Pellet (air gun)

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Top row .22 caliber (5.5 mm); bottom row .177 (4.5 mm) caliber.
From left to right, wadcutter, domed (round nose), hollow point and pointed pellets. Air-gun-pellets.jpg
Top row .22 caliber (5.5 mm); bottom row .177 (4.5 mm) caliber.
From left to right, wadcutter, domed (round nose), hollow point and pointed pellets.
4.5mm pellet exiting an air pistol, photographed with a high speed air-gap flash Air pistol.JPG
4.5mm pellet exiting an air pistol, photographed with a high speed air-gap flash

A pellet is a non-spherical projectile designed to be shot from an air gun, and an airgun that shoots such pellets is commonly known as a pellet gun. Air gun pellets differ from bullets and shot used in firearms in terms of the pressures encountered; airguns operate at pressures as low as 50 atmospheres, [1] while firearms operate at thousands of atmospheres. Airguns generally use a slightly undersized projectile that is designed to obturate upon shooting so as to seal the bore, and engage the rifling;[ citation needed ] firearms have sufficient pressure to force a slightly oversized bullet to fit the bore in order to form a tight seal. Since pellets may be shot through a smoothbore barrel, they are often designed to be inherently stable, much like the Foster slugs used in smoothbore shotguns.

Contents

Types

Diabolo pellet

Hornet Cal. 4,5mm (.177). Special pellet for hunting purposes. Lead with a point of brass. Extremely high penetrating power Hornet 45.jpg
Hornet Cal. 4,5mm (.177). Special pellet for hunting purposes. Lead with a point of brass. Extremely high penetrating power
Hunter Impact Cal. 4,5mm (.177). Pellet for hunting purposes. Lead with a point of synthetic polymers Hunter Impact 45.jpg
Hunter Impact Cal. 4,5mm (.177). Pellet for hunting purposes. Lead with a point of synthetic polymers

The diabolo pellet (or "wasp waist pellet") is the most common design traditionally found in airguns. It consists of a solid front portion called the head, which can have a flat ("wadcutter"), hemispherical ("round nose"), hollow point or conical ("pointed") front end profile, and a thin-walled funnel-shaped hollow rear portion called the skirt, joined together by an hourglass-looking narrow mid-section known as the waist, giving the whole pellet the shape of a diabolo. The head is usually sized to just touch the rifling, and this keeps the pellet centered in the bore while keeping the friction as low as possible. The effect of friction is used in order to keep the pellet stationary until the piston has reached the end of its travel, compressing as much air as is possible.[ citation needed ] The thin hollow skirt is made of a malleable material, usually lead, although non-toxic alternatives are available that use tin or even plastic. During shooting, the skirt flares out and obturates the bore when pressure builds up behind it to provide a good seal that allows efficient pellet acceleration, and engages the rifling whereby imparting spin. In a smoothbore barrel, the skirt will still flare to provide a tight seal, but since there is no rifling the pellet will not spin, and is less accurate.

Because the majority of the pellet's mass resides in the solid head in the front, and the hollow skirt in the back generates significant drag during flight, this creates drag stability that will counteract yawing and help to maintain consistent trajectories. However, such stability is limited, and if the pellet's speed exceeds what the aerodynamics allow it will become unstable and start tumbling in flight. When this happens, the pellet can hit the target sideways and leave behind a keyhole-shaped impact hole on the target paper, instead of a clean round hole as expected from a direct frontal hit. This phenomenon is known as keyholing.

Pellets are designed to travel at subsonic speeds. High velocities can cause light pellets to overly deform, or even break apart in flight. The transition from subsonic to supersonic velocities will cause almost all pellets to tumble. The closer a pellet gets to the speed of sound, the more unstable it becomes. This is a problem for high-powered "magnum" break-barrel and pre-charged pneumatic air rifles, which are capable of pushing lighter pellets beyond the sound barrier. A few companies[ example needed ] have addressed this issue by manufacturing heavier-than-normal pellets for use in these high powered air guns.[ citation needed ] The heavier weight of these pellets ensures lower muzzle velocities, resulting in less chance of tumbling and more overall accuracy. Their weight also makes them sectionally denser and less susceptible to wind deviation and drag deceleration, and thus imparts better external and terminal ballistic performance.

Slug pellet

Eisenherz Cal. 4,5mm (.177). Plastic-coated pellet with a core of hard metal. For hunting purposes. Eisenherz 45.jpg
Eisenherz Cal. 4,5mm (.177). Plastic-coated pellet with a core of hard metal. For hunting purposes.
Plastic-coated pellets with a pointed steel core: Highest possible penetration power. Top: For rifles, bottom: for CO2-pistols with a revolver magazine Eisenherz long short.jpg
Plastic-coated pellets with a pointed steel core: Highest possible penetration power. Top: For rifles, bottom: for CO2-pistols with a revolver magazine

Recently, some manufacturers also have introduced the more cylindro-conoidally shaped "slug" pellets for some of the more powerful modern PCP air rifles. Contrasted to the commonly used diabolo pellets, these slug pellets resemble Minié balls, with cannelures and a hollow base, and have more contact surface with the bore and hence need greater propelling force to overcome friction, but they have better ballistic coefficients and thus longer effective ranges due to the more aerodynamic shape. Because these slug pellets have no skirts to generate enough drag stability in flight, they rely on spin stabilization from a fully rifled barrel.

Performance Ballistic Alloy

Performance Ballistic Alloy (PBA) pellets are made from a non-lead alloy and designed to penetrate a target whereas lead pellets are designed to expand or mushroom and release its energy inside the target. PBA pellets minimize weight while retaining hardness because of their alloy composition. These pellets are most notable for increasing an air rifle’s or pistol's maximum feet per second (FPS) potential due to their light weight.

Match shooting use

A H&N Final Match Pistol 4.5 mm (.177 in) match diabolo pellet HundN FinaleMatchLP Front.jpg
A H&N Final Match Pistol 4.5 mm (.177 in) match diabolo pellet

Match pellets are used for the 10 metre air rifle and 10 metre air pistol disciplines. These 4.5 mm (0.177 in) calibre pellets have wadcutter heads, meaning the front is (nearly) flat, that leave clean, hole punch-like round holes in paper targets for easy scoring. Match pellets are offered in tins and more elaborate packagings that avoid deformation and other damage that could impair their uniformity.

Match pellets are made of soft lead (a lead alloy with low antimony content). The antimony content is used to control the hardness of the soft lead alloy. It is a very soft alloy, which makes it easy to process. Since the soft lead alloy is prone to strongly deform when striking a bullet catcher, it rapidly loses its kinetic energy and will not easily bounce off. Lead is toxic and hazardous to the environment, so when shooting with lead pellets, precautions should be taken.

Match air gun shooters are encouraged to perform shooting group tests with their gun clamped in a fixed rest in order to establish which particular pellet type performs best for their air gun. [2] [3] To facilitate maximum performance out of various air guns the leading match pellet manufacturers produce pellets in graduated weight variants (the light/high speed variants are often marketed for air pistol use) and with graduated "head sizes", which means the pellets are offered with front diameters from 4.48 mm (0.176 in) up to 4.52 mm (0.178 in).

However at higher and top competitive levels, even these variations are thought too coarse-grained and match pellets are batch tested; that is, the specific gun is mounted in a machine rest test rig and pellets from a specific production run on a specific machine with the same ingredients fed into the process (a batch) are test-fired through the gun. [4] Many different batches will be tested in this manner, and the pellets which give the smallest consistent group size without fliers (shots which fall outside of the main group) will be selected (small but inconsistent group sizes are not useful to a top competitor); and the shooter will then purchase several tens of thousands of pellets from that batch. Group sizes of 4.5 mm (0.177 in) diameter are theoretically possible, but practically shot groups of 5.0 mm (0.197 in) are considered highly competitive. [5] Unbatched ammunition, especially if the air gun is not regularly cleaned, is generally thought to be capable of only 8.0 mm (0.315 in) diameter group sizes. Batch testing match pellets for a particular gun is not generally thought to be worthwhile until the shooter reaches a high proficiency level (around the 95% level (570 for men, 380 for women).

See also

Related Research Articles

A rifle is a long-barrelled 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 both hands and braced firmly against the shooter's shoulder via a buttstock for stability during shooting. Rifles are used extensively in warfare, law enforcement, hunting and shooting sports.

Shotgun Firearm intended for firing a bolus of small pellets

A shotgun is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which usually discharges numerous small pellet-like spherical sub-projectiles called shot, or sometimes a single solid projectile called a slug. Shotguns are most commonly smoothbore firearms, meaning that their gun barrels have no rifling on the inner wall, but rifled barrels for shooting slugs are also available.

Bullet

A bullet is a projectile and a component of firearm ammunition that is expelled from a gun barrel during shooting. The term is from Middle French and originated as the diminutive of the word boulle (boullet), which means "small ball". Bullets are made of a variety of materials such as copper, lead, steel, polymer, rubber and even wax. They are available either singly, as in muzzle-loading and cap and ball firearms, or as components of paper cartridges, but much more commonly in the form of metallic cartridges. Bullets are made in various shapes and constructions depending on the intended applications, including specialized functions such as hunting, target shooting, training and combat.

Rifling Gunsmithing technique

In firearms, rifling is the helical groovings that are machined 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. This spin serves to gyroscopically stabilize the projectile by conservation of angular momentum, improving its aerodynamic stability and accuracy over smoothbore designs.

Air gun Gun that uses compressed air to launch projectiles

An air gun, air rifle or airgun, is a gun that shoots projectiles pneumatically with compressed air or other gases that are mechanically pressurized without involving any chemical reactions, in contrast to a firearm, which pressurizes gases chemically via oxidation of combustible propellants that generates propulsive energy by breaking molecular bonds.

Terminal ballistics

Terminal ballistics, a sub-field of ballistics, is the study of the behavior and effects of a projectile when it hits and transfers its energy to a target. Bullet design and the velocity of impact largely determine the effectiveness of its impact.

BB gun Air gun that uses metallic ball projectiles called BBs

A BB gun is a type of air gun designed to shoot metallic ball projectiles called BBs, which are approximately the same size as BB-size lead birdshot. Modern BB guns usually have a smoothbore barrel with a 4.5 mm (0.177 in) caliber, and use steel balls that measure 4.3–4.4 mm (0.171–0.173 in) in diameter and 0.33–0.35 g (5.1–5.4 gr) in weight, usually zinc- or copper-plated for corrosion resistance. Some manufacturers still make the slightly larger traditional lead balls that weigh around 0.48–0.50 g (7.4–7.7 gr), which are generally intended for use in rifled barrels.

Wadcutter

A wadcutter is a special-purpose flat-fronted bullet specifically designed for shooting paper targets, usually at close range and at subsonic velocities typically under approximately 900 ft/s (274 m/s). Wadcutters have also found favor for use in self-defense guns, such as .38 caliber snubnosed revolvers, where, due to short barrel lengths, maximum bullet velocities are usually low, typically under 900 ft/s (274 m/s), and improved lethality is desired. Wadcutters are often used in handgun and airgun competitions.

Gun barrel Firearm component which guides the projectile during acceleration

A gun barrel is a crucial part of gun-type ranged 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-pressure gas(es) is used to propel a projectile out of the front end (muzzle) at a high velocity. The hollow interior of the barrel is called the bore, and the diameter of the bore is called its caliber, usually measured in inches or millimetres.

Internal ballistics, a subfield of ballistics, is the study of the propulsion of a projectile.

A slug is a term used for a bulky solid ballistic projectile. It is "solid" in the sense of being composed of one piece; the shape can vary widely, including partially hollowed shapes. The term is occasionally applied to bullets, but is most commonly applied to one-piece shotgun projectiles, to differentiate them from shotshells containing shots. Slugs are commonly fired from choked smoothbore barrels, but some specially-designed slug barrels have riflings that can impart gyroscopic spin required for in-flight stability.

Shotgun shell Self-contained cartridge loaded with lead shot or a solid slug

A shotgun shell, shotshell or simply shell is a type of rimmed, cylindrical (straight-walled) cartridges used specifically by shotguns, and is typically loaded with numerous small, pellet-like spherical sub-projectiles called shots, fired through a smoothbore barrel with a tapered constriction at the muzzle to regulate the extent of scattering. A shell can sometimes also contain only a single large solid projectile known as a slug, fired usually through a rifled slug barrel. The shell casing usually consist of a paper or plastic tube mounted on a brass base holding a primer, and the shots are typically contained by a wadding/sabot inside the case. The caliber of the shotshell is known as its gauge.

Accurizing Process of improving the accuracy and precision of a gun

Accurizing is the process of improving the accuracy and precision of a gun.

Shotgun slug Type of ammunition used mainly in hunting game

A modern shotgun slug is a heavy projectile made of lead, copper, or other material and fired from a shotgun. Slugs are designed for hunting large game, self-defense, and other uses. The first effective modern shotgun slug was introduced by Wilhelm Brenneke in 1898, and his design remains in use today. Most shotgun slugs are designed to be fired through a cylinder bore or an improved cylinder choke, rifled choke tubes, or fully rifled bores. Slugs differ from round-ball lead projectiles in that they are stabilized in some manner.

In the field of firearms and airguns, obturation denotes necessary barrel blockage or fit by a deformed soft projectile. A bullet or pellet, made of soft material and often with a concave base, will flare under the heat and pressure of firing, filling the bore and engaging the barrel's rifling. The mechanism by which an undersized soft-metal projectile enlarges to fill the barrel is, for hollow-base bullets, expansion from gas pressure within the base cavity and, for solid-base bullets, "upsetting"—the combined shortening and thickening that occurs when a malleable metal object is struck forcibly at one end.

A rifled musket, rifle musket, or rifle-musket is a type of firearm made in the mid-19th century. Originally the term referred only to muskets that had been produced as a smoothbore weapon and later had their barrels replaced with rifled barrels. The term later included rifles that directly replaced, and were of the same design overall as, a particular model of smoothbore musket.

Gauge (firearms) Bore diameter

The gauge of a firearm is a unit of measurement used to express the inner diameter of the barrel.

ISSF 10 meter air rifle International Shooting Sports Federation shooting event

10 metre air rifle is an International Shooting Sports Federation (ISSF) shooting event, shot over a distance of 10 metres from a standing position with a 4.5 mm (0.177 in) calibre air rifle with a maximum weight of 5.5 kg (12.13 lb). The use of specialized clothing is allowed to improve the stability of the shooting position and prevent chronic back injury which can be caused by the asymmetric offset load on the spine when the rifle is held in position. It is one of the ISSF-governed shooting events included in the Olympic games.

Daisy Outdoor Products Air gun manufacturer

Daisy Outdoor Products is an American airgun manufacturer known particularly for their lines of BB guns. It was formed in 1882 initially as the Plymouth Iron Windmill Company to manufacture steel windmills, and from 1888 started bundling BB-caliber air guns with each windmill purchase as a sales promotion. With the unrivaled popularity of their 1888-model Daisy BB Guns, the company changed the name to Daisy Manufacturing Company in 1895 and switched their business to solely producing air guns for sale. Throughout the 20th century, Daisy has been known as a company that makes and sells BB guns and pellet youth rifles. Their Red Ryder BB Gun is perhaps the best known and longest production item, which has been featured in many TV shows and movies since its introduction in the 1930s.

Choke (firearms)

In firearms, a choke is a tapered constriction of a gun barrel at the muzzle end. Chokes are most commonly seen on shotguns, but are also used on some rifles, pistols, or even airguns. Notably, some .22 LR match rifles have a constricted bore diameter near the muzzle.

References

  1. House, Jim. "HUNTING WITH AIRGUNS Ch.6". crosman.com. Crosman. Retrieved 10 December 2014.
  2. "About Pellet Numbers and Pellet Testing". Vogel USA. Archived from the original on 2012-05-04. Retrieved 2012-05-01.
  3. Air Gun Testing Target Pellets
  4. Scott Pilkington (May–June 2008). "About Pellet Numbers and Pellet Testing" (PDF). USA Shooting News. Retrieved 2013-02-20.
  5. Haendler & Natermann Finale Match Rifle