20 mm cartridge

All 20 mm cartridges have an outside projectile (bullet) diameter and barrel bore diameter of approximately 0.787 in. These projectiles are typically 75 to(-) long, cartridge cases are typically 75 to(-) long, and most are shells, with an explosive payload and detonating fuze. Weapons using this caliber range from anti-materiel rifles and anti-tank rifles to aircraft autocannons and anti-aircraft guns.

• Illustration — A 20×102mm round (second from left) with.50 BMG rounds, golf ball, and a stick of 168-pin SDRAM computer memory Twenty millimeter caliber weapons are generally not used to target individual soldiers, but rather objects such as vehicles, buildings, or aircraft.

• High explosive (HE) • High explosive incendiary (HEI) • Armor-piercing (AP) • Semi-armor-piercing high explosive incendiary (SAPHEI) • Armour-piercing discarding sabot (APDS) • High explosive fragmentation tracer (HEF-T) • High explosive high capacity (HE-M) • Penetrator with enhanced lateral effect (PELE) • 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)

Each weapon is listed with its cartridge type appended.

• Weapon — Country of origin — Cartridge — Notes • Neopup PAW-20 — South Africa — 20×42mm • Denel NTW-20 — South Africa — 20×82mm Mauser • Denel Vektor GA-1 — South Africa • Vidhwansak — India • Anzio 20mm rifle — United States — 20×102mm • Arash anti-materiel rifle — Iran • M61 Vulcan — United States • M197 electric cannon — United States • M39 cannon — United States • GIAT M621 — France • ZVI PL-20 Plamen — Czech Republic • Nexter Narwhal 20A — France — Based on the M621 • Şahi 20-102 — Turkey • XM301 — United States • Denel NTW-20 — South Africa — 20×110mm Hispano • Metallic RT-20 — Croatia • Truvelo CMS 20x110mm — South Africa • Yugoimport-SDPR M71/08 — Serbia — Single barrel development of Zastava M55 • Oerlikon KAE (KAA/KAB) — Switzerland — 20×128mm — Formerly known as Oerlikon 204GK/5TG • Meroka CIWS — Spain • Escribano SENTINEL 20 — Spain — RWS • 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 • Nexter Narwhal 20B — France — Based on the 20 mm F2

• Weapon — Country of origin — Cartridge — Notes • Becker Type M2 20 mm cannon — German Empire — 20×70mmRB • Oerlikon FF — 20×72mmRB • Type 99 cannon, model 1 • Ikaria-Werke Berlin MG FF/M cannon — Nazi Germany — 20×80mmRB • Mauser MG 151/20 — Nazi Germany — 20×82mm • Ho-5 cannon — Japanese Empire — 20×94mm • Berezin B-20 — Soviet Union — 20×99mmR • ShVAK — Soviet Union • Helenius RK-20 APH — Finland — Derivative of the Helenius RK-97 12.7 mm anti-materiel rifle • Ghan-Krnka fortress rifle — Russian Empire — 20.3×95mmR — Bullet diameter 21 mm • Type 99 cannon, model 2 — Japanese Empire — 20×101mmRB • Solothurn S-18/100 — 20×105mmB • Automatkanon m/45 — 20×110mm — Aircraft autocannon • Automatkanon m/49 — Aircraft autocannon • Hispano-Suiza HS.404 and derivatives • Oerlikon F, FFL — 20×110mmRB • Polsten — 20×110mmRB • Colt Mk 12 cannon — 20×110mm USN — Advanced derivative of the HS.404 • Madsen 20 mm anti-aircraft cannon — 20×120mm • Type 97 automatic cannon — Japanese Empire — 20×124mm • Mauser MG 213 — Nazi Germany — 20×135mm • Solothurn S-18/1000 anti-tank rifle — Switzerland — 20×138mmB • Solothurn S-18/1100 anti-tank rifle — Switzerland • ST-5 20 mm AA gun — Switzerland • FlaK 30 and FlaK 38 single-barrel AA — Nazi Germany — Forerunner of Hispano-Suiza HS.820's post-war 20×139mm round • Flakvierling quadruple-barrel AA — Nazi Germany • MG C/30L aircraft gun — Nazi Germany • Rheinmetall KwK 30 and KwK 38 — Nazi Germany • Cannone-Mitragliera da 20/65 modello 35 (Breda) — Kingdom of Italy • Cannone-Mitragliera da 20/77 (Scotti) — Kingdom of Italy • Lahti L-39 anti-tank rifle — Finland — Solothurn Long • Lahti L-40 anti-aircraft gun — Finland • Nkm wz.38 FK anti-tank vehicle-mounted gun — Poland — Designated "heaviest machine gun", or "Najcięższy karabin maszynowy, Nkm", AA/AT (actually an autocannon) • Type 98 20 mm AA machine cannon and Type 4 20 mm twin AA machine cannon — 20×142mm • Automatkanon m/40 — 20×145mmR — Autocannon • Pansarvärnsgevär m/42 — 20×180mmR — Recoilless anti-tank rifle

(incomplete list) • Dimensions — Name — Date || data-sort-type="number" |Bullet diameter || Case length || data-sort-type="number"|Rim || data-sort-type="number"|Base || Shoulder || data-sort-type="number"| Neck || Cartridge length • 20.3×95R Ghan — 21 (.827) — 95 (3.74) — - — - — - — - — - • 20×150R — data-sort-value="21" |~21 (~.827) — 150 (5.9) — - — - — - — - — -

The usual nomenclature of ammunition 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. Though this designation is often assumed to be unique, this is not always the case, e.g. there are three different 20×110mm types which are not compatible. These may be distinguished in that some cartridge designations may include additional letters or names as a suffix, e.g. the various different types of 20×110mm might be distinguished as 20×110mm Hispano, 20×110mmRB and 20×110mm USN.

• B e.g. 20×138B: the cartridge has a belt which is used for headspacing, i.e. it helps ensure the correct positioning within the gun's chamber. • R e.g. 20×145R: a rimmed cartridge: the diameter of the rim forming the base is larger than that of the cartridge case itself. • RB e.g. Oerlikon 20×110RB: rebated rim, one where the rim is a smaller diameter than the case head allowing the extractor to follow it into the chamber, facilitating advanced-primer ignition, a recoil-moderating system.