What is Airsoft??
Airsoft is a military simulation sport in which players participate in mock combat with military-style mock weapons and tactics. Airsoft guns usually use 6 mm spherical pellets typically made of solid plastic.
Airsoft refers to a class of replica air powered guns that originated from Japan (although the origins go back to the US in the 70s). The power levels are way below those of traditional airguns, but the guns are 1:1 scale copies of original pistols, rather than original designs.
Airsoft guns
The guns used in airsoft are typically replicas of real firearms. Airsoft guns can be divided into three groups by what powers them: spring powered, electric powered, and gas-powered.
Spring powered
Spring-powered airsoft guns (often called "springers" or "spring guns") are single-shot devices that use potential energy stored in a spring to launch an airsoft pellet down the barrel of the gun. The user must cock a spring gun prior to each shot much like you would a real shotgun or bolt-action rifle. This is typically achieved by pulling back the slide (pistols) or bolt (rifles), which in turn compresses the spring and makes the gun ready to fire. Because of this these guns are incapable of automatic or semi-automatic fire.
While most electric guns also use springs for this they are not considered to be in the same category as the single-shot spring-powered guns. Low-end spring guns tend to be much cheaper than their electric-powered equivalents due to their simplicity and cost of components (spring assembly vs. spring assembly, electric motor, battery, and battery charger) and thus are widely available. These guns are less suited for competition because they are at a disadvantage against automatic guns in close combat and don't provide enough accuracy and power for long-range uses. Higher-end spring-powered airsoft rifles can be quite expensive; these guns are typically suited for "sniper" applications in airsoft matches and can provide competitive muzzle velocities.
Electric powered
Electric-powered airsoft guns typically use a bank of rechargeable batteries to drive an electric motor, which cycles an internal piston/spring assembly in order to launch pellets. Automatic and semi-automatic operation is possible which gives these guns the popular name "automatic electric guns" or AEG's. These guns often attain muzzle velocities of 200 to 300 feet per second (60 to 90 m/s) and fire rates of 300 to 700 rounds per minute and are by far the most common and widely available airsoft guns in serious competition use today.
These guns were originally developed in Japan, and the Japanese model giant Tokyo Marui dominates the market today with many quality models. In a Marui AEG, the motor drives a series of 3 gears mounted inside a gearbox. The gears then compress a piston assembly against a spring. Once the piston is released, the spring drives it forward through the cylinder to push a pellet into the chamber, through the barrel, and forward from the muzzle. Many manufacturers have now more or less replicated this basic model, adding reinforced parts or minor improvements.
Gas powered
Gas-powered airsoft guns use pressurized gas to propel pellets. These guns are capable of automatic and semi-automatic operation. The most common gases used are propane (usually referred to as "green gas" by airsoft players) and HFC134a refrigerant. Less commonly used gases include CO2 and nitrogen.
Gas power tends to be used in airsoft pistols where size constraints make electric-powered mechanisms impractical. Other instances where gas is favored are where adjustable velocities are required or where a blow-back feature is desired. A blow-back feature is a mechanism which cycles a slide or bolt to better simulate a real firearm's operation. Because of the mechanical complexities involved with distributing and regulating gas these guns have largely given way to electric guns for less specialized applications.