An air gun is a pneumatic gun which fires projectiles using compressed air or other high pressure gas as a propellant.
Air guns represent the oldest pneumatic technology, having existed since the 15th century. At that time, they presented compelling advantages over the more primitive firearms of the day. For example, air guns could be fired in wet weather (unlike matchlocks) and with greater rapidity than the muzzle-loading guns of the period. Moreover, they were quieter than a firearm of similar caliber, had no muzzle flash and were completely smokeless, not disclosing the shooter`s position on firing. Black powder guns of the 18th and 19th century produced huge volumes of dense smoke on firing, giving air rifles an advantage over them. One might also assume that the sound of an air gun would have been inaudible against the noise of a pitched battle.
For general usage air guns were not a real challenge to the dominant position of powder weapons. They were expensive, delicate, air reservoirs could burst explosively and the valves were not well sealed and slowly leaked pressure. Historical accounts mention common soldiers were often unable to handle the complex guns, this seems logical in an age where the average peasant recruit had never encountered a machine more complex than a horse-drawn cart. People who had any experience with mechanical devices (millers or clockmakers) were few and far between. The guns of the period were crude and required little skill by the infantryman.
During this period, France, Austria and other nations had special sniper detachments using air rifles. The Austrian 1780 model was named "Windbüchse" (literally "wind rifle") in German. The guns were developed in 1778 or 1779 by the Tyrolese watchmaker, mechanic and gunsmith Bartholomäus Girandoni (1744-1799) and are occasionally referred to as "Girandoni air guns" in literature (the name is occasionally spelled "Girandony"; "Giradoni" or "Girardoni". The Windbüchse (or the Girandoni Air Rifle) 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 of the time. The air reservoir was a removable, club-shaped butt. The Windbüchse carried twenty .51" (13 mm) lead balls in a tubular magazine. A skilled shooter could unload one magazine in about thirty seconds, which was a fearsome rate of fire compared to the slower muzzle loaders of the period. 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 9 mm or .45" caliber pistol.
Air gun developed by the Japanese inventor Kunitomo, circa 1820-1830.
Kunitomo air gun trigger mechanism.Around 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") acquired from the Dutch in Dejima.
Air guns appear throughout other periods of history. The celebrated expedition headed by Lewis and Clark (1804) reportedly carried a .42" (10 mm) reservoir air gun, believed to be produced by Girandoni. It held 22 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. The rifle was said to be capable of 22 aimed shots in one minute.
During the 1890s, air rifles were used in Birmingham, England for competitive target shooting. Competitions were held in, and between, public houses. Prizes, such as a leg of mutton for the winning team, were paid for by the losing team. The sport became so popular that just after the turn of the 19th century, a National Air Rifle Association was created. During this time over 4000 air rifle clubs and associations existed across Britain, many of them in Birmingham.
During this time, the air gun was associated with poaching because it could deliver a shot at a relatively quiet level. A modern reproduction of an air cane copied accurately from one in the Royal Armouries, Leeds, UK by Baker and Currie gives a performance of around 480 feet per second (ft/s) for a 51.5 grain 32 calibre lead ball. The reproduction was charged to 600 pounds per square inch and the first shot registered only 272 ft/s, indicating this is a realistic maximum pressure given that the release valve failed to open properly against the high pressure of air in the reservoir. The velocities were reasonably constant for the next five shots, after which they progressively diminished by about 20 ft/s per shot, though this figure is not exact. In an experimental simple home-made large calibre air gun with a three metre barrel Middleton obtained a maximum velocity of 599 ft/s for a 50 calibre 140 grain lead ball, and 411 ft/s from a 2 metre barrel with a .527 calibre 220 grain lead ball, using a pressure of only 100 pounds per square inch pumped with a bicycle pump. Reilly, a London gunmaker specialising in air guns, writing around 1850 states that he was able to produce a pressure of a little under 500 pounds per square inch using the direct stroke pump of the time. He does not give muzzle velocities. Wesley (op.cit., pp. 35-6) shot an antique air cane bullet of 3/4 inch diameter into the cast iron fireplace of his workroom, and demolished the fireplace, stripped the wallpaper off the walls, and blew all his oils and chemicals off the mantleshelf.
Today`s modern air guns are typically low-powered because of safety concerns and legal restrictions; however, 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 of sound and produce a noise similar to a .22 caliber rimfire rifle. Using very light plastic or alloy pellets, many current spring powered .177 pellet guns can break the sound barrier, and one, the Gamo 1250, can reach 1600 fps with these new pellets. Most low-powered airguns can be safely fired in a backyard or garden, and even indoors, with the 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 events at the Olympic Games, governed by the International Shooting Sport Federation (ISSF).