Airguns - that is air rifles and air pistols - differ from the other guns that we shoot, as they do not use any explosive substances in order to expel their pellets.

Air weapons are based on the principle of the blowgun: shooting bullets, pellets or darts by the use of compressed air.

Rather than using a bullet fired from a case, the air gun uses a pellet of lead which is 'blown out' of the barrel by air compressed by a coiled spring, or by gas compressed within a cylinder - e.g. CO2.

Early air weapons worked by using a reservoir of compressed air. When this was suddenly released by a trigger it then projected a shot, albeit with limited accuracy and range.

In the 16th century, a spring was used in place of the reservoir of air, with the release of the spring by the trigger, the spring then moved a piston, which in turn compressed air that forced the shot through the bore of the gun.

This principle is still used in many air rifles or air pistols, though there is also the alternative of using a cylinder of compressed gas to power the pellet.

These use the older 'reservoir' concept, either by filling a reservoir with compressed gas or by using small disposable cylinders of compressed gas - usually carbon dioxide.

The NSRA is the national governing body of airgun shooting.

Air weapons are exempt from Firearms Certification, but must not exceed 6 foot pounds in the case of an air pistol, or 12 foot pounds in the case of anything other than an air pistol.

If an air rifle exceeds this then it must be held on a Firearms Certificate.