20 mm caliber

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The 20 mm caliber is a specific size of cannon or autocannon ammunition, commonly the smallest caliber which is unambiguously a cannon (or more commonly today, autocannon) and not a heavy machine gun.

There are relatively few weapons which have been built which fire projectiles between .50 caliber (0.50 inch/12.7 mm, roughly 12 mm caliber) and 20 mm caliber, though the 14.5 mm caliber was used by some Soviet machineguns such as the KPV and antitank rifles such as PTRS and PTRD.

A very small number of anti-tank rifles have been produced in 20 mm and up calibers.

20 mm caliber cartridges have an outside shell diameter and inside barrel diameter of 0.8 inch (20 millimeters). Projectiles or shells are typically 3 to 4 inches long (76 to 104 mm). Cartridges are typically 3 to 5 inches long (76 to 127 mm). Many but not all 20 mm shells have an explosive filling and detonating fuze.

As an example, the 20x102 has a 100 gram bullet fired at a muzzle velocity of 1,035 m/s. For a simple slug round this is a muzzle energy of 53,600 joules or 39,500 ft·lbf.

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[edit] Usage

20 mm with .50 BMG rounds, golf ball, stick of RAM.
20 mm with .50 BMG rounds, golf ball, stick of RAM.

Like most cannon ammunition, 20 mm caliber weapons are typically used against large targets such as vehicles, buildings, or aircraft. Though effective against individual soldiers, 20 mm ammunition is so large and heavy that its effects are nearly wasted on relatively small targets.

[edit] Types of ammunition

[edit] 20 mm weapons

Each weapon is listed with its cartridge type appended.

[edit] Current weapons

[edit] Historical weapons

Cartridge type indicates the diameter of projectile and the length of the cartridge that holds it, for example 20x102 is a 20 mm projectile in a 102 mm long case. Only rarely do two designers use the same case length, so this designation is usually definitive. Some cartridge types have additional letters or information about them listed.

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[edit] External links