of shotguns were accepted in the US army during World War II, the most popular being theM97 andM1912. One disadvantage of using a shotgun in the Pacific Theatre was the way of carrying the shotshells. The standard rifle pouches that carried shotshells were small, only about 30 rounds if carried vertically. Some Marines carried the shells in SL-3 grenade vests from World War I, but these vests were hard to come by. Also used were modifiedbandoliers and whatever came to hand or could be improvised.

Another disadvantage was paper-hulledshotshells, which would swell when they became damp in a rainy or humid environment, and would not fit into the chamber even after drying out. Commercial paper hulls were later impregnated with wax to make them water resistant, but in combat the heat from rapid firing would cause the wax to melt, often resulting in a jammed gun. Military-issue shotshells were usually made entirely of brass to avoid these issues, until the introduction of plastic hulls in the early 1960s.

GeneralAlexander Patch was seen armed with a Winchester shotgun when he personally led anattack in Guadalcanal.^[4]

In thejungle warfare during theMalayan Emergency, theBritish Army andlocal forces of Malaya used shotguns to great effect due to limited space in the jungles and frequent close combat. In theVietnam War, the shotgun was used as anindividual weapon in the American army during jungle patrol andurban warfare like theTet Offensive.

During theSomalian conflict in 1992, duringOperation Gothic Serpent, the US task forces tested out a new type of Remington shotgun calledCiener Ultimate Over/Under, which was an under-barrel attachment for the standardM16 variants. The idea was for a soldier in an entry team to be able to breach a locked door with the shotgun and then immediately switch to theassault rifle to clear the room. According to theArmy Rangers, their verdict was positive for this new type of breaching gun.

In operations inpost-invasion Iraq, US forces used theircombat shotguns to clear out suspectedinsurgent hideouts in house to house fighting.^[5] One notable experimental shotgun used in limited numbers duringOperation Enduring Freedom is theXM26 for breaching doors or close-quarter battle (CQB).

Combat shotguns have seen use in theRusso-Ukrainian War in the anti-drone role although their effectiveness remains unclear.^[6]

The most common type of shotgun used for this purpose is the manually operated,slide-action/pump-action type like theRemington M870 orMossberg 590A1. The latter is currently the pump-action of choice for US armed forces, and both have seen service with other militaries. The pump-action type is less prone to malfunction (particularly when dirty) thansemi-automatic designs. Pump-action shotguns are also less expensive than their semi-automatic counterparts. Even so, semi-automatic shotguns such as theBenelli M1014 are currently seeing service in NATO-aligned armed forces.

Combat shotguns typically have much shorter barrels than shotguns used for hunting. They usually have magazines of modified design to hold more than the 3 to 5 shots normal with sporting or hunting shotguns. Most combat shotguns have tubular magazines mounted underneath the barrel. These are identical to those of hunting shotguns, except for being longer to hold more ammunition. Some recent designs have detachable box magazines.

Combat shotguns are mostly similar to the policeriot shotgun. The military versions may have provisions to mount abayonet, and may be fitted with ventilated steel or plastic hand guards over the barrel to reduce the danger of a soldier burning their hand on the hot barrel during rapid fire. Riot shotguns are more likely to trade off increased magazine capacity for decreased size. For example, a combat model would be more likely to have a 51 cm (20 in) barrel and up to a 10-round capacity, while riot shotguns are often found with barrels of 35 to 46 cm (14 to 18 in) and a capacity of 5 to 8 rounds.

The combat shotgun has evolved from its original role as a short range combat weapon into a wider role in modern times. With proper configuration, ammunition and training, the modern combat shotgun plays three roles:

1. Offensive weapon
2. Breaching system
3. Less-lethalcrowd control

Effective range of the shotgun with standard buckshot is limited to about 20–30 meters. Slug rounds, if available, can extend the effective range of the shotgun to 100 meters (although this is also dependent on the shotgun's sighting system; rifle sights andghost ring sights will allow the average shooter to effectively engage human-sized targets at considerably greater distances than with a bead sight).^[7]

Less lethal rounds vary, with ranges from 10 meters for rubber buckshot to 75 meters for rubber slugs. These less lethal munitions are the same type as used by police, and have served well in riot control situations, such as that inKosovo in 2001.^[8]

When used as adoor breaching system, the shotgun may be provided with a muzzle extension to allow it to be pressed firmly against the door while providing the correct standoff distance for optimum performance. While there are specialized rounds for breaching doors with minimal hazard to any occupants of the room, any type of round will do the job, though with some degradation of effectiveness and increased risk of collateral damage. In operations in Iraq, the shotgun was the preferred method of door breaching by infantry units, ideally with a frangible breaching slug. For the breaching role, shorter barrels are preferred, as they are more easily handled in tight quarters.^[9]

Limited ammunition capacity is one of the primary downsides of the combat shotgun. While box magazines are available in some models (such as shotgun derivatives of theAK-47 design, like theSaiga-12), the tubular magazine is still dominant. This limits capacities; the current US pump shotgun issued, theMossberg 590, has a 5 or 8 shot capacity depending on barrel length. The tubular magazine does allow easy "topping off" (a tube-fed pump shotgun can be kept shouldered and aimed at a target and ready to fire while being loaded), so training emphasizes the need to load the magazine to full capacity whenever the opportunity presents itself. A common doctrine is "shoot one, load one": load a shell immediately after every shot (when this does not jeopardize the operator's safety), to ensure that the shotgun is fully loaded at all times; this ensures that the operator has a full magazine at their disposal in case of emergencies when they may not be able to reload in between shots.^[10] Apistol is also advised as a backup weapon, should the operator empty the magazine and not have time to reload. A sling to carry the shotgun is essential if it is to be used in conjunction with another weapon, so that the shotgun may be readily accessible.^[11]

The bulk and weight of shotgun ammunition also limits its utility as a general-issue weapon. Weight per 100 rounds of an average 12-gauge 00-buck2+3⁄4-inch (70 mm) shell is 4.65 kg (10.25 lb); for an average .223/5.56 round, weight per 100 rounds is about 1.22 kg (2.69 lb) or a 3.8:1 weight ratio of 12-gauge buckshot and 5.56×45mm. This means just eight 12-gauge buckshot shells weigh approximately the same (1 lb or 0.45 kg) as thirty5.56×45mm rifle cartridges. While an individual soldier can easily carry several hundred rifle or pistol cartridges in box magazines, only a few dozen shotshells can be carried practically.^{[citation needed]}

A Joint Service Combat Shotgun Program report on the lethality of shotguns in war states, in support of the use of the shotgun in warfare, "the probability of hitting a man-sized target with a shotgun was superior to that of all other weapons", and goes on to support this with statistics compiled by the British from the conflict inBorneo in the 1960s —Operation Claret.^[2]

The buckshot typically used in a combat shotgun spreads out to a greater or lesser degree depending on the barrelchoke, and can be effective at ranges as far as 70 m (77 yd). The delivery of the large number of projectiles simultaneously makes the shotgun the most effective short range weapon commonly used, with a hit probability 45% greater than a sub-machine gun (using 5-round burst), and twice as great as anassault rifle.^[2] While each pellet is only roughly as effective as a small caliberhandgun round, and offers very poor penetration against an armored target, the multiple projectiles increases the likelihood of one or more peripheral wounds.^{[citation needed]}

A number of compromises are involved in choosing a shot size:^[10][12]

• Smaller pellets lose velocity more rapidly and penetrate the target less
• Larger pellets means fewer pellets, resulting in a reduced probability of hits
• Heavier loads produce more recoil and greater velocity than lighter loads
• Reduced recoil loads (less shot and/or lower velocity) may produce smaller patterns, which may decrease hit probability

The most common type ofammunition used in combat shotguns, whether for military or law enforcement purposes, isbuckshot, typically a 70 mm (23⁄4 inch) 12-gauge shell loaded with nine hardened 00 buckshot, with a diameter of about 8.4 mm (0.33 in). Buckshot is brutally effective at close ranges against unarmored targets—enough so that Germany issued a protest against its use in 1918.^[2] The only other types of ammunition currently in use in military shotguns arebreaching rounds, which are either specially designedfrangible rounds designed to destroy a door lock or hinge while minimizing the risk of damage to occupants of the room or very light (#9) birdshot, which accomplishes the same purpose. Shotgun slugs are currently under consideration by the US military as an anti-materiel round; the tendency of typical commercial shotgun slugs to deform on impact would render them illegal under theHague Convention of 1899 and so a jacketed, hardened or sabot slug may be adopted. Less lethal rounds are used by U.S. troops serving as police forces in occupied territory; beanbag and rubber bullet rounds are commonly used to discourage looters and rioters.

In military use,flechette ammunition has also been used in shotguns (primarily byspecial forces, such as its use by theSEALs in theVietnam War),^[13] but this is not common. Other experimental shotgun ammunition has been created, such asSCMITR, but none have been successful enough to be adopted.

Due to the great flexibility of the shotgun, it is often used in non-offensive roles as well. The US Infantry, for example, offers a number ofless lethal varieties of ammunition for use in the riot control role, and for door breaching with #9 birdshot,shotgun slugs, and specialized breaching rounds. Less-lethal options also include the use of grenade launching cups, special launching cartridges and a less-lethal grenade.

There are a number of experimental rounds currently under development and consideration by the US military, including explosive rounds and stand-off breaching rounds, which could further improve the range and flexibility of the combat shotgun.

There are two primary modes of operation for combat shotguns, thepump action, and varioussemi-automatic designs, mostlygas operation andrecoil operation designs. TheSPAS-12,SPAS-15, andBenelli M3^[14] shotguns, combine the two, offering pump action or, when the pump is locked forwards, autoloading operation. There have also been a fewfully automatic shotguns produced such as theAA-12.

The autoloading shotgun (semi or fully automatic) offers a higher rate of fire than a pump shotgun, though controlling a heavyrecoiling shotgun in rapid fire is difficult. The autoloading action is more suitable for firing from a prone position, as operation of a pump action moves the elbow normally used to support the shotgun, and it can more effectively be used one-handed, unlike pump actions which require two hands for effective cycling of the action.

The pump shotgun is more versatile than the semiautomatic, as it will fire low poweredless lethal munitions which lack sufficient pressure to cycle the action in an autoloading design. A pump shotgun, which does not rely on its ammunition for energy to cycle, operates normally with the lower powered ammunition, and provides utility in combat and riot control situations. In addition, the pump shotgun has an advantage in situations such as door breaching, where the shotgun is immediately dropped (retained by a sling) and replaced by another weapon after the door has been breached. By not cycling the action after firing the final breaching rounds (multiple rounds are often required) the pump shotgun is left without a loaded round in the chamber, unlike a semiautomatic shotgun.

Due to the widespread use of the shotgun as a sporting firearm, it is used inguerrilla warfare and other forms ofasymmetric warfare.Che Guevara, in his 1961 bookGuerrilla Warfare, notes that shotgun ammunition can be obtained by guerrillas even in times of war, and that shotguns loaded with heavy shot are highly effective against unarmored troop transport vehicles. He recommends that suburban guerrilla bands should be armed with easily concealable weapons, such ashandguns and asawed-off shotgun or carbine. Guevara also mentions animprovised weapon developed by guerrillas consisting of a sawed-off 16-gauge shotgun provided with a bipod to hold the barrel at a 45-degree angle. Called the "M-16", this was loaded with ablank cartridge formed by removing the shot from a standard shotshell. A wooden rod was then placed in the barrel, with aMolotov cocktail attached to the front. This formed an improvisedmortar capable of firing the incendiary device accurately out to a range of 100 meters.^[15]

• List of combat shotguns
• List of individual weapons of the U.S. Armed Forces
• List of shotguns
• Lupara

• The World's Fighting Shotguns. Volume IV. Hardcover – 1 Jan. 1978 by Thomas F. Swearengen. Chesa Limited / T. B. N. Enterprises; First Edition (1 Jan. 1978)
• Streetsweepers: The Complete Book of Combat Shotguns Paperback – 31 Dec. 1987 by Duncan Long. Paladin Press, U.S. (31 Dec. 1987)ISBN 0873644247
• "Give Us More Shotguns!" by Bruce N. Canfield,American Rifleman, May 2004
• Bruce N. Canfield,A Collector's Guide to United States Combat Shotguns, Andrew Mowbray, 1992,ISBN 0-917218-53-1.
• Fawcett, Bill.Hunters & Shooters, An Oral History of the U.S. Navy SEALS in Vietnam. New York: Avon Books, 1995.ISBN 0-380-72166-X, pp. 79–80, especially.
• Leroy Thompson (2013).US Combat Shotguns. Weapon. Vol. 29. Osprey Publishing.ISBN 9781780960142.

• The Magnificent Mossberg,Guns & Ammo Magazine, April, 2007
• The evolution of the army combat shotgunArchived 2012-07-08 atarchive.today Military Police article by Bo Barbour
• US Army combat shotgun training video
• History of the Combat Shotgun in U.S. Army