Calibers
The most common air gun calibers are:
- .177 (4.5 mm): the most common caliber, also used in ISSF shooting events at the Olympic Games, it has the flattest trajectory of all the calibers for a given energy level, making accuracy simpler. As well as its very effective targetry use, this caliber can be effectively used to hunt small quarry or vermin.
- .20 (5.0 mm): found in some European air guns and those manufactured by the American air gun manufacturer Sheridan. This is generally considered to be a "compromise caliber", having a flatter trajectory similar to the .177 but more energy retention. .20" pellets tend to be of a similar weight to .22" pellets, but with an elongated profile, resulting in a higher Ballistic Coefficient (BC) than either .177 or .22 pellets.
- .22 (5.5 mm & 5.6 mm): the most common caliber for hunting small game, as it delivers large amounts of energy on impact.
- .25 (6.35 mm): the largest commonly available caliber. This caliber is renowned for its impact, having the most energy retention of all calibers. It does have a highly parabolic trajectory at low energy levels and is thus more suited for higher powered rifles.
- .357 Found in certain new crosman PCP airguns.
Custom air gun manufacturers regularly produce air rifles in common muzzle loading calibers, such as .45 (11.43 mm), .50 (12.7 mm), .58 (14.5 mm); some recently built custom air guns are even larger, 20 mm (0.79") or .87 (22.1 mm).
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