Shotgun

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A shotgun (also known as a scattergun, peppergun,^[1] or historically as a fowling piece) is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which discharges numerous small spherical projectiles called shot, or a single solid projectile called a slug. Shotguns are most commonly used as smoothbore firearms, meaning that their gun barrels have no rifling on the inner wall, but rifled barrels for shooting sabot slugs (slug barrels) are also available.

Shotguns come in a wide variety of calibers and gauges ranging from 5.5 mm (.22 inch) to up to 5 cm (2.0 in), though the 12-gauge (18.53 mm or 0.729 in) and 20-gauge (15.63 mm or 0.615 in) bores are by far the most common. Almost all are breechloading, and can be single barreled, double barreled, or in the form of a combination gun. Like rifles, shotguns also come in a range of different action types, both single-shot and repeating. For non-repeating designs, over-and-under and side-by-side break action shotguns are by far the most common variants. Although revolving shotguns do exist, most modern repeating shotguns are either pump action or semi automatic, and also fully automatic, lever-action, or bolt-action to a lesser extent.

Preceding smoothbore firearms (such as the musket) were widely used by European militaries from the 17th until the mid-19th century.^[2] The muzzleloading blunderbuss, the direct ancestor of the shotgun, was also used in similar roles from self-defense to riot control. Shotguns were often favored by cavalry troops in the early to mid-19th century because of its ease of use and generally good effectiveness on the move, as well as by coachmen for its substantial power. But by the late 19th century, these weapons became largely replaced on the battlefield by breechloading rifled firearms shooting spin-stabilized cylindro-conoidal bullets, which were far more accurate with longer effective ranges. The military value of shotguns was rediscovered in the First World War, when American forces used the pump-action Winchester Model 1897 shotgun in trench fighting to great effect. Since then, shotguns have been used in a variety of close quarters combat roles in civilian, law enforcement, and military applications.

The smoothbore shotgun barrel generates less resistance and thus allows greater propellant loads for heavier projectiles without as much risk of overpressure or a squib load, and are also easier to clean. The shot pellets from a shotshell are propelled indirectly through a wadding inside the shell and scatter upon leaving the barrel, which is usually choked at the muzzle end to control the projectile scatter. This means each shotgun discharge will produce a cluster of impact points instead of a single point of impact like other firearms. Having multiple projectiles also means the muzzle energy is divided among the pellets, leaving each individual projectile with less penetrative kinetic energy. The lack of spin stabilization and the generally suboptimal aerodynamic shape of the shot pellets also make them less accurate and decelerate quite quickly in flight due to drag, giving shotguns short effective ranges. In a hunting context, this makes shotguns useful primarily for hunting fast-flying birds and other agile small/medium-sized game without risking overpenetration and stray shots to distant bystander and objects. However, in a military or law enforcement context, the high short-range blunt knockback force and large number of projectiles makes the shotgun useful as a door breaching tool, a crowd control or close-quarters defensive weapon. Militants or insurgents may use shotguns in asymmetric engagements, as shotguns are commonly owned civilian weapons in many countries. Shotguns are also used for target-shooting sports such as skeet, trap, and sporting clays, which involve flying clay disks, known as "clay pigeons", thrown in various ways by a dedicated launching device called a "trap".

Design factors[edit]

Action[edit]

The action is the operating mechanism of a gun. There are many types of shotguns, typically categorized by the number of barrels or the way the gun is reloaded.

Break-action[edit]

For most of the history of the shotgun, the breechloading break-action shotgun was the most common type, and double-barreled variants are by far the most commonly seen in modern days. These are typically divided into two subtypes: the traditional "side-by-side" shotgun features two barrels mounted horizontally beside each other (as the name suggests), whereas the "over-and-under" shotgun has the two barrels mounted vertically one on top of the other. Side-by-side shotguns were traditionally used for hunting and other sporting pursuits (early long-barreled side-by-side shotguns were known as "fowling pieces" for their use hunting ducks and other waterbirds as well as some landfowls), whereas over-and-under shotguns are more commonly associated with recreational use (such as clay pigeon shooting). Both types of double-barrel shotgun are used for hunting and sporting use, with the individual configuration largely being a matter of personal preference.

Another, less commonly encountered type of break-action shotgun is the combination gun, which is an over-and-under design with one smoothbore barrel and one rifle barrel (more often with a rifle barrel on top, but a rifle barrel on bottom was not uncommon). There is also a class of break-action guns called drillings, which contain three barrels, usually two smoothbore barrels of the same gauge and a rifled barrel, though the only common theme is that at least one barrel be smoothbore. The most common arrangement was essentially a side-by-side shotgun with the rifled barrel below and centered. Usually a drilling containing more than one rifled barrel would have both rifled barrels in the same caliber, but examples do exist with different caliber barrels, usually a .22 long rifle and a centerfire cartridge. Although very rare, drillings with three and even four (a vierling) shotgun barrels were made.

Pump-action[edit]

In pump-action shotguns, a linearly sliding fore-end handguard (i.e. pump) is manually moved back-and-forth like a hand pump to work the action, extracting the spent shell and inserting a new round, while cocking the hammer or striker. A pump-action shotgun is typically fed from a tubular magazine underneath the barrel, which also serves as a guide rail for the pump. The rounds are fed in one by one through a port in the receiver, where they are lifted by a lever called the elevator and pushed forward into the chamber by the bolt. A pair of latches at the rear of the magazine hold the rounds in place and facilitate feeding of one shell at a time. 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. Well-known examples include the Winchester Model 1897, Remington 870, and Mossberg 500/590.

Pump-action shotguns are common hunting, fowling and sporting shotguns. Hunting models generally have a barrel between 600 and 700 mm (24"-28"). Tube-fed models designed for hunting often come with a dowel rod or other stop that is inserted into the magazine and reduces the capacity of the gun to three shells (two in the magazine and one chambered) as is mandated by U.S. federal law when hunting migratory birds. They can also easily be used with an empty magazine as a single-shot weapon, by simply dropping the next round to be fired into the open ejection port after the spent round is ejected. For this reason, pump-actions are commonly used to teach novice shooters under supervision, as the trainer can load each round more quickly than with a break-action, while unlike a break-action the student can maintain his grip on the gun and concentrate on proper handling and firing of the weapon.

Pump-action shotguns with shorter barrels and little or no barrel choke are highly popular for use in home defense, military and law enforcement, and are commonly known as riot guns. The minimum barrel length for shotguns in most of the U.S. is 18 inches (460 mm), and this barrel length (sometimes 18.5–20 in (470–510 mm) to increase magazine capacity and/or ensure the gun is legal regardless of measuring differences^[3]) is the primary choice for riot shotguns. The shorter barrel makes the weapon easier to maneuver around corners and in tight spaces, though slightly longer barrels are sometimes used outdoors for a tighter spread pattern or increased accuracy of slug projectiles. Home-defense and law enforcement shotguns are usually chambered for 12-gauge shells, providing maximum shot power and the use of a variety of projectiles such as buckshot, rubber, sandbag and slug shells, but 20-gauge (common in bird-hunting shotguns) or .410 (common in youth-size shotguns) are also available in defense-type shotgun models allowing easier use by novice shooters.

A riot shotgun has many advantages over a handgun or rifle. Compared to "defense-caliber" handguns (chambered for 9mm Parabellum, .38 Special, .357 Magnum, .40 S&W, .45 ACP and similar), a shotgun has far more power and damage potential (up to 10 times the muzzle energy of a .45 ACP cartridge), allowing a "one-shot stop" that is more difficult to achieve with typical handgun loads. Compared to a rifle, riot shotguns are easier to maneuver due to the shorter barrel, still provide better damage potential at indoor distances (generally 3–5 meters/yards), and reduce the risk of "overpenetration"; that is, the bullet or shot passing completely through the target and continuing beyond, which poses a risk to those behind the target through walls. The wide spread of the shot reduces the importance of shot placement compared to a single projectile, which increases the effectiveness of "point shooting" – rapidly aiming simply by pointing the weapon in the direction of the target. This allows easy, fast use by novices.

Lever-action[edit]

Early attempts at repeating shotguns invariably centred around either bolt-or lever-action designs, drawing inspiration from contemporary repeating rifles, with the earliest successful repeating shotgun being the lever-action Winchester M1887, designed by John Browning at the behest of the Winchester Repeating Arms Company.

Lever shotguns, while less common, were popular in the late 19th century with the Winchester Model 1887 and Model 1901 being prime examples. Initially very popular, demand waned after the introduction of pump-action shotguns around the start of the 20th century, and production was eventually discontinued in 1920.

One major issue with lever-actions (and to a lesser extent pump-actions) was that early shotgun shells were often made of paper or similar fragile materials (modern hulls are plastic or metal). As a result, the loading of shells, or working of the action of the shotgun, could often result in cartridges getting crushed and becoming unusable, or even damaging the gun.

Lever shotguns have seen a return to the gun market in recent years, however, with Winchester producing the Model 9410 (chambering the .410 gauge shotgun shell and using the action of the Winchester Model 94 series lever-action rifle, hence the name), and a handful of other firearm manufacturers (primarily Norinco of China and ADI Ltd. of Australia) producing versions of the Winchester Model 1887/1901 designed for modern 12-gauge smokeless shotshells with more durable plastic casings. There has been a notable uptick in lever-action shotgun sales in Australia since 1997, when pump-actions were effectively outlawed.

Bolt-action[edit]

Bolt-action shotguns, while uncommon, do exist. One of the best-known examples is a 12-gauge manufactured by Mossberg featuring a 3-round magazine, marketed in Australia just after changes to the gun laws in 1997 heavily restricted the ownership and use of pump-action and semi-automatic shotguns. They were not a huge success, as they were somewhat slow and awkward to operate, and the rate of fire was noticeably slower (on average) than a double-barrelled gun. The Rifle Factory Ishapore in India also manufactured a single-shot .410 bore shotgun based on the SMLE Mk III* rifle. The Russian Berdana shotgun was effectively a single-shot bolt-action rifle that became obsolete, and was subsequently modified to chamber 16-gauge shotgun shells for civilian sale. The U.S. military M26 is also a bolt-action weapon. Bolt-action shotguns have also been used in the "goose gun" application, intended to kill birds such as geese at greater range. Typically, goose guns have long barrels (up to 36 inches), and small bolt-fed magazines. Bolt-action shotguns are also used in conjunction with slug shells for the maximum possible accuracy from a shotgun.^[4]

In Australia, some straight-pull bolt-action shotguns, such as the Turkish-made Pardus BA12 and Dickinson T1000, the American C-More Competition M26, as well as the indigenous-designed SHS STP 12, have become increasingly popular alternatives to lever-action shotguns, largely due to the better ergonomics with less stress on the shooter's trigger hand and fingers when cycling the action.

Revolver[edit]

Colt briefly manufactured several revolving shotguns that were met with mixed success. The Colt Model 1839 Shotgun was manufactured between 1839 and 1841. Later, the Colt Model 1855 Shotgun, based on the Model 1855 revolving rifle, was manufactured between 1860 and 1863. Because of their low production numbers and age they are among the rarest of all Colt firearms.^[5]

The Armsel Striker was a modern take on the revolving shotgun that held 10 rounds of 12-gauge ammunition in its cylinder. It was copied by Cobray as the Streetsweeper.^[6][7]

Taurus manufactures a carbine variant of the Taurus Judge revolver along with its Australian partner company, Rossi known as the Taurus/Rossi Circuit Judge. It comes in the original combination chambering of .410 bore and .45 Long Colt, as well as the .44 Remington Magnum chambering. The rifle has small blast shields attached to the cylinder to protect the shooter from hot gases escaping between the cylinder and barrel.^[8]

The MTs255 (Russian: МЦ255) is a shotgun fed by a 5-round internal revolving cylinder. It is produced by the TsKIB SOO, Central Design and Research Bureau of Sporting and Hunting Arms. They are available in 12, 20, 28 and 32 gauges, and .410 bore.

Semi-automatic[edit]

Recoil/inertia-driven or gas-operated actions are other popular methods of increasing the rate of fire of a shotgun; these self-loading shotguns are generally referred to as autoloaders. Instead of having the action manually operated by a pump or lever, the action automatically cycles each time the shotgun is fired, ejecting the spent shell and reloading a fresh one into the chamber. The first successful semi-automatic shotgun was John Browning's Auto-5, first produced by Fabrique Nationale beginning in 1902. Other well-known examples include the Remington 1100, Benelli M1, and Saiga-12.

Some, such as the Franchi SPAS-12 and Benelli M3, are capable of switching between semi-automatic and pump action. These are popular for two reasons; first, some jurisdictions forbid the use of semi-automatic actions for hunting, and second, lower-powered rounds, like "reduced-recoil" buckshot shells and many less-lethal cartridges, have insufficient power to reliably cycle a semi-automatic shotgun.

Automatic[edit]

Fully automatic shotguns, such as the 1960's (appeared in 1967) Vietnam War era Remington Model 7188 (designed for and used by US Navy SEALs in Vietnam), the Auto Assault-12 (AA-12) or the USAS-12 also exist, but they are still rare.

Other[edit]

In addition to the commonly encountered shotgun actions already listed, there are also shotguns based on the Martini-Henry rifle design, originally designed by British arms maker W.W. Greener.

Some of the more interesting advances in shotgun technology include the versatile NeoStead 2000 and fully automatics such as the Pancor Jackhammer or Auto-Assault 12.

In 1925, Rodolfo Cosmi produced the first working prototype hybrid semi-automatic shotgun, which had an 8-round magazine located in the stock. While it reloaded automatically after each shot like a semi-automatic, it had a break-action to load the first shell. This design has only been repeated once, by Beretta with their UGB25 automatic shotgun. The user loads the first shell by breaking the gun in the manner of a break-action shotgun, then closes it and inserts the second shell into a clip on the gun's right side. The spent hulls are ejected downwards. The guns combine the advantages of the break action (they can be proven to be safe by breaking open, there are no flying hulls) with those of the semi-automatic (low recoil, low barrel axis position hence low muzzle flip).

The Italian firearms manufacturer Benelli Armi SpA also makes the Benelli M3, a dual-mode hybrid shotgun that allows the user the choice of semi-automatic or pump-action operation. Pump-action operation is employed when shooting less energetic shells (such as baton rounds) that do not generate enough recoil to operate the semi-automatic mechanism. Conversely, the semi-automatic mode can be employed with more powerful shells, absorbing some of the recoil. Switching between the two modes is done by manipulating the ring located at the front of the foregrip.

The French firearm manufacturer Verney-Carron produces the Véloce shotgun, a "lever-release blowback firearm" using bolt catch mechanism like its similarly designed SpeedLine rifle. The Véloce is in essence a modified inertia-driven semi-automatic shotgun, but after blowback the bolt is trapped by a bolt stop and cannot return to battery unless it is manually released by depressing a thumb lever near the tang of the grip. Because the gun will not chamber a new round without manual actuation, the design is technically not really a self-loading, and Verney-Carron described it as a "manual repeating shotgun". When Australian firearm dealers tried to import the Véloce shotgun in 2018, Greens' David Shoebridge and anti-gun groups such as Gun Control Australia caused a moral panic on the mainstream media, calling it "semi-semi-automatic" that needed to be prohibited as a "rapid-fire weapon".^{[9][10][11][12]}

Gauge[edit]

The gauge number is determined by the weight, in fractions of a pound, of a solid sphere of lead with a diameter equal to the inside diameter of the barrel. So, a 10-gauge shotgun nominally should have an inside diameter equal to that of a sphere made from one-tenth of a pound of lead. Each gauge has a set caliber. By far the most common gauges are 12 (0.729 in, 18.5mm diameter) and 20 (0.614 in, 15.6mm), this includes other more or less common gauges, such as the 10, 16, 24, 28, 32, and 67 (.410 bore) gauge.

Different gauges have different typical applications. 12-gauge shotguns are common for hunting geese, large ducks, or other big larger gamebirds; professional skeet and trap shooting; military applications; and home-defense applications. 16-gauge shotguns were once common for hunters who wanted to use only a single shotgun for gamebirds normally pursued with 12 or 20-gauge shotguns, but have become rarer in recent years. 20-gauge shotguns are often used for gamebirds such as doves, smaller ducks, and quail. 28-gauge shotguns are not as common, but are classic quail-hunting guns. .410 gauge shotguns are typically used for squirrel hunting or for sportsmen seeking the challenge of killing game with a smaller load.

Other, less common shotgun cartridges have their own unique uses. Ammunition manufacturer CCI produces 9mm Parabellum (.355 in.) and several other popular pistol calibers up to .45 ACP (11.43mm), as well as smaller calibers such as .22 Long Rifle (5.5mm) and .22 Magnum (5.5mm). These are commonly called snake shot cartridges.^[13] Larger gauges, up to 4 bore, too powerful to shoulder, have been built, but were generally affixed to small boats and referred to as punt guns. These were used for commercial waterfowl hunting, to kill large numbers of birds resting on the water.

Handguns have also been produced that are capable of firing either .45 (Long) Colt or .410 shotgun shells from the same chamber; they are commonly known as "snake guns". Derringers such as the "Snake Slayer and Cowboy Defender" are popular among some outdoors-men in the South and Southwest regions of the United States. There are also some revolvers, such as the Taurus Judge and Smith & Wesson Governor, that are capable of shooting the .45LC/.410 rounds; but as with derringers they are not considered shotguns.

The .410 bore (10.4 mm) is unusual, being measured in inches, and would be approximately 67 "real" gauge, though its short hull versions are nominally called 36-gauge in Europe. It uses a relatively small charge of shot. It is used for hunting and for skeet. Because of its very light recoil (approx 10 N), it is often used as a beginner's gun. However, the small charge and typically tight choke make it more difficult to hit targets. It is also frequently used by expert shooters because of the difficulty, especially in expensive side by side and over/under models for hunting small bird game such as quail and doves.^[14] Inexpensive bolt-action .410 shotguns are a very common first hunting shotgun among young pre-teen hunters, as they are used mostly for hunting squirrels, while additionally teaching bolt-action manipulation skills that will transfer easily later to adult-sized hunting rifles. Most of these young hunters move up to a 20-gauge within a few years, and to 12-gauge shotguns and full-size hunting rifles by their late teens. Still, many who are particularly recoil-averse choose to stay with 20-gauge shotguns all their adult life, as it is a suitable gauge for many popular hunting uses.

A recent innovation is the back-boring of barrels, in which the barrels are bored out slightly larger than their actual gauge. This reduces the compression forces on the shot when it transitions from the chamber to the barrel. This leads to a slight reduction in perceived recoil, and an improvement in shot pattern due to reduced deformation of the shot.

Shot[edit]

Most shotguns are used to fire "a number of ball shot", in addition to slugs and sabots. The ball shot or pellets is for the most part made of lead but this has been partially replaced by bismuth, steel, tungsten-iron, tungsten-nickel-iron and even tungsten polymer loads. Non-toxic loads are required by Federal law for waterfowl hunting in the US, as the shot may be ingested by the waterfowl, which some authorities believe can lead to health problems due to the lead exposure. Shot is termed either birdshot or buckshot depending on the shot size. Informally, birdshot pellets have a diameter smaller than 5 mm (0.20 in) and buckshot are larger than that. Pellet size is indicated by a number; for bird shot this ranges from the smallest 12 (1.2 mm, 0.05 in) to 2 (3.8 mm, 0.15 in) and then BB (4.6 mm, 0.18 in).^[15]

For buckshot, the numbers start and end with 4, 3, 2, 1, 0 ("single-aught"), 00 ("double-aught"), 000 ("triple-aught"), and 0000 ("quadruple-aught"). A different informal distinction is that "bird shot" pellets are small enough that they can be measured into the cartridge by weight, and simply poured in, whereas "buckshot" pellets are so large they must be stacked inside the cartridge in a fixed geometric arrangement to fit. The diameter in hundredths of an inch of bird shot sizes from No. 9 to No. 1 can be obtained by subtracting the shot size from 17. Thus, No. 4 bird shot is 17 – 4 = 13 = 0.13 inches (3.3 mm) in diameter. Different terminology is used outside the United States. In England and Australia, for example, 00 buckshot cartridges are commonly referred to as "S.G." (Swanshot gauge) cartridges.