20 mm caliber

"20mm" redirects here. For the model scale, see List of scale model sizes.

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 few weapons (aside from shotguns and large game hunting rifles) which have been built that fire projectiles between .50 caliber (0.50 inch/12.7 mm, roughly 13 mm caliber) and 20 mm caliber, though the 14.5 mm caliber is used by some Soviet machineguns such as the KPV and antitank rifles such as PTRS, PTRD, and NTW-20.

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

20 mm caliber cartridges have an outside shell diameter and inside barrel diameter of 0.79 inch (20 millimeters). Projectiles or shells are typically 75-127 mm (3-5 inches) long. Cartridges are typically 75-152 mm (3-6 inches) long. 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 (3395 ft/s). For a simple slug round this is a muzzle energy of 53,567 joules (or approximately 39,507 ft-lbf).

Usage

20 x 102 mm round 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.

Types of ammunition

• High Explosive (HE)
• High Explosive Incendiary (HEI)
• Armour Piercing (AP)
• Armour Piercing Incendiary (API)
• Discarding Sabot Armour Piercing or proper APDS
• Target Practice- Inert projectile (i.e., PGU-27A/B). Used for training. (TP)
• Target Practice Tracer- Inert projectile with tracer material in base for visual trajectory tracking (i.e., PGU-30A/B). (TP-T)

20 mm weapons

Each weapon is listed with its cartridge type appended.

Current weapons

• Denel NTW-20: 20×82mm Mauser or 20×110mm Hispano caliber
• GIAT M621: 20×102mm
• M61 Vulcan: 20×102mm (PGU-28/B)
• M197 Gatling gun: 20×102mm
• Pontiac M39: 20×102mm
• RT-20 bolt-action rifle: 20×110mm
• Anzio 20mm. Vulcan Anti Material Rifle
• Oerlikon KAA & KAB: 20×128mm (formerly the Oerlikon 204GK and 5TG respectively)
• Meroka: 20x128mm
• Oerlikon KAD: 20×139mm (formerly the Hispano-Suiza HS.820)
• GIAT M693: 20×139mm
• Rheinmetall MK 20 Rh 202: 20×139mm
• Vidhwansak: 20×82mm
• Anzio Sniper Rifle 20mm: 20x102mm

Historical weapons

• Colt Mk 12 cannon: 20×110mm (Mk 12 is an advanced derivative of the HS.404)
• Hispano-Suiza HS.404 and derivatives: 20×110mm
• Hispano-Suiza HS.804: 20×110mm
• Lahti L-39: 20×138mm B (Solothurn Long)
• Rheinmetall FlaK 38: 20×138mm B forerunner of Hispano-Suiza HS.820 post-war 20×139mm round
• Madsen 20 mm anti-aircraft cannon: 20x120mm
• Mauser MG 213: 20×135mm
• Oerlikon FF: 20×72mm RB
• MG FF/M cannon: 20×80mm RB
• Mauser MG 151/20: 20×82mm
• Nkm wz.38 FK designated: "Heaviest Machinegun" "Hmg" or "Najciezszy karabin maszynowy, Nkm," AA/AT 20x138 mmB autocannon
• Oerlikon F, FFL: 20×100mm RB
• ShVAK: 20×99mm R
• Solothurn S-18/100: 20×105mm B
• Solothurn S-18/1000: 20×138mm B
• Type 99 cannon : 20x72RB

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.

See also

• Category:20mm sniper rifles
• .50 BMG
• 14.5 × 114 mm
• 20x110mm USN
• 23 mm caliber
  • 23 × 115 mm
  • 23 × 152 mm
• 25 mm caliber
• 30 mm caliber
• autocannon
• caliber
• cannon

External links

• FAS: 20 mm Cannon Ammunition
• ATK produced 20, 25 & 30 mm caliber ammunition
• Rapid Fire: 20 mm Cartridge Data Table
• Rapid Fire: 20 mm Antitank Rifle Cartridges image
• Rapid Fire: 20 mm Autocannon Cartridges WWII image 1
• Rapid Fire: 20 mm Autocannon Cartridges WWII image 2
• Rapid Fire: 20 mm Autocannon Cartridges Post-WWII image