20 × 102 mm

A naval version, the Mk 22, was also developed for use in fast patrol boats. The guns and their ammunition spread from the USA to NATO by way of various US aircraft supplied to NATO countries, and the cartridge was adopted by the French for the Mle 621 (F1) gun. PRIMEX Technologies introduced its 20 mm Improved Ammunition specifically for US high-performance aircraft cannon. Alliant Techsystems in conjunction with the US Navy developed the MK149-4 Phalanx round with a tungsten penetrator and sabot specifically for use with the Phalanx Close-In Weapon System (CIWS). Well over 3 million rounds have been produced. Description The rimless, bottlenecked case may be of brass or steel and is electrically primed using the M52A3B1 primer. Projectiles are of conventional pattern and weigh from 98 to 105 g, the IMR 7013, WC 870 or WC 872 propellant charge being regulated to give a muzzle velocity of 1,030 m/s. BRAZIL Manufacturer Companhia Brasileira de Cartuchos Type: HE-I M56A3: Steel shell with gilding metal driving band, loaded with 11 g of RDX; nose impact fuze M505A3; 100 g; V 7.5 1,000 m/s TP M55A2: Steel inert projectile; dummy fuze; 99 g; V 7.5 970 m/s TP-T M220: Body of HE-I shell, empty, red tracer; dummy fuze; 96 g; V 7.5 970 m/s CANADA Manufacturer SNC Industrial Technologies Inc Type: TP C98: Steel body, inert filled; aluminium nose, copper driving band; brass cartridge case; 99 g; MV 1,030 m/s. Interchangeable with US M55A2 FRANCE Manufacturer Giat Industries Type: HE-I M56A3: Steel body loaded with 11 g Hexal 65/35; impact fuze PD M505A3; 101.4 g; MV 1,040 m/s HE-I-T M242 : As for HE-I but with smaller HE loading and rear of shell bored for red tracer; fuzed MR221 PD with self-destruction between 3.5 and 9 seconds; 102 g; MV 1,040 m/s AP-I M53 : This projectile is unusual; the principal components are a solid AP steel pointed slug forming the main body, surmounted by a hollow alloy ogive filled with incendiary composition. The two are held together by a steel skin which reaches from the shoulder, where it grips the ogive to just above the driving band, where it grips the steel slug. The Tombak driving band is pressed into the steel slug, which continues to form the base of the projectile. Penetration is 10 mm of armour at normal engagement ranges. 101.2 g; MV 1,040 m/s AP-HC: Light-alloy body fitted with tungsten carbide penetrator; 95 g; MV 1,050 m/s AP-T (HC): As for AP-HC above but fitted with tracer TP M55A2: Steel shell body, empty; dummy fuze; 98.6 g; MV 1,045 m/s TP-T M220: As for TP but with red tracer; 100 g; MV 1,040 m/s GERMANY Manufacturer Buck Werke GmbH & Co Type: HE-I DM 23A1: As described above. Manufacturer Diehl GmbH Type: HE-I M-DN 71 : Steel-pointed shell with ballistic cap. Shell body contains a 5 g HE charge plus a zirconium incendiary pellet, plus a further incendiary filling in the ballistic cap. The base fuze M-DN 201 is fitted, giving a 200 µs delay, ensuring target penetration before detonation. 98 g; MV 1,030 m/s HE-I DM 23A1: Steel-pointed projectile with ballistic cap. The shell body is bored from the rear and filled with an incendiary composition and zirconium sponge pellet. Further incendiary material is in the ballistic cap. The shell will penetrate 25 mm of armour steel at 100 m range. 100 g; MV 1,033 m/s GREECE Manufacturer PYRKAL: Greek Powder & Cartridge Company Type: HE-I M56A3: Steel shell with gilding metal driving band, loaded with Hexal 70/30 and an impact fuze M505A3; 101 g; MV 1,030 m/s TP M55A2: Steel, inert projectile; dummy fuze; 101 g; MV 1,030 m/s ITALY Manufacturer Europa Metalli Type: TP M55A2: Steel shell with aluminium nose cap representing fuze; no filling. Electric primed. 98.6 g; V 24 1,030 m/s KOREA, SOUTH Manufacturer Daewoo Ammunition Corporation. Type: HE-I M56A3: Steel shell, loaded Hexal; nose impact fuze M505A3; 101 g; MV 1,030 m/s HE-I-T M246 : Steel two-section shell, HE in forward section, tracer in rear, with heat relay providing self-destruction; nose impact fuze; 100 g; MV 1,030 m/s TP M55A2: Steel inert projectile; dummy fuze; 101 g; MV 1,030 m/s TP-T M220: Body of HE-I shell, empty, red tracer; dummy fuze; 105 g; MV 1,030 m/s Manufacturer Poongsan Metal Corporation Type: HE-I M56A3: Steel shell, loaded Hexal; nose impact fuze M505A3; 101 g; MV 1,030 m/s HE-I-T M246 : Steel two-section shell, HE in forward section, tracer in rear, with heat relay providing self-destruction; nose impact fuze; 100 g; MV 1,030 m/s TP M55A2: Steel inert projectile; dummy fuze; 101 g; MV 1,030 m/s TP-T M220: Body of HE-I shell, empty; red tracer; dummy fuze; 105 g; MV 1,030 m/s NETHERLANDS Manufacturer NWM de Kruithoorn BV (now closed) Type: HE-I M56A3: Steel shell, loaded with Hexal; nose impact fuze M505A3; 101 g; MV 1,030 m/s HE-I-T-SD M246 : Steel two-section shell, HE in forward section, red tracer in rear, with heat relay providing self-destruction; nose impact fuze; 100 g; MV 1,030 m/s AP: Tungsten core in steel body with light-alloy ballistic cap; 104 g; MV 1,030 m/s AP-I: Steel core with first incendiary charge in the ballistic cap and second incendiary charge in shell base; 105 g; MV 1,030 m/s FAP: Frangible tungsten alloy core in steel body; no pyrochemical substances or HE; 102 g; MV 1040 m/s TP M55A2: Steel inert projectile; dummy fuze; 101 g; MV 1,030 m/s TP-T M220: Steel inert projectile, red tracer; dummy fuze; 100 g; MV 1,030 m/s NORWAY Manufacturer Nammo Raufoss Technology A/S Type: Multipurpose M70A2: Steel shell loaded with explosive and incendiary elements, the incendiary extending into the nose cap. Upon impact the ignition chain is started, resulting in delayed functioning inside the target. Equal ballistics to the M50 series ammunition. Projectile 100 g; MV 1,030 m/s Multipurpose M70 LD (low drag): This is similar to the M70 but has an improved projectile shape to reduce air drag during flight. Equal in ballistics to the US PGU-28/B round. Provides an increased hit probability and penetration compared to the M50 series ammunition. Long-burning Zirconium particles improve the fire start capability. 100 g; MV 1,050 m/s TP-R 3 (Target Practice with Reduced Richochet Risk): Matches M70 LD ballistically but the inert projectile breaks up on contact with the ground to reduce the risk of ricochets by a factor of at least 10 times Multipurpose NM140: The exterior of this round conforms to the standard US M2 Ball, but the bullet is a design patented by Raufoss which incorporates penetrative, incendiary and fragmentation effects. NM140 will defeat 16 mm of armour (Brinell 360) at 30º at 400 m; after penetration it will explode and produce about 20 effective fragments inside the target. There will also be a shower of incendiary particles which are still effective 15 m behind the target plate. No mechanical fuze is used because the need for detonators or sensitive high explosives has been eliminated. Muzzle velocity 900 m/s, bullet weight 43 g Multipurpose NM140A1: This is similar to the NM140 but with some minor changes to meet a US Navy specification Multipurpose tracer NM160: This is the NM140 but with the addition of a base tracer element. The inclusion of this reduces the effective fragmentation by about 30 per cent but does not affect the penetrative or incendiary performance. The tracer is a dark ignition type which is invisible to 50 m from the muzzle, fully visible from 200 to 1,500 m AP-S NM173: This has ballistic conformity to US Ball M2 but is characterised by tremendous penetration effect. Penetration of 20 mm armour plate at 0º NATO at 1,000 m and 11 mm armour plate at 30º NATO at 1,500 m PAKISTAN Manufacturer Pakistan Ordnance Factories Type: HE-I M56A3: Steel shell with gilding metal driving band, loaded H761 composition; nose impact fuze M505A3; 101 g; MV 1,030 m/s AP-I M53 : Steel pointed shell with alloy ballistic cap and incendiary filling; 101 g; MV 1,030 m/s TP M55A2: Steel inert projectile; dummy fuze; 101 g; MV 1,030 m/s SINGAPORE Manufacturer Chartered Industries of Singapore (CIS) Type: HE-I: Steel shell, loaded Hexal; impact fuze; 101 g; V 24 1,030 m/s HE-I-T: As for HE-I but with red tracer; 105 g; V 24 1,030 m/s AP-I: Pointed steel shot with ballistic cap loaded with incendiary mixture; 100 g; V 24 1,030 m/s TP: Body of HE-I shell, empty; dummy fuze; 100 g; V 24 1,030 m/s TP-T: Body of HE-I-T shell, empty, with red tracer; dummy fuze; 105 g; V 24 1,030 m/s SPAIN Manufacturer EXPAL SA Type: Multipurpose M70A1: The shell body carries a strikerless compression-ignition fuze over an incendiary filling over a high-explosive filling. On impact the nose crushes, causing the fuze to fire and ignite the incendiary composition which then ignites the HE filling, giving a forward blast to the burning incendiary fragments. The round will penetrate 20 mm of steel plate at 200 m range and 12 mm at 1,000 m range. The projected incendiary flame is 1 m long, giving excellent effect against protected fuel tanks. MV 1,030 m/s TP-T M220: Similar in shape to the M70A1 but with inert filling and base tracer SWITZERLAND Manufacturer Oerlikon Contraves Pyrotec AG Type: FAP PEA 280: Full calibre, frangible armour-piercing. Tungsten alloy penetrator with integral plastic-moulded ballistic cap and body with a steel rear portion, fitted with driving band. A ricochet free inert projectile with excellent performance against soft and light armoured targets. For air-to-air and air-to-ground, as well as ground-to-air and ground-to-ground applications. Ballistic match to US PGU-28/B; 102 g; MV 1,040 m/s TURKEY Manufacturer Makina ve Kimya Endüstrisi Kumuru ( MKEK ) Type: HE-I M56A3: Steel shell loaded RDX/incendiary composition; fuzed M505A3; 100 g; 1,030 m/s TP M55A2: Steel inert projectile; dummy fuze; 101 g; MV 1,030 m/s TP-T: Steel shell loaded inert with red tracer; dummy fuze; 103 g; MV 1,030 m/s UNITED STATES OF AMERICA Manufacturer General Dynamics, Ordnance and Tactical Systems Type: HE-I M56A3: Steel shell loaded RDX/incendiary composition; fuzed PD M505; 101 g; MV 1,027 m/s HEI-T M242 : Two-section shell, front loaded HE/incendiary mixture, rear loaded tracer; nose impact fuze; 102 g; MV 1,030 m/s AP-I M53 : Steel pointed shell with alloy ballistic cap and incendiary filling; 101 g; MV 1,027 m/s APDS MK149 Mod 4: Similar to AP-I M53 but with the addition of a red tracer; 102 g; MV 1,030 m/s tungsten carbide subprojectile in light alloy sabot; 110 g; MV 1,000 m/s. Specifically for US Navy Phalanx Close-In Weapon System (CIWS) but compatible with all M61 and M197 gun systems API-T MK 244 Mod 0: This is a companion round for the Optimised Gun Barrel (OGB) programme for the MK15 Phalanx CIWS. Compared with the MK149 the MK249 Mod 0 fires a tungsten alloy penetrator over 50 per cent heavier at essentially the same muzzle velocity TP M55A2: Steel inert projectile; dummy fuze; 101 g; MV 1,027 m/s TP-T M220: Body of HE-I shell, empty, with red tracer; dummy fuze; 105 g; MV 1,030 m/s MP-T-SD M940: Multipurpose; steel body loaded HE with a front covering incendiary mixture. This is covered by a support disk separating it from the nose incendiary mixture. The rear section of the body carries a red tracer with heat relay providing self-destruction; 105 g SAPHEI PGU-28/B: Steel shell with alloy nose cap. Shell contains a sponge zirconium incendiary in its base, with a main HE (Composition A4) filling above, followed by a body incendiary filling and a nose incendiary filling. 100 g; MV 1,052 m/s SAPHEI PGU-28A/B: An upgraded PGU-28A with an improved projectile nose/body joint configuration and optimised propulsion/driving band system. The driving band and matching propulsion charge reduces barrel wear and chamber fatigue loads with no alteration in muzzle velocity. 100 g; MV 1,052 m/s TP PGU-27/B: Inert steel projectile representing PGU-28/B; 100 g; MV 1052 m/s TP-T PGU-30/B: Inert steel projectile representing PGU-28/B but with tracer; 100 g; MV 1052 m/s Manufacturer Alliant Techsystems, Kilgore Operations Type: M56HEI: Steel shell loaded with RDX or RDX/TNT. PD M505A3 fuze. Also available as training round. Projectile weight, 260 g; MV 1,030 m/s M221 HEI-T: Virtually identical to HE-I M56 but with tracer element. Projectile weight 260 g; MV 1,030 m/s M242 HEI-T-SD: As HEIT M221 but with self-destruct function. MV 1,030 m/s. Also available as a training round. MK149-4 Phalanx: For Phalanx CIWS. Tungsten penetrator held in sabot. WC 859 propellant giving MV of 1,128 m/s. Round weight 253 g. Issued in 200 or 250 round bulk packs. No tracer element TP M55 : Inert steel projectile with dummy fuze. Projectile weight 260 g; MV 1,030 m/s TP-T M220: As TP M55 but with tracer. MV 1,030 m/s HPT M54A1: High-Pressure Test round for proof-testing 20 mm gun barrels. Round weight 320 g PGU-27/B TP: An inert projectile for use as a cost effective training substitute for the PGU-28/B SAPHEI round. Projectile weight 266g; MV 1,039 m/s. PGU-28/B SAPHEI: Round for use in M61 aircraft cannon against light armoured vehicles. Projectile weight, 264 g; MV 1,039 m/s