20 mm caliber

20 mm refers to a common firearms bore diameter, typically used for cannon or autocannons. 20 mm cartridges have an outside bullet diameter and inside barrel diameter of 0.787 inches (20.0 mm). Projectiles are typically 75 to 127 mm (3–5 in) long. Cartridge cases are typically 75 to 152 mm (3–6 in) long and most are shells, with an explosive filling and detonating fuze.

Weapons using this calibre range from anti-materiel rifles and anti-tank rifles to aircraft autocannons and anti-aircraft guns.


20×102mm round with .50 BMG rounds, golf ball, and a stick of SDRAM computer memory.

20 mm caliber weapons are generally not used to target individual soldiers, but against targets such as vehicles, buildings, or aircraft.

Types of ammunitionEdit

20 mm weaponsEdit

Each weapon is listed with its cartridge type appended.

Current weaponsEdit

Weapon Country of origin Cartridge Notes
Neopup PAW-20   South Africa 20×42mm
Denel NTW-20   South Africa 20×82mm Mauser
Vidhwansak   India
Anzio 20mm rifle   United States 20×102mm
M61 Vulcan   United States
M197 electric cannon   United States
M39 cannon   United States
GIAT M621   France
ZVI PL-20 Plamen   Czech Republic
Metallic RT-20   Croatia 20×110mm Hispano
Oerlikon KAA/KAB    Switzerland 20×128mm Formerly known as Oerlikon 204GK/5TG
Meroka CIWS   Spain
Oerlikon KAD    Switzerland 20×139mm Formerly known as Hispano-Suiza HS.820
GIAT M693/20 mm modèle F2   France
Rheinmetall Rh 202   Germany
Denel Land Systems GI-2   South Africa

Historical weaponsEdit

Weapon Country of origin Cartridge Notes
Ghan-Krnka fortress rifle   Russian Empire 20.3×95mm R Bullet diameter 21 mm
Type 99 cannon, model 2   Japanese Empire 20×101mm RB
Solothurn S-18/100    Switzerland 20×105mm B
Bofors m/45   Sweden 20×110mm
Bofors m/49   Sweden
Hispano-Suiza HS.404 and derivatives    Switzerland
Oerlikon F, FFL    Switzerland 20×110mm RB
Polsten   Poland 20×110mm RB
Colt Mk 12 cannon   United States 20×110mm USN Advanced derivative of the HS.404
Madsen 20 mm anti-aircraft cannon   Denmark 20×120mm
Type 97 automatic cannon   Japanese Empire 20×124mm
Mauser MG 213   Nazi Germany 20×135mm
Breda Model 35   Kingdom of Italy 20×138mm B
Nkm wz.38 FK   Poland Designated "Heaviest Machine Gun", or "Najciezszy karabin maszynowy, Nkm," AA/AT (actually an autocannon)
Rheinmetall 2 cm KwK 30   Nazi Germany
Scotti 20 mm   Kingdom of Italy
Solothurn S-18/1000 Long    Switzerland
FlaK 38   Nazi Germany Forerunner of Hispano-Suiza HS.820's post-war 20×139mm round
Lahti L-39   Finland Solothurn Long
Bofors m/40   Sweden 20×145mm R
Becker Type M2 20 mm cannon   German Empire 20×70mm RB
Oerlikon FF    Switzerland 20×72mm RB
Type 99 cannon, model 1   Japan
Ikaria-Werke Berlin MG FF/M cannon   Nazi Germany 20×80mm RB
Mauser MG 151/20   Nazi Germany 20×82mm
Ho-5 cannon   Japanese Empire 20×94mm
Berezin B-20   Soviet Union 20×99mm
ShVAK   Soviet Union 20×99mm R

Cartridge type indicates the diameter of projectile and the length of the cartridge that holds it; for example 20×102mm 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.

See alsoEdit


External linksEdit