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An air gun or airgun is a gun that fires
projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found i ...
s
pneumatic Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and ...
ally with
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
or other gases that are mechanically pressurized ''without'' involving any
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...
s, in contrast to a
firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...
, which pressurizes gases ''chemically'' via
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
of
combustible A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the ...
s that generates propulsive energy by breaking molecular bonds. Air guns come in both
long gun A long gun is a category of firearms with long barrels. In small arms, a ''long gun'' or longarm is generally designed to be held by both hands and braced against the shoulder, in contrast to a handgun, which can be fired being held with a single ...
(air rifle) and
handgun A handgun is a short-barrelled gun, typically a firearm, that is designed to be usable with only one hand. It is distinguished from a long gun (i.e. rifle, shotgun or machine gun, etc.), which needs to be held by both hands and also braced ag ...
(air pistol) forms. Both types typically propel metallic projectiles that are either
diabolo The diabolo ( ; commonly misspelled ''diablo'') is a juggling or circus prop consisting of an axle () and two cups (hourglass/egg timer shaped) or discs derived from the Chinese yo-yo. This object is spun using a string attached to two hand ...
-shaped pellets or spherical shots called BBs, although in recent years Minié ball-shaped cylindro-conoidal projectiles called
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a ...
s are gaining more popularity. Certain types of air guns (usually air rifles) may also launch fin-stabilized projectile such as
dart Dart or DART may refer to: * Dart, the equipment in the game of darts Arts, entertainment and media * Dart (comics), an Image Comics superhero * Dart, a character from ''G.I. Joe'' * Dart, a ''Thomas & Friends'' railway engine character * Da ...
s (e.g.,
tranquilizer gun A dart gun is an air rifle that fires a dart. The dart is tipped with a hypodermic needle and filled with a tranquilizer, vaccine, or antibiotic. A dart gun containing a tranquillizer is called a tranquillizer gun ( also spelled tranquilizer, tr ...
s) or hollow-shaft
arrow An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers ...
s (so-called "airbows"). The first air guns were developed as early as the 16th century, and have since been used in
hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
,
shooting sport Shooting sports is a group of competitive and recreational sporting activities involving proficiency tests of accuracy, precision and speed in shooting — the art of using ranged weapons, mainly small arms (firearms and airguns, in forms such ...
and even in
warfare War is an intense armed conflict between states, governments, societies, or paramilitary groups such as mercenaries, insurgents, and militias. It is generally characterized by extreme violence, destruction, and mortality, using regu ...
. There are three different power sources for modern air guns, depending on the design:
spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a h ...
-
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-t ...
, pneumatic, or bottled compressed gas (most commonly
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
).


History

Air guns represent the oldest
pneumatic Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and ...
technology. The oldest existing mechanical air gun, a bellows air gun dating back to about 1580, is in the Livrustkammaren Museum in
Stockholm Stockholm () is the capital and largest city of Sweden as well as the largest urban area in Scandinavia. Approximately 980,000 people live in the municipality, with 1.6 million in the urban area, and 2.4 million in the metropo ...
. This is the time most historians recognize as the beginning of the modern air gun. Throughout 17th to 19th century, air guns in .30 to .51
caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore matc ...
s were used to hunt big-game,
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the re ...
and wild
boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is ...
. These air rifles were charged using a pump to fill an air reservoir and gave velocities from . They were also used in warfare, the most recognized example being the Girandoni air rifle. At that time, they had compelling advantages over the primitive firearms of the day. For example, air guns could be discharged in wet weather and rain (unlike both
matchlock A matchlock or firelock is a historical type of firearm wherein the gunpowder is ignited by a burning piece of rope that is touched to the gunpowder by a mechanism that the musketeer activates by pulling a lever or trigger with his finger. Befor ...
and
flintlock Flintlock is a general term for any firearm that uses a flint-striking ignition mechanism, the first of which appeared in Western Europe in the early 16th century. The term may also apply to a particular form of the mechanism itself, also know ...
musket A musket is a muzzle-loaded long gun that appeared as a smoothbore weapon in the early 16th century, at first as a heavier variant of the arquebus, capable of penetrating plate armour. By the mid-16th century, this type of musket gradually di ...
s), and discharged much faster than muzzle-loading guns. Moreover, they were quieter than a firearm of similar caliber, had no muzzle flash, and were smokeless. Thus, they did not disclose the shooter's position or obscure the shooter's view, unlike the black powder muskets of the 18th and 19th centuries. In the hands of skilled soldiers, they gave the military a distinct advantage. France, Austria and other nations had special
sniper A sniper is a military/paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with high-precision r ...
detachments using air rifles. The Austrian 1770 model was named ''Windbüchse'' (literally "wind rifle" in German). The gun was developed in 1768 or 1769 by the Tyrolean watchmaker, mechanic and gunsmith Bartholomäus Girandoni (1744–1799) and is sometimes referred to as the Girandoni air rifle or Girandoni air gun in literature (the name is also spelled "Girandony," "Giradoni" or "Girardoni".) The ''Windbüchse'' was about long and weighed , about the same size and mass as a conventional
musket A musket is a muzzle-loaded long gun that appeared as a smoothbore weapon in the early 16th century, at first as a heavier variant of the arquebus, capable of penetrating plate armour. By the mid-16th century, this type of musket gradually di ...
. The air reservoir was a removable, club-shaped, butt. The ''Windbüchse'' carried twenty-two .51
caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore matc ...
(13 mm) lead balls in a tubular
magazine A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
. A skilled shooter could fire off one magazine in about thirty seconds. A shot from this air gun could penetrate a wooden board at a hundred paces, an effect roughly equal to that of a modern 9×19mm or
.45 ACP The .45 ACP ( Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it ...
caliber pistol. Circa 1820, the Japanese inventor Kunitomo Ikkansai developed various manufacturing methods for guns, and also created an air gun based on the study of Western knowledge ("
rangaku ''Rangaku'' (Kyūjitai: /Shinjitai: , literally "Dutch learning", and by extension "Western learning") is a body of knowledge developed by Japan through its contacts with the Dutch enclave of Dejima, which allowed Japan to keep abreast of West ...
") acquired from the
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...
in
Dejima , in the 17th century also called Tsukishima ( 築島, "built island"), was an artificial island off Nagasaki, Japan that served as a trading post for the Portuguese (1570–1639) and subsequently the Dutch (1641–1854). For 220 years, i ...
. The
Lewis and Clark Expedition The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gr ...
(1804) carried a reservoir air gun. It held 22 .46 caliber round balls in a tubular magazine mounted on the side of the
barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
. The butt served as the air reservoir and had a working pressure of . The rifle was said to be capable of 22 aimed shots per minute and had a rifled bore of and a groove diameter . One of the first commercially successful and mass-produced air guns was manufactured by the William F. Markham's Markham Air Rifle Company in
Plymouth, Michigan Plymouth is a city in Wayne County, Michigan, United States. The population was 9,370 at the 2020 census. The city of Plymouth is surrounded by Plymouth Township, but the two are administered autonomously. Plymouth is a western suburb of Metro ...
, US. Their first model air gun was the wooden ''Challenger'', marketed in 1886. In response, Clarence Hamilton from the neighboring Plymouth Air Rifle Company (later renamed to Daisy Manufacturing Company in 1895) marketed their all-metal Daisy BB Gun in early 1888, which prompted Markham to respond with their ''Chicago'' model in 1888 followed by the ''King'' model in 1890. The ''Chicago'' model was sold by
Sears, Roebuck Sears, Roebuck and Co. ( ), commonly known as Sears, is an American chain of department stores founded in 1892 by Richard Warren Sears and Alvah Curtis Roebuck and reincorporated in 1906 by Richard Sears and Julius Rosenwald, with what began ...
for 73 cents in its catalog. In 1928, the name of the Markham company was changed to King Air Rifle Company after the company was purchased by Daisy in 1916 after decades of intense competition, and continued to manufacture the "King" model air rifle until 1935 before ceasing operation altogether in the 1940s. During the 1890s, air rifles were used in
Birmingham, England Birmingham ( ) is a city and metropolitan borough in the metropolitan county of West Midlands in England. It is the second-largest city in the United Kingdom with a population of 1.145 million in the city proper, 2.92 million in the We ...
for competitive
target shooting Shooting sports is a group of competitive and recreational sporting activities involving proficiency tests of accuracy, precision and speed in shooting — the art of using ranged weapons, mainly small arms ( firearms and airguns, in forms suc ...
. Matches were held in
public house A pub (short for public house) is a kind of drinking establishment which is licensed to serve alcoholic drinks for consumption on the premises. The term ''public house'' first appeared in the United Kingdom in late 17th century, and wa ...
s, which sponsored shooting teams. Prizes, such as a leg of
mutton Lamb, hogget, and mutton, generically sheep meat, are the meat of domestic sheep, ''Ovis aries''. A sheep in its first year is a lamb and its meat is also lamb. The meat from sheep in their second year is hogget. Older sheep meat is mutton. Gen ...
for the winning team, were paid for by the losing team. The sport became so popular that in 1899, the National Smallbore Rifle Association was created. During this time, over 4,000 air rifle clubs and associations existed across
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It ...
, many of them in Birmingham. During this time, the air gun was associated with
poaching Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
because it could deliver a shot without a significant muzzle report.


Use

Air guns are used for small game
hunting Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
,
pest control Pest control is the regulation or management of a species defined as a pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and will range ...
, recreational
shooting Shooting is the act or process of discharging a projectile from a ranged weapon (such as a gun, bow, crossbow, slingshot, or blowpipe). Even the acts of launching flame, artillery, darts, harpoons, grenades, rockets, and guided missiles ...
(commonly known as plinking) and competitive sports such as the
Olympic Olympic or Olympics may refer to Sports Competitions * Olympic Games, international multi-sport event held since 1896 ** Summer Olympic Games ** Winter Olympic Games * Ancient Olympic Games, ancient multi-sport event held in Olympia, Greece bet ...
10 m Air Rifle and
10 m Air Pistol The 10 meter air pistol is an Olympic shooting event governed by the International Shooting Sport Federation (ISSF). It is similar to 10 meter air rifle in that it is shot with 4.5 mm (or .177) caliber air guns at a distance of 10 m ...
events. Field Target (FT) is a competitive form of
metallic silhouette shooting Metallic silhouette shooting is a group of target shooting disciplines that involves shooting at steel targets representing game animals at varying distances, seeking to knock the metal target over. Metallic silhouette is shot with large bore rif ...
in which the targets are animal-shaped steel targets with a "kill zone" cut-out. Hunter Field Target (HFT) is a variation, using identical equipment, but with differing rules. The distances FT and HFT competitions are shot at range between for HFT & for FT, with varying sizes of "reducers" being used to increase or decrease the size of the kill zone. In the UK, competition power limits are set at the legal maximum for an unlicensed air rifle, i.e. . Air rifle benchrest is an international shooting sport where the objective is to hit a (small) bulls eye target at shooting distance. There are two divisions ARLV and ARHV . The increasing affordability of higher-power pre-charged pneumatic (PCP) rifles has allowed large projectiles and further target distance for competition purposes. For instance, the Extreme Benchrest competition held annually in
Green Valley, Arizona Green Valley is an unincorporated community and census-designated place (CDP) in Pima County, Arizona, United States. The population was 22,616 at the 2020 census. Geography Green Valley is located along the western side of the Santa Cruz ...
allows calibers up to at 75 yd (68.58 m) while the Big Bore Benchrest arm of the same competition at other localities engages targets at .


Powerplant

The component of an airgun that provides the gas pressure needed to propel projectiles is called its ''powerplant''. which uses internally stored pressurized gas; and ''compressed gas'' (most commonly CO2), which uses external sources of pressurized gas.


Spring-piston

A spring-piston air gun (also known as a spring gun or simply a "springer") operates by means of a
spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a h ...
-loaded piston pump assembly contained within a compression chamber separate from the
gun barrel A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces, and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pres ...
. Traditionally, a grease-lubricated steel
coil spring A selection of conical coil springs The most common type of spring is the coil spring, which is made out of a long piece of metal that is wound around itself. Coil springs were in use in Roman times, evidence of this can be found in bronze Fib ...
is used as the powerplant main spring. Before shooting, the user needs to manually cock the gun by flexing a lever connected to the pump assembly, which pulls the pump piston rearwards and compresses the main spring until the rear of the
piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-t ...
engages the sear. When shooting, the trigger is pulled and disengages the sear, allowing the main spring to decompress and release its stored
elastic potential energy Elastic energy is the mechanical potential energy stored in the configuration of a material or physical system as it is subjected to elastic deformation by work performed upon it. Elastic energy occurs when objects are impermanently compressed, ...
, pushing the piston forward, thereby compressing the air in the pump cylinder. Because the pump outlet (located to the front of the pump) is directly behind the pellet seated in the barrel
chamber Chamber or the chamber may refer to: In government and organizations *Chamber of commerce, an organization of business owners to promote commercial interests *Legislative chamber, in politics *Debate chamber, the space or room that houses deliber ...
, once the air pressure has risen enough to overcome the
static friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of t ...
and/or barrel restriction holding back the pellet, the pellet is propelled forward by an expanding column of pressurized air. All this takes place in a fraction of a second, during which the air undergoes adiabatic heating to several hundred degrees and then cools as the air expands. This can also cause a phenomenon referred as "dieseling", where flammable substances in the compression chamber (e.g., petroleum-based lubricant) can be ignited by the compression heat like in a
diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-cal ...
, and lead to an
afterburner An afterburner (or reheat in British English) is an additional combustion component used on some jet engines, mostly those on military supersonic aircraft. Its purpose is to increase thrust, usually for supersonic flight, takeoff, and c ...
effect with (often unpredictable) additional thrusts. This often results in combustion smoke coming out of the muzzle and potential pressure damage to the rubber
O-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more par ...
seal Seal may refer to any of the following: Common uses * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to imp ...
s inside the gun. Dieseling can be made to occur ''intentionally'' to increase power, by coating the pellet with lubricant or
petroleum jelly Petroleum jelly, petrolatum, white petrolatum, soft paraffin, or multi-hydrocarbon, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons (with carbon numbers mainly higher than 25), originally promoted as a topical ointment for its h ...
, although this is normally not recommended as it may result in a more severe damage to the rubber seals. Most spring-piston guns are single-shot
breechloader A breechloader is a firearm in which the user loads the ammunition ( cartridge or shell) via the rear (breech) end of its barrel, as opposed to a muzzleloader, which loads ammunition via the front ( muzzle). Modern firearms are generally br ...
s by nature, but multiple-shot
repeater In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Som ...
s with
magazine A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
feeders have been introduced in recent years by manufacturers such as Gamo,
Umarex Umarex Sportwaffen GmbH & Co. KG is a German manufacturer of air guns (including Umarex air pistols such as the Beretta Elite II), tear-gas and signal pistols, paintball markers under the RAM brand and airsoft guns, based in Arnsberg, North Rhi ...
and Hatsan. Spring-piston guns, especially the high-powered "magnum" guns, are able to achieve muzzle velocities near or exceeding the
speed of sound The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as we ...
. The effort required for the cocking stroke is usually related to the designed power of the gun, with higher muzzle velocities requiring a stiffer spring and hence a greater cocking effort. Spring-piston guns have a practical upper limit of for .177 cal (4.5 mm) pellets, as higher velocities cause unstable pellet flight and loss of accuracy. This is due to the extreme
buffeting Aeroelasticity is the branch of physics and engineering studying the interactions between the inertial, elastic, and aerodynamic forces occurring while an elastic body is exposed to a fluid flow. The study of aeroelasticity may be broadly classif ...
caused when the pellet reaches and surpasses
transonic Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach number, but transoni ...
speed, then slows back down and goes through
sound barrier The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, th ...
again, which is more than enough to destabilize the pellet's flight. Shortly after leaving the barrel, the supersonic pellet falls back below the speed of sound and the shock wave overtakes the pellet, causing its flight stability to be disrupted. Drag increases rapidly as pellets are pushed past the speed of sound, so it is generally better to increase pellet weight to keep velocities subsonic in high-powered guns. Sonic crack from the pellet as it moves with supersonic speed also makes the shot louder sometimes making it possible to be mistaken for firearm discharge. Many shooters have found that velocities in the range offer an ideal balance between power and pellet stability. Spring guns are typically cocked by one of the following mechanisms: * Break-barrel — like a
break action Break action is a type of firearm action in which the barrel or barrels are hinged much like a door and rotate perpendicularly to the bore axis to expose the breech and allow loading and unloading of cartridges. A separate operation may be requir ...
firearm, the barrel is hinged at the junction with the receiver and is flexed downwards to expose the
breech Breech may refer to: * Breech (firearms), the opening at the rear of a gun barrel where the cartridge is inserted in a breech-loading weapon * breech, the lower part of a pulley block * breech, the penetration of a boiler where exhaust gases leave ...
and serves as the cocking lever * Fixed-barrel – the barrel is fixed to the receiver, and the cocking is done with a separate cocking lever ** Underlever – the cocking lever is located underneath the barrel or the receiver and is flexed downwards during cocking ** Sidelever – the cocking lever is located to the side (usually the right side) of the receiver and is flexed sideways during cocking ** Overlever – the cocking lever is located above the barrel and is flexed upwards during cocking, seen in some air pistols * Motorized cocking powered by a rechargeable battery (rare) Spring-piston guns, especially high-powered ("magnum") models, do still
recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force r ...
as a result of the mainspring pushing the piston forward. Although the recoil is less than that of some
cartridge Cartridge may refer to: Objects * Cartridge (firearms), a type of modern ammunition * ROM cartridge, a removable component in an electronic device * Cartridge (respirator), a type of filter used in respirators Other uses * Cartridge (surname), a ...
firearms, it can make the gun difficult to shoot accurately as the spring recoil is in effect while the pellet is still within the barrel. Spring gun recoil also has a sharp forward component, caused by the piston hitting the front end of the pump chamber when the spring has fully decompressed. These rapid double-jerking movements are known to damage
scopes Scope or scopes may refer to: People with the surname * Jamie Scope (born 1986), English footballer * John T. Scopes (1900–1970), central figure in the Scopes Trial regarding the teaching of evolution Arts, media, and entertainment * Cinema ...
not rated for spring gun usage. In addition, the spring often has unpredictable collateral transverse vibrations as well as torquing, both of which can cause accuracy to suffer. These vibrations can be controlled by adding features like close-fitting spring guides or by aftermarket tuning done by "air gunsmiths" who specialize in air gun modifications, a common one being the addition of viscous
silicone grease Silicone grease, sometimes called dielectric grease, is a waterproof grease made by combining a silicone oil with a thickener. Most commonly, the silicone oil is polydimethylsiloxane (PDMS) and the thickener is amorphous fumed silica. Using this ...
to the spring, which both lubricates it and damps vibration. Some shooters hold the gun in a very loose grip (coined as the "artillery hold") that allows the gun to vibrate in a natural and consistent manner. There are also newer models with a floating receiver design that allows the action to slide over the
stock In finance, stock (also capital stock) consists of all the shares by which ownership of a corporation or company is divided.Longman Business English Dictionary: "stock - ''especially AmE'' one of the shares into which ownership of a compan ...
autonomously, thus making the gun less hold-sensitive. The better quality spring guns can have very long service lives, being simple to maintain and repair. Because they deliver the same mechanical energy output on each shot, external ballistics are quite consistent. Most
Olympic Olympic or Olympics may refer to Sports Competitions * Olympic Games, international multi-sport event held since 1896 ** Summer Olympic Games ** Winter Olympic Games * Ancient Olympic Games, ancient multi-sport event held in Olympia, Greece bet ...
air gun competitions through the 1970s and into the 1980s were shot with spring-piston guns, often of the opposing-piston recoil-eliminating type. Beginning in the 1980s, guns powered by compressed/liquefied
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
began to dominate the competition. Today, the guns used at the highest levels of competition are powered by
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
.


Gas spring

Some newer generation air guns incorporate a gas spring (commonly referred to as a ''gas piston'', ''gas ram'', ''gas strut'' or ''nitro piston'') instead of a mechanical spring. The spring itself is essentially a stand-alone enclosed piston pump without outlets and with pressurized air or
inert gas An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. The noble gases often do not react with many substances and were historically referred to ...
(such as
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
) held tightly sealed within the
cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an ...
. When the gun is cocked, the gas inside the cylinder gets further compressed by the piston, stores
potential energy In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors. Common types of potential energy include the gravitational potenti ...
and acts in effect as a
pneumatic Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and ...
accumulator. Gas spring units require higher precision to manufacture since they require a low-friction sliding seal that can withstand the high pressures within when cocked. The advantages of the gas spring include the ability to keep the gun cocked and ready to fire for extended periods of time without long-term spring
fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...
, no twisting
torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
(caused by coil spring expanding) exerted onto the gun, smoother recoil pattern and faster "lock time" (the time between pulling the trigger and the pellet being discharged), which all result in more consistent accuracy. Gas springs perform more reliably in cold climates than coil springs, because metallic coil springs need to be coated with lubricating grease which often thickens in low temperatures causing the gun to "freeze up". Gas springs also have less lateral and longitudinal vibrations than coil springs, hence are usually less "hold-sensitive", making it easier to achieve consistent
shot grouping In shooting sports, a shot grouping, or simply group, is the collective pattern of projectile impacts on a target from multiple consecutive shots taken in one shooting session. The ''tightness'' of the grouping (the proximity of all the shots to ...
s.


Pneumatic

Pneumatic airguns propel the projectiles by utilizing the pneumatic potential energy within
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
, which is pressurized beforehand and stored inside the gun, and then released through valves during shooting. Single-stroke and multi-stroke pump guns utilize an on-board hand pump to pressurize air in an internal reservoir, while pre-charged pneumatic guns' reservoirs are filled from an external source using either a high-pressure stand pump or by decanting air from a larger
diving cylinder A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a sc ...
.


Pump pneumatic

Pump pneumatic air guns, or pump guns, use a lever-operated onboard air pump to pressurize an internal reservoir, and then discharge the stored compressed air during shooting. Depending on the design, pump guns can be either single-stroke or multi-stroke. * In ''single-stroke'' pneumatic air guns (also known as "single pump") a single motion of the cocking lever is all that is required to mechanically compress the air. The single-pump system has always dominated the casual plinking market, and is usually found in target rifles and pistols, where the higher muzzle energy of a multi-stroke pumping system is not required. Single-stroke pneumatic rifles dominated the national and international ISSF 10 metre air rifle shooting events from the 1970s to the 1990s, until being outperformed by the introduction of pre-charged pneumatic (PCP) guns (discussed
below Below may refer to: *Earth * Ground (disambiguation) *Soil *Floor * Bottom (disambiguation) *Less than *Temperatures below freezing *Hell or underworld People with the surname *Ernst von Below (1863–1955), German World War I general *Fred Below ...
). * ''Multi-stroke'' pneumatic air guns (also known as "multi-pump") use multiple pumpings to achieve variable power levels in order to adapt for both long or short-range shooting. These air guns are usually single-shot, where each shot requires approximately 5 strokes. However, up to five shots are possible, usually requiring approximately 10 to 20 strokes, as long as the air reservoir is capable of storing higher pressure. For safety reasons, most multi-stroke guns are usually designed to have their pump lever jam when the reservoir has reached its maximum pressure limit, so the user can no longer pump the gun until it's discharged. The maximum pressure limit for the reservoir is approximately 20 to 30 strokes.


Pre-charged pneumatic

Pre-charged pneumatic air guns (PCPs) have their internal reservoir pre-filled from an external air source (such as a
diving cylinder A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a sc ...
or
air compressor An air compressor is a pneumatic device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces m ...
, or by manual charging with a high-pressure stand pump), and remain pressurized until depleted after repeated shooting. During shooting, the hammer strikes the reservior's release valve, allowing a set volume of the pressurized air to be discharged into the chamber and propel the projectile. Depending on the release valve design, PCP air guns can be categorized into two types – ''unregulated'' and ''regulated'' (which has either a mechanical or electronic regulator valve). In addition to
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
, custom PCP models using compressed pure
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
and even compressed
helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic ta ...
have also been recently developed. Because of the need for cylinders or charging systems, PCP guns have higher initial costs but much lower operating costs when compared to CO2 rifles, and have superior performance over ordinary pump guns. Having no significant movement of heavy mechanical parts during the discharge cycle, PCP airgun designs produce lower
recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force r ...
, and can shoot as many as 100 shots per charge depending on the tank/reservoir size. The ready supply of air has allowed the development of semi- and fully automatic air guns. PCP guns are very popular in
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
because of their accuracy and ease of use. They are widely utilized in ISSF 10 metre air pistol and rifle shooting events and the sport of Field Target shooting, and are usually fitted with
telescopic sight A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a '' reticle'' – mounted in a focally appropriate ...
s. Early stand pump designs encountered problems of fatigue (both human and mechanical), temperature warping, and condensation – none of which are beneficial to accurate shooting or the airguns' longevity. Modern stand pumps have multi-stage chambers and built-in air filtration systems and have overcome many of these problems. Using
scuba Scuba may refer to: * Scuba diving ** Scuba set, the equipment used for scuba (Self-Contained Underwater Breathing Apparatus) diving * Scuba, an in-memory database developed by Facebook * Submillimetre Common-User Bolometer Array, either of two in ...
-quality air decanted from a diving cylinder provides consistently clean, dry, high-pressure air. During the typical PCP's discharge cycle, the hammer of the rifle is released by the sear to strike the bash valve. The hammer may move rearwards or forwards, unlike firearms where the hammer almost always moves forward. The valve is held closed by a spring and the pressure of the air in the reservoir. The pressure of the spring is constant, and the pressure of the air released (which is also known as the ''working pressure'') decreases with each successive shot. As a result, when the reservoir pressure is high, the valve opens less fully and closes faster than when the reservoir pressure is lower, resulting in a similar total volume of air flowing past the valve with each shot. This results in a degree of partial self-regulation that gives a greater consistency of velocity from shot to shot, which corresponds to the middle "plateau" phase of the gun's shot-to-shot
muzzle velocity Muzzle velocity is the speed of a projectile ( bullet, pellet, slug, ball/ shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately ...
profile (also known as the ''power curve'' ). Well-designed PCP will display good shot-to-shot consistency over a long period, as the air reservoir is being depleted. Other PCP rifles and pistols are regulated, i.e. the firing valve operates within a secondary chamber separated from the main air reservoir by the regulator body. The regulator maintains the pressure within this secondary chamber at a set pressure (lower than the main reservoir's) until the main reservoir's pressure drops to the point where it can no longer do so. As a result, shot-to-shot consistency is maintained for longer than in an unregulated rifle, and the gun can also output more shots due to reduced waste of reservoir pressure.


Compressed gas

Compressed gas guns, also known as ''CG gun's, are essentially pneumatic airguns utilizing detachable pressure reservoirs in the form of prefilled external
gas cylinder A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. High-pressure gas cylinders are also called ''bottles''. Inside the cylinder the stored contents may be in a state of compressed gas, vap ...
s (often with built-in regulator valves), and are commonly referred to as ''CO2 gun''s due to the ubiquitous commercial use of bottled liquid carbon dioxide. However, more recent high-end models sometimes use larger
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
/
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
(known as HPA or "N2") cylinders, which have higher operating pressures and better thermal stability.


CO2

CO2 guns, like other pneumatic guns using compressed air, offer power for repeated shots in a compact package without the need for complex pumping or filling mechanisms. The ability to store power for repeated shots also means that repeating arms are possible. There are many replica revolvers and semi-automatic pistols on the market that use CO2 power. Most CO2 guns use a disposable cylinder called a "
Powerlet Crosman Corporation is an American designer, manufacturer and supplier of shooting sport products, with a long-standing presence in airgun design and a tradition of producing pellet and BB guns. Crosman is also a producer of many varieties of a ...
" cartridge, that is often purchased with of pressurized CO2 gas, although some, usually more expensive models, use larger refillable CO2 reservoirs like those typically used with
paintball marker A paintball marker, also known as a paintball gun, paint gun, or simply marker, is an air gun used in the shooting sport of paintball, and the main piece of paintball equipment. Paintball markers use compressed gas, such as carbon dioxide (CO ...
s. CO2 guns are popular for training, as the guns and ammunition are inexpensive, relatively safe to use, and no specialized facilities are needed for safety. In addition, they can be purchased and owned in areas where firearms possession is either strictly controlled or banned outright. Most CO2 powered guns are relatively inexpensive, and there are a few precision target guns available that use CO2.


High-pressure air

High-pressure air Paintball is an equipment-intensive sport and in order to safely conduct a game, every player requires a paintball marker, marker with propellant to fire the paint, a mask to protect the eyes and face, Paintball equipment#Paintballs, paintballs, a ...
(HPA) system, or ''N2'', was originally developed for paintball markers as a replacement for CO2 cartridges, and uses Powerlet interface-compatible
diving cylinder A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a sc ...
s filled with either pure
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
or
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
(which is 78% nitrogen). Because nitrogen is more inert than CO2, it remains in the gaseous state longer when compressed; when it expands, it cools due to the Joule-Thomson effect but at a far lower rate than liquid CO2 because there is no change in
state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States * ''Our S ...
from liquid to gas. This
thermostability In materials science and molecular biology, thermostability is the ability of a substance to resist irreversible change in its chemical or physical structure, often by resisting decomposition or polymerization, at a high relative temperatu ...
reduces the variation in output pressure associated with rapid successions of firing cycles, improving accuracy and reliability in extreme climates. However, because compressed air is stored at higher pressures (up to ) than liquid CO2 (stored at around ), HPA cylinders are more expensive. Cylinders smaller than may not even last as long as a standard CO2 cartridge when subjected to frequent uses. It is also possible to power an HPA-compatible gun directly from a plug-in
air compressor An air compressor is a pneumatic device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in pressurized air (i.e., compressed air). By one of several methods, an air compressor forces m ...
without using a gas cylinder, though this type of setup is rare.


Air cartridge system

First developed in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
during the 1980s as the Saxby-Palmer Ensign, and then by Brocock as the "Brocock Air Cartridge System" (BACS) and later into the "Tandem Air Cartridge" (TAC), this variation of the pre-charged pneumatic design have no pressure reservoir built into the gun, but instead use removable and reusable metallic
gas cylinder A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. High-pressure gas cylinders are also called ''bottles''. Inside the cylinder the stored contents may be in a state of compressed gas, vap ...
s often known as "Brocock cartridges" after its British manufacturer. Each air cartridge is essentially a self-contained gas reservoir housed inside a
cartridge case A cartridge or a round is a type of pre-assembled firearm ammunition packaging a projectile (bullet, shot, or slug), a propellant substance (usually either smokeless powder or black powder) and an ignition device (primer) within a metallic, ...
(usually in the size of a
.38 Special The .38 Special, also commonly known as .38 S&W Special (not to be confused with .38 S&W), .38 Smith & Wesson Special, .38 Spl, .38 Spc, (pronounced "thirty-eight special"), or 9x29mmR is a rimmed, centerfire cartridge designed by Smith & ...
), with an internal bash valve designed to release the content when the base of the cartridge is struck. Prior to shooting, each cartridge is pre-filled with sufficient
compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, an ...
for one shot (typically via a multi-stroke hand pump) and has a .177/
.22 caliber .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm). Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO. .22 inch is also a popular ...
pellet pre-seated to its front slot, and the entire cartridge is then inserted into a
chamber Chamber or the chamber may refer to: In government and organizations *Chamber of commerce, an organization of business owners to promote commercial interests *Legislative chamber, in politics *Debate chamber, the space or room that houses deliber ...
in the
gun barrel A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces, and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pres ...
. When shooting, the
hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as wi ...
hits the rear of the air cartridge, mimicking the function of a
centerfire ammunition Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center A centerfire cartridge is a firearm metallic cartridge whose primer is located at the center of the base of its casing (i.e. "case head"). Unlike rim ...
. This allows the airgun to be constructed and operated in similar fashions to genuine firearms. It also allows for higher shot consistency because each cartridge can be easily filled to an identical air charge, essentially removing the "power curve" of conventional PCP guns and bypassing any need for regulators. It also simplifies the magazine feed design and eliminates the risk of deforming the projectiles when the action seats each pellet, as the soft lead pellet is protected from contact with the action probe by the harder cartridge casing. The air cartridge system, both in the
rifle A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...
and
revolver A revolver (also called a wheel gun) is a repeating firearm, repeating handgun that has at least one gun barrel, barrel and uses a revolving cylinder (firearms), cylinder containing multiple chamber (firearms), chambers (each holding a single ...
forms, was at the peak of its popularity throughout the 1990s. The popularity of the Brocock range was such that, by 2002, estimates put the number of air cartridge guns in circulation around 70,000-80,000. However, a small number of incidents relating to the alleged illegal conversion of (mainly) Brococks to allow them to discharge live ammunition sparked a
media frenzy Media circus is a colloquial metaphor, or idiom, describing a news event for which the level of media coverage—measured by such factors as the number of reporters at the scene and the amount of material broadcast or published—is perceived to ...
. In early 2002, the BBC reported that figures from the
National Criminal Intelligence Service The National Criminal Intelligence Service (NCIS) was a United Kingdom policing agency. Following the Police and Criminal Justice Act 2001, NCIS returned to direct funding by the Home Office in 2002 and was a non-departmental public body. On 1 A ...
showed converted Brococks accounted for 35 per cent of all guns recovered by the police, and David McCrone, firearms adviser to the Association of Chief Police Officers and Deputy Chief Constable of
Greater Manchester Police Greater Manchester Police (GMP) is the territorial police force responsible for law enforcement within the metropolitan county of Greater Manchester in North West England. , Greater Manchester Police employed 6,866 police officers, 3,524 memb ...
, told the BBC's ''
Newsnight ''Newsnight'' (or ''BBC Newsnight'') is BBC Two's news and current affairs programme, providing in-depth investigation and analysis of the stories behind the day's headlines. The programme is broadcast on weekdays at 22:30. and is also availa ...
'' "there is evidence which would justify banning them". After the
UK government ga, Rialtas a Shoilse gd, Riaghaltas a Mhòrachd , image = HM Government logo.svg , image_size = 220px , image2 = Royal Coat of Arms of the United Kingdom (HM Government).svg , image_size2 = 180px , caption = Royal Arms , date_est ...
implemented the
Anti-Social Behaviour Act 2003 The Anti-Social Behaviour Act 2003 (c.38) is an Act of the Parliament of the United Kingdom which almost entirely applies only to England and Wales. The Act, championed by then Home Secretary, David Blunkett, was passed in 2003. As well as str ...
in January 2004, it became illegal to possess such airguns without a
firearm certificate In the United Kingdom, access by the general public to firearms is subject to some of the strictest control measures in the world. However, fulfilment of the criteria and requirements as laid out by the laws results in the vast majority of fir ...
in the United Kingdom. Brocock subsequently ceased production of all air cartridge systems and turned to focus primarily on PCP airguns.


Ammunition


Pellet

The most popular ammunition used in rifled air guns is made of lead, a heavy metal. Lead is highly poisonous (whether inhaled or swallowed), affecting almost every organ and system in the human body. For this reason, lead-free pellets are becoming increasingly popular, and are available in all major shapes and styles, just like traditional lead pellets. By far the most popular shape is the wasp-waisted
diabolo The diabolo ( ; commonly misspelled ''diablo'') is a juggling or circus prop consisting of an axle () and two cups (hourglass/egg timer shaped) or discs derived from the Chinese yo-yo. This object is spun using a string attached to two hand ...
pellet, which has two sections – a solid front portion called the "head", which contains the
center of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...
and is available in a variety of shapes and styles such as flat ( wadcutter), round (domed), cone-shaped (pointed) and pitted (
hollow point upright=0.2, Cross-section of a hollow-point bullet; proportions are those of a .22 Long Rifle cartridge Jacketed soft point (JSP) round. Right: Jacketed hollow-point (JHP) round. JSP is a semi-jacketed round as the jacket does not extend to ...
); and a hollowed, thin-walled
conical A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines c ...
rear portion called the "skirt", which expands and fully engages the bore to provide a good
seal Seal may refer to any of the following: Common uses * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to imp ...
and thus allows maximal efficiency in pellet propulsion during shooting. In flight, the skirt has greater drag-to-weight ratio than the head and exerts a rearward pull behind the center of mass, similar to that of a
shuttlecock A shuttlecock (also called a birdie or shuttle) is a high-drag projectile used in the sport of badminton Badminton is a racquet sport played using racquets to hit a shuttlecock across a net. Although it may be played with larger tea ...
. This produces a phenomenon known as ''drag stabilization'', which helps to counteract yawing and maintain a consistent
flight path In the United States, airways or air routes are defined by the Federal Aviation Administration (FAA) in two ways: "VOR Federal airways and Low/Medium Frequency (L/MF) (Colored) Federal airways" These are designated routes which aeroplanes f ...
. However, the diabolo shape also means that the overall pellet will have poor
ballistic coefficient In ballistics, the ballistic coefficient (BC, ''C'') of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the ...
and tends to lose energy quickly and be more unstable especially in the transonic region (272–408 m/s ~ 893–1340 ft/s). Diabolo pellets are conventionally made from
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...
, but are widely available in non-lead alternatives, such as tin, or a combination of materials such as
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
or
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
alloys with
polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
tips. A variety of lead-free pellets are offered by all major pellet manufacturers, including H&N Sport, RWS, JSB, Gamo, and others. Since lead is very dense, it has a higher ballistic coefficient than lightweight alternatives such as tin, copper, or plastic. At the present time, the airgun industry does not mass-produce dense alternatives to lead with a high ballistic coefficient for long-range shooting.


Slug

Some manufacturers also have recently introduced the more cylindro-conoidal-shaped "
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a ...
" pellets for the more powerful modern PCP air rifles. Compared to the commonly used diabolo pellets, these slug pellets resemble Minié balls and have more contact surface with the bore and hence need greater propelling force to overcome friction, but have better
aerodynamics Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dy ...
,
ballistic coefficient In ballistics, the ballistic coefficient (BC, ''C'') of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the ...
, and longer effective ranges due to the more similar shape to firearm
bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...
s, however they also require a fully
rifled In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the ...
barrel for spin stabilization in flight. They are also made of lead, and precautions should be taken when handling them, or preparing animals for food, as lead fragments can be easily missed inside the meat.


BB

The BB shot was once the most common airgun ammunition in the US, thanks to the popularity of
Daisy Daisy, Daisies or DAISY may refer to: Plants * ''Bellis perennis'', the common daisy, lawn daisy or English daisy, a European species Other plants known as daisy * Asteraceae, daisy family ** '' Euryops chrysanthemoides'', African bush daisy ** ' ...
’s line of BB airguns. A BB is a small metallic ball in 4.5 mm/ .177" diameter, typically made of steel (with a copper or zinc coating) or lead. Originally called the "
round shot A round shot (also called solid shot or simply ball) is a solid spherical projectile without explosive charge, launched from a gun. Its diameter is slightly less than the bore of the barrel from which it is shot. A round shot fired from a lar ...
", the contemporary name came from the "BB"- size lead birdshot used in
shotgun shell A shotgun shell, shotshell or simply shell is a type of rim (firearms), rimmed, cylindrical (straight-walled) cartridge (firearms), cartridges used specifically in shotguns, and is typically loaded with numerous small, pellets (petrology), pellet ...
s, which the first BB gun invented in 1886 was designed to shoot. Steel BBs can be acceptably accurate at short distances when fired from properly designed
BB gun A BB gun is a type of air gun designed to shoot metallic spherical projectiles called BBs (not to be confused with similar-looking bearing balls), which are approximately the same size as BB-size lead birdshot used on shotguns ( in diamete ...
s with
smoothbore A smoothbore weapon is one that has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars. History Early firearms had smoothly bored barrels that fired projectiles without signi ...
barrels. Lead #3 buckshot pellets can be used in .25" caliber airguns as if they were large BBs. Due to the hardness of the steel, steel BBs cannot "take" to rifled barrels, which is why they are undersized (4.4 mm ball against 4.5 mm bore) to allow them to be used in .177" rifled barrels, which when used in this configuration can in effect be considered
smoothbore A smoothbore weapon is one that has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars. History Early firearms had smoothly bored barrels that fired projectiles without signi ...
, but with a poorer gas-seal, and if 4.5 mm diameter BBs are used, they would jam in the bore. Therefore, steel BBs lack the spin stabilization required for long-range accuracy, and usage in any but the cheapest rifled guns is discouraged. The softer lead BBs however can be used in rifled barrels. Typically BBs are used for indoor practice, casual outdoor plinking, training children, or to save money, as they are significantly cheaper than pellets. Replica pistols allow people to train with a BB gun, saving a lot of money to centerfire firearm cartridges. Care should be exercised to avoid ricochet, and safety glasses are recommended. Recently, manufacturers have created frangible BBs, which break apart and do not ricochet, reducing the hazards associated with BB guns. Some shotgunners use sightless BB rifles to train in instinctive shooting. Similar guns were also used briefly by the United States Army in a Vietnam-era instinctive shooting program called "
Quick Kill Quick Kill is an active protection system (APS) designed to destroy incoming anti-tank missiles, rockets, and grenades. The Quick Kill system is designed and produced by Raytheon for the U.S. Army. The Quick Kill system was part of the Uni ...
".


Darts and arrows

In the 18th and 19th centuries, air gun darts were popular, largely because they could be reused. Although less popular now, several different types of darts are made to be used in air guns, but it is not recommended that darts be used in air guns with
rifled In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the ...
bores or in spring-powered air guns. Air guns that shoot darts are sometimes called ''dart guns'', and ''
tranquilizer gun A dart gun is an air rifle that fires a dart. The dart is tipped with a hypodermic needle and filled with a tranquilizer, vaccine, or antibiotic. A dart gun containing a tranquillizer is called a tranquillizer gun ( also spelled tranquilizer, tr ...
s'' if the darts used are loaded with
anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into two ...
(
tranquilizer A tranquilizer is a drug that is designed for the treatment of anxiety, fear, tension, agitation, and disturbances of the mind, specifically to reduce states of anxiety and tension. Etymology Tranquilizer, as a term, was first used by F.F. Yonk ...
) compounds. Some modern air guns are designed to discharge arrows and are called ''arrow guns'' or sometimes ''airbows''. These arrows are designed with a hollow shaft that is open in the rear where the nock would normally be. When loaded, the hollow arrow shaft is slid rearwards over a barrel whose external diameter is only fractionally smaller than the shaft's interior diameter, providing a close-enough fitting that minimizes rattling and gives a reasonable enveloping
seal Seal may refer to any of the following: Common uses * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to imp ...
without causing too much
friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of ...
. During shooting, the trigger releases high-pressure air from the barrel to the front portion of the hollow arrow shaft, pushing the arrow forward. Such air guns can shoot arrows at launch velocities rivalling or even exceeding high-end
crossbow A crossbow is a ranged weapon using an Elasticity (physics), elastic launching device consisting of a Bow and arrow, bow-like assembly called a ''prod'', mounted horizontally on a main frame called a ''tiller'', which is hand-held in a similar ...
s, while retaining consistency of precision unaffected by archer's paradox, but they are also more expensive to set up and maintain.


Laser beam

The
modern pentathlon The modern pentathlon is an Olympic sport consisting of fencing (one-touch épée), freestyle swimming, equestrian show jumping, pistol shooting, and cross country running. The event is inspired by the traditional pentathlon held during the anc ...
has since 2009 included a laser-run event that replaced the traditional cross country run of 3,200 metres and timed air-pistol shoot. The competitors run 4 laps of 800 m combined with 4 rounds of firing. The pistols used are modified air pistols that fire an eye-safe laser beam towards a target at the same time as a discharge of air. This has made the organisation of the events easier from a safety point of view and allows competitors to travel more easily with their weapons.


Calibers

The most common air gun
caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel bore – regardless of how or where the bore is measured and whether the finished bore matc ...
s are * .177 (4.5 mm): the most common caliber. Mandated by the ISSF for use in international target shooting competition at 10m, up to Olympic level in both rifle and pistol events. It has also been adopted by most National Governing Bodies for domestic use in similar target shooting events. It has the flattest trajectory of all the calibers for a given energy level. At suitable energy levels it can be used effectively for hunting. *
.22 .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm). Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO. .22 inch is also a popular ...
(5.5 mm & 5.6 mm): for hunting and general use. In recent years air rifles and pistols in .22" (and some other calibers) have been allowed for use in both domestic and international target shooting in events not controlled by the ISSF. Most notably in FT/HFT and Smallbore Benchrest competitions. These events often allow the use of any caliber air gun, up to a maximum which is often .22", rather than a fixed caliber. Other less common traditional calibers include: * .20 (5 mm): initially proprietary to the Sheridan multi-pump pneumatic air rifle, later more widely used. * .25 (6.35 mm): the largest commonly available caliber for most of the 20th century. *
.30 The 7.62 mm caliber is a nominal caliber used for a number of different cartridges. Historically, this class of cartridge was commonly known as .30 caliber, the imperial unit and customary unit equivalent, and was most commonly used for i ...
(7.62 mm): the current largest available for non-PCP powered airguns Larger caliber air rifles suitable for hunting large animals are offered by major manufacturers. These are usually PCP guns. The major calibers available are: * .357 (9mm) *
.45 This is a list of firearm cartridges which have bullets in the to caliber range. *''Length'' refers to the cartridge case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Cartridge case or casing, a ...
(11.43 mm) *
.50 This is a list of firearm cartridges which have bullets in the to caliber range. *''Length'' refers to the cartridge case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Cartridge case or casing, a ...
(12.7 mm) * .58 (14.5 mm) Custom air guns are available in even larger calibers such as 20 mm (0.79") or .87 (22.1 mm).


Legislation

While in some countries air guns are not subject to any specific regulation, in most, there are laws which differ widely. Each jurisdiction has its definition of an air gun. Regulations may vary for weapons of different bore,
muzzle energy Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. Without consideration of factors such as aerodynamics and gravity for the sake of comparison, muzzle energy is used as a rough indication of the de ...
,
velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...
, or ammunition material. Guns designed to fire metal pellets are often more tightly controlled than
airsoft Airsoft is a team game in which participants eliminate opposing players by tagging them out of play with spherical plastic projectiles shot with mock air weapons(usually powered by an electronic motor) called airsoft guns. Although similar ...
weapons. There may be a minimum age for possession, and sales of both air guns and ammunition may be restricted. Some areas require permits and background checks similar to those required for propellant type firearms.


Safety and misuse

While historical air guns have been made specifically for warfare, modern air guns can also be deadly. In medical literature, modern air guns have been noted as a cause of death. This has been the case for guns of caliber .177 and .22 that are within the legal muzzle energy of air guns in the United Kingdom.


See also

*
Blowgun A blowgun (also called a blowpipe or blow tube) is a simple ranged weapon consisting of a long narrow tube for shooting light projectiles such as darts. It operates by having the projectile placed inside the pipe and using the force created by f ...
*
Marksmanship A marksman is a person who is skilled in precision shooting using projectile weapons (in modern days most commonly an accurized scoped long gun such as designated marksman rifle or a sniper rifle) to shoot at high-value targets at longer-th ...
*
Airsoft Airsoft is a team game in which participants eliminate opposing players by tagging them out of play with spherical plastic projectiles shot with mock air weapons(usually powered by an electronic motor) called airsoft guns. Although similar ...
*
Paintball Paintball is a competitive team shooting sport in which players eliminate opponents from play by hitting them with spherical dye-filled gelatin capsules called paintballs that break upon impact. Paintballs are usually shot using low-energy a ...


References


External links


Tom Gaylord's History of Airguns
{{DEFAULTSORT:Air Gun Hunting equipment Pneumatic weapons Swedish inventions Rifles Pistols