Pellet (air gun)
Encyclopedia
An air gun pellet is, for the most part, a non-spherical projectile designed to be fired from an air gun
. But this is not always the case.
Pellets differ from bullet
s used in firearm
s because of the pressure
s encountered; firearms operate at pressures of thousands of atmospheres
, while airguns operate at pressures as low as 50 atmospheres. Firearms have sufficient pressure to force a slightly over-sized bullet to fit the bore in order to form a tight seal, while airguns generally use a slightly undersized projectile that is designed to obturate
upon shooting so as to seal the bore, and engage the rifling
. 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.
The "diabolo," sometimes called wasp waist pellet is the most common design found today.
The diabolo pellet can have a flat, round, hollow or pointed tip, followed by a taper to a thin waist
. From the waist back, the pellet is hollow, and flares out to full diameter when pressurized by the gun. The head, or solid part in front of the waist, is usually sized to fit the bore
just touching the rifling
. This keeps the pellet centred 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 as air as is inherently possible. The skirt of the pellet is thin, and made of a malleable material, usually lead
, although non-toxic alternatives are available that use tin
or even plastic. When shot, the skirt will obturate to fit the bore and provide a good seal, and engage 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. In most cases of this type, the solid head in the front and hollow skirt in back will work to prevent the pellet from tumbling. However, this is not always the case, and some ammo types of this nature will tumble in flight, and keyhole the target. When this happens the pellet will not leave a clean, round hole in the paper, but will instead, leave behind a keyhole shaped silhouette.
Pellets are, by their very nature, 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 break-barrel and PCP air rifles, which often can push a normal pellet to velocities exceeding the speed of sound. A few companies have addressed this issue by manufacturing heavier than normal pellets for use in these high powered air guns. The heavier weight of these pellets ensure that they will travel at speeds well below the sound barrier, resulting in less tumbling and more overall accuracy. Their weight also makes them less susceptible to air resistance, and thus imparts more kinetic energy downrange, increasing lethality.
_match_air_gun_pellet.jpg)
Match pellets are used for the 10 metre air rifle and 10 metre air pistol disciplines. These 4.5 mm (.177 in) caliber pellets have what is known as wadcutter
heads, meaning the front is (nearly) flat, that leave clean 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 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. 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 up to 4.52 mm.
Air gun
An air gun is a rifle , pistol , or shotgun that fires projectiles by means of compressed air or other gas, in contrast to a firearm, which burns a propellant. Most air guns use metallic projectiles as ammunition. Air guns that only use plastic projectiles are classified as airsoft...
. But this is not always the case.
Pellets differ from bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
s used in firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
s because of the pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
s encountered; firearms operate at pressures of thousands of atmospheres
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
, while airguns operate at pressures as low as 50 atmospheres. Firearms have sufficient pressure to force a slightly over-sized bullet to fit the bore in order to form a tight seal, while airguns generally use a slightly undersized projectile that is designed to obturate
Obturate
Obturate means to block or obstruct. With reference to firearms and airguns, obturation refers to the process of a bullet or pellet, made of soft material and often with a concave base, flaring under the pressure of firing to seal the bore and engage the barrel's rifling...
upon shooting so as to seal the bore, and engage the rifling
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...
. Since pellets may be shot through a smoothbore
Smoothbore
A smoothbore weapon is one which has a barrel without rifling. Smoothbores range from handheld firearms to powerful tank guns and large artillery mortars.-History of firearms and rifling:...
barrel
Gun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....
, they are often designed to be inherently stable, much like the Foster slugs used in smoothbore shotguns.
The "diabolo," sometimes called wasp waist pellet is the most common design found today.
The diabolo pellet can have a flat, round, hollow or pointed tip, followed by a taper to a thin waist
Waist
The waist is the part of the abdomen between the rib cage and hips. On proportionate people, the waist is the narrowest part of the torso....
. From the waist back, the pellet is hollow, and flares out to full diameter when pressurized by the gun. The head, or solid part in front of the waist, is usually sized to fit the bore
Caliber
In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....
just touching the rifling
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...
. This keeps the pellet centred 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 as air as is inherently possible. The skirt of the pellet is thin, and made of a malleable material, usually lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, although non-toxic alternatives are available that use tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
or even plastic. When shot, the skirt will obturate to fit the bore and provide a good seal, and engage 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. In most cases of this type, the solid head in the front and hollow skirt in back will work to prevent the pellet from tumbling. However, this is not always the case, and some ammo types of this nature will tumble in flight, and keyhole the target. When this happens the pellet will not leave a clean, round hole in the paper, but will instead, leave behind a keyhole shaped silhouette.
Pellets are, by their very nature, 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 break-barrel and PCP air rifles, which often can push a normal pellet to velocities exceeding the speed of sound. A few companies have addressed this issue by manufacturing heavier than normal pellets for use in these high powered air guns. The heavier weight of these pellets ensure that they will travel at speeds well below the sound barrier, resulting in less tumbling and more overall accuracy. Their weight also makes them less susceptible to air resistance, and thus imparts more kinetic energy downrange, increasing lethality.
Match shooting use
Wadcutter
A wadcutter is a special-purpose bullet specially designed for shooting paper targets, usually at close range and at subsonic velocities typically under 800 ft/s . They are often used in handgun and airgun competitions...
heads, meaning the front is (nearly) flat, that leave clean 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 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. 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 up to 4.52 mm.