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Air rifle was developed at the United States is experiencing a war of independence against England. Also developed further during the American civil war turmoil. At that moment a pellet gun can kill a calf / calves in the range of 10 meters is head. Regarding the firing range, depending on the type of pellet gun. For the type of spring has an effective range of 30 to 40 meters (depending on material and quality of spring), for the type of pump is the effective range of 40 meters (depending on the pumping strength) and type of gas has an effective range of 60 meters.
In the 17th century, air guns, in caliber .30–.51, were used to hunt big game deer and wild boar. These air
rifles were charged using a pump to fill an air reservoir and gave
velocities from 650 to 1,000 feet per second (200–300 m/s). They were
also used in warfare.
At that time, they had compelling advantages over the primitive
firearms of the day. For example, air guns could be fired in wet weather
and rain and with greater rapidity than muzzle loading guns.
Moreover, they were quieter than a firearm of similar caliber, had no
muzzle flash, and were completely smokeless, thus not disclosing the
shooter's position or obscuring his view. Black powder muskets of the
18th and 19th century produced huge volumes of dense smoke when fired, a
disadvantage compared to air rifles.
Although some enthusiasts suggest air guns posed a serious
alternative to powder weapons, that was never proved to be the case, as
valve leaks and bursting reservoirs were known problems. Air guns also
were delicate, and peasant-soldiers, many of whom had never seen any
mechanical tools more complex than horse-drawn carriages, could not have
operated or maintained them properly.
Later improvements in valve designs and reservoir strength either came
too late or were too complex for the few air gunsmiths of the day.
But in the hands of skilled soldiers, they gave the military a distinct
advantage. France, Austria, Japan and other nations had special sniper detachments using air rifles. The Austrian 1780 model was named Windbüchse (literally "wind rifle" in German). The gun was developed in 1778 or 1779 by the Tyrolese watchmaker, mechanic and gunsmith Barolomaus Girardoni (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 4 ft (1.2 m) long and weighed 10 pounds (4.5 kg), which was
about the same size and mass as a conventional musket. The air reservoir
was a removable, club-shaped butt. The Windbüchse carried twenty-two .51 in (13 mm) lead balls in a tubular magazine.
A skilled shooter could fire off one magazine in about thirty seconds,
which was a fearsome rate of fire compared to a muzzle loader. A shot
from this air gun could penetrate a one-inch wooden board at a hundred
paces, an effect roughly equal to that of a modern 9mm or .45 ACP caliber pistol.
Around 1820, the Japanese inventor Kunitomo Ikk developed various manufacturing methods for guns, and also created an air gun based on the study of Western knowledge ("rangaku") acquired from the Dutch in Dejima
Air guns appear throughout other periods of history. The celebrated Lewsi and Clark Expedition (1804) carried a reservoir air gun, later believed to be the Girandoni Repeating Air Riffle in Dr Robert Beeman's Collection. It held 22 .46 calibre round balls in a tubular magazine mounted on the side of the barrel.
The butt stock served as the air reservoir and had a working pressure
of 800 psi (5,500 kPa). The rifle was said to be capable of 22 aimed
shots in 1 minute. That air rifle is measured to have a rifled bore of
0.452 in (11.5 mm) and a groove diameter 0.462 in (11.7 mm).
During the 1890s, air rifles were used in Birmingham, England, for competitive target shootinh. Matches were held in public house, which sponsored shooting teams. Prizes, such as a leg of mutton for the winning team, were paid for by the losing team. The sport became so popular that in 1899, the National Smallbore Riffle Association was created. During this time over 4,000 air rifle clubs and associations existed across Great Britain, many of them in Birmingham. During this time, the air gun was associated with poachingbecause it could deliver a shot without a significant report.
Today's modern air guns are typically low-powered because of safety
concerns and legal restrictions. High-powered designs are still used for hunting. These air rifles can propel a pellet beyond 1100 ft/s (330 m/s), approximately the speed sound, and produce a noise similar to a 22 caliber rim fire riffle.
Using lead pellets, some current spring powered .177 pellet guns can
break the sound barrier. Most low-powered air guns can be safely fired
in a backyard or garden, and even indoors, with a proper backstop.
In some countries, air guns are still classified as firearms, and as
such it may be illegal to discharge them in residential areas. Air guns
can be highly accurate and are used in target shooting event at the Olympic Game, governed by the International Shooting Sport Federation (ISSF), where they are shot at a range of 10 m or 32.8 feet.
USE
Air guns are used for hunting, pest control, recreational shooting (commonly known as plingking), and competitive sports, such as the Olympic 10 m Riffle and 10 m air pistol events. Field Target
(FT) is a competitive form of target shooting in which the targets are
knock-down metal silhouettes of animals, with a 'kill zone' cut out of
the steel plate. 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
10 and 50 metres (33 and 160 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. 12 ft lbf (16 J).
POWER
There are different methods of powering an air gun. These methods can be
broadly divided into 3 groups: spring-piston, pneumatic, and CO2. These methods are used in both air rifles and air pistols.
Spring Piston
Spring-piston air guns are able to achieve muzzle velocities near or greater than the speed sound
from a single stroke of a cocking lever or the barrel itself. The
difficulty of the cocking stroke is usually related to the power of the
gun, with higher muzzle velocities requiring greater effort.
Spring-piston guns operate by means of a coiled steel spring-loaded piston
contained within a compression chamber, and separate from the barrel.
Cocking the gun causes the piston assembly to compress the spring until a
small hook on the rear of the piston engages the sear;
pulling the trigger releases the sear and allows the spring to
decompress, pushing the piston forward, thereby compressing the air in
the chamber directly behind the pellet. Once the air pressure has risen
enough to overcome any static friction and/or barrel restriction holding
the pellet, the pellet moves forward, propelled by an expanding column
of 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.
Spring-piston guns have a practical upper limit of 1250 ft/s
(380 m/s) for .177 cal (4.5 mm) pellets. Higher velocities cause
unstable pellet flight and loss of accuracy. This is due to the shocwave
generated as the super sonic pellet contacts the air. Shortly after
leaving the barrel, the pellet falls below the speed of sound and the
shock wave overtakes the pellet, causing it to tumble. 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 and drawing unwanted attention.
Many shooters have found that velocities in the 800–900 ft/s (240–270
m/s) range offer an ideal balance between power and pellet stability.
Most spring piston guns are single-shot breech-loaders by nature, but
multiple-shot guns have become more common in recent years. Spring guns
are typically cocked by a mechanism requiring the gun to be hinged at
the mid-point (called a break barrel), with the barrel serving as a
cocking lever. Other systems that are used include side levers,
under-barrel levers, and motorized cocking, powered by a rechargeable
battery.
Spring guns, especially high-powered ones, have significant recoil
resulting from the forward motion of the piston. Although this recoil is
less than that of a cartridge firearm, it can make the gun difficult to
shoot accurately as the recoil forces are well under way while the
pellet is still traveling down the barrel. Most guns seem to respond
well to a light, repeatable grip that allows the gun to vibrate the same
way from shot to shot. This method is commonly referred to as the
"artillery hold", in reference to the way large military artillery pieces like the M777 howitzer
often recoil. Spring gun recoil also has a sharp forward component,
caused by the piston as it hits the forward end of the chamber when the
spring behind it reaches full expansion. This sudden forward
acceleration helps to counteract the recoil, since the recoil and
"forward recoil" forces happen within milliseconds of each other, but it
is infamous for the loosening or breaking of lenses and reticles found
in low- and medium-priced telescopic sight. All mounted telescopic sights for air guns should be rated as such.
Spring guns can also suffer from spring vibrations that reduce
accuracy. 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
modification is the addition of viscous silicone grease to the spring,
which both lubricates it and dampens vibration.
The better quality spring air guns can have very long service lives,
being simple to maintain and repair. Because they deliver the same
energy on each shot, their trajectory is consistent. Most Olympic
air gun matches 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 began to dominate competition. Today, the guns used at
the highest levels of competition are powered by compressed air stored
at very high pressures of 2000 to 3000 psi 14 to 21 MPa
Gas Spring
Some makes of air rifle (e.g. Weihrauch, Theoben) incorporate a gas spring
in some models instead of a mechanical spring. Pressurized air or
nitrogen is held in a chamber built into the piston, and this air is
further pressurized when the gun is cocked. It is, in effect, a gas
spring commonly referred to as a "gas ram" or "gas strut". Gas spring
units require higher precision to build, since they require a low
friction sliding seal that can withstand the high pressures when cocked.
Gas spring units are available as an upgrade for some popular models
such as the Weirauch HW80, the Crosman 766C American Classic air rifle
and the Arowsmith 876 Magnum rifle. The advantages of the gas spring
include the facility to keep the rifle cocked and ready to fire for long
periods of time without harming the mechanism. Also, since there is no
spring (and therefore a reduction in moving mass during firing) there is
less (although some say slightly sharper) recoil. There is also an
elimination of the associated problems of long-term spring fatigue and a
faster "lock time" (the time between pulling the trigger and the pellet
being discharged). The improvement in lock time makes for better
accuracy since there is less time for the gun to move off target.
Finally, gas springs are practically maintenance free and last longer
than conventional metal springs (research test ch1208); they are an
order of magnitude more expensive when they do need replacement.
Pneumatic
Pneumatic air guns utilize precompressed air as the source of energy to
propel the projectile. Single-stroke and multy-stroke guns utilize an
on board pump to pressurize the air in their reservoir, Precharged
Pneumatic guns' reservoirs are filled using either a high-pressure hand
pump (often capable of attaining pressures of 30 MPa) or by decanting
the necessary volume/pressure of air from a diving cylinder. Because of
this design, having no significant movement of heavy mechanical parts
during the firing cycle, the recoil produced is only the 'true' recoil,
equivalent to the equal and opposite reaction to the pellet and air
volume's acceleration up the bore.
Multi Stroke
Multy Stroke pneumatic air guns require 2–10 pumps of an on-board
lever to store compressed air within the air gun. Variable power can be
achieved through this process, as the user can adapt the power level for
long, or short-range shooting. The design of higher quality and
match-grade multy-stroke air rifles can propel a pellet to speeds in
excess of 1,000 feet per second (300 m/s).
For beginners and intermediates, multy-stroke air rifles have been a
cost-effective choice as they are generally the cheapest form of air gun
available. Several manufacturers make multi-stroke air guns including,
to name a few, Sheridan, Benjamin, Daisy, and Crossman.
Modified multy-pump guns, with stronger pump linkages and improved
valves, can produce muzzle energies in excess of 30 foot-pounds force
(41 J)
Single Stroke
As the name implies, one motion of the cocking lever is all that is
needed to compress the air for propulsion. The single-pump system 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 internationa 10 metre air riffle shooting event rom the 1970s up to the 1990s.
Pre-Charge Pneumatic
Pre-charged pneumatic (PCP) air guns are usually filled by decanting from an air reservoir, such as a diving cylinder
or by charging directly with a hand pump. Because of the need for
cylinders or charging systems, PCP guns have higher initial costs but
very low operating costs compared to CO2 guns. These guns are
often used for hunting purposes in countries with restrictive firearms
laws. A distinction is sometimes made between true PCP guns and high
pressure air (HPA) guns. The distinction being that true PCP guns are an
integrated high pressure design while an HPA application is an
adaptation of a high pressure, regulated air supply to function with
components not designed for high pressure CO2 guns. The RWS/Hammerli 850 is a CO2 designed gun, which is often adapted to HPA.
PCP guns have very low recoil and can fire as many as 500 shots per
charge. The ready supply of air has allowed the development of
semi-automatic and fully automatic
PCP air guns. PCP guns are very popular in the UK and Europe because of
their accuracy and ease of shooting. They are widely utilized in ISSF 10 metre air riffle and pistol event and the sport of field target shooting, and fitted with telescopic sight.
Earlier hand pumps for charging carried with them problems of fatigue
(both human and mechanical), temperature warping, and condensation.
None of those is beneficial to good shooting or the longevity of the
rifle. Modern hand pumps have built-in air filtration systems and have
overcome many of these problems. Using scuba-quality air decanted from a scuba cylinder also provides a clean, dry, high-pressure air supply that is consistent and available at low cost.
During the typical PCP's discharge cycle, the hammer of the rifle is
released by the sear to strike the valve. The hammer may move rearwards
or forwards, unlike firearms where the hammer almost always moves
forward. Prior to being struck by the hammer, 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 decreases with
each successive shot. As a result, when the reservoir pressure is at its
peak, 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
self-regulation that gives a greater consistency of velocity from shot
to shot than would otherwise be expected. A well-designed PCP will
display good self-regulation properties, meaning good shot to shot
consistency over a range of pressures as the air reservoir is
diminished.
More expensive PCP rifles and pistols are often pressure regulated,
i.e. the firing valve operates within a secondary chamber separated from
the main air reservoir by the regulator body. The regulator maintains
pressure within this secondary chamber at a set pressure lower than the
main reservoir's. This occurs until the main reservoir's pressure is
diminished to the set pressure, after which the PCP behaves in an
unregulated manner. Thus shot to shot consistency is maintained for
longer than in an unregulated rifle, at the expense of efficiency, shots
per fill and often at a lower velocity.
Carbon Dioxide CO2
Most CO2 guns (e.g.Baretta Elite II) use a disposable cylinder, a powerlet, that is purchased often pre-filled with 12 grams of pressurized carbon dioxide, although some, usually more expensive models, use larger refillable CO2 reservoirs like those typically used with paintball marker
Carbon dioxide-powered guns have two significant advantages over pre-charged pneumatic air guns:
- A simpler system for compact storage of energy—a small volume of liquid converts to a large volume of pressurized gas.
- No pressure regulator. Within a temperature range tolerable to humans there is little need to regulate the inherently suitable pressure for low-to-moderate-power air guns. The vapor pressure is dependent only on temperature, not tank size, as long as some liquid CO2 remains in the reservoir.
These two advantages allow CO2 guns to be constructed more simply than guns using a pressurized air reservoir. Some CO2-powered guns have detachable or fixed reservoirs that are loaded with pressurized gas from a larger cylinder. Most CO2
powered guns use the standard 12 gram Powerlet disposable cylinder
invented by Crosman. Recently, the same company introduced a new 88 gram
disposable AirSource cylinder that is used in some of their guns.
On the other hand, liquefied CO2 must be purchased, which
introduces an element of cost that does not factor with a PCP gun/hand
pump combination using "free" air, or is at least considerably lower
when refilling from a diver's tank.
Furthermore, the pressure of gaseous CO2 at ordinary
ambient temperatures is only around 850–1000 psi (6 to 7 MPa), which is
only a third of the safe working pressure of a typical full PCP
reservoir (20 MPa or 2900 psi or more). The effect of this is that
generally speaking CO2 guns are lower powered and less efficient than PCP guns, which is why CO2
guns are usually pistols or semi-target type rifles, with few guns
(none of commercial note) reaching even the 12 ft·lbf (16 J)
licence-free energy limit for air rifles imposed in the UK.
CO2 guns, like compressed air guns, offer power for
repeated shots in a compact package without the need for complex cocking
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. These guns are popular for training, as the guns and ammunition
are inexpensive, 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, although there are still a few precision target guns on the market that use CO2.
The CO2 system has been used in experimental non-lethal
law enforcement weapons, where high power delivery systems launch rubber
batons or bean bag out of a gas-powered launcher, much like a non-lethal shotgun system (but at lower velocities, thus being safer).
Safety
For safety, CO2 containers must be kept at temperatures below
120 °F (49 °C) ; at temperatures above this level, the pressure begins
to increase very rapidly, and can cause the container to fail. CO2
containers with diameters at or above two inches (50 mm) have a
pressure release "rupture" mechanism to release the contents over a
certain pressure level and avoid explosion because of high temperature.
These disks are generally calibrated to a minimum pressure corresponding
to the 120 °F (49 °C) level at 100% of the rated CO2 capacity. Elevated temperatures, even those below the critical temperature, can cause increased leaking through seals
Re-filling Forcing more carbon dioxide gas into a reservoir of liquid and gas CO2
while maintaining a constant temperature would not raise the pressure
but merely convert the additional gas into liquid. By chilling the
vessel to be filled, the lower vapor pressure will pull CO2
from the source container. While the pressure in the reservoir is
generally dependent only on the temperature, if the bottle is too full,
that changes. The expansion of the liquid CO2 will take up
all the space in the bottle, preventing
Cooling Each time the gun is fired there is rapid evaporation of liquid to gas, which is an endothermic
process in which the pressure drops until enough ambient heat is
absorbed to restore the pressure. When shooting at a rate faster than
the cylinder can absorb heat from the environment to counter the cooling
of the evaporating liquid, the pressure will drop, and the velocity is
likely to drop as well in a non-regulated gun.
Pellet
The most popular ammunition used in rifled air guns is the lead
diabolo pellet. This waisted projectile is hollowed at the base and
available in a variety of head styles. The diabolo pellet is designed to
be drag stabilized, though is not as stable as some other shapes in the transonic region
(272–408 m/s ~ 893–1340 ft/s). Pellets are also manufactured from tin,
or a combination of materials such as steel-tipped plastic.
Most air guns are .177 (4.5 mm) or .22 (5.5 mm / 5.6 mm), and are
designed for target practice, small game hunting and field target
shooting. Cost per round is less than $0.02 (US) for Olympic-quality
ammunition, and far less for cheaper grades. Though less common, .20 and
.25 caliber (5.0 mm and 6.4 mm) guns also exist and are used predominantly for hunting.
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