Autocannons For GURPS

"Get one today, because the guy you meet tomorrow may already have one!"
-- Uncle Albert's™ Auto Stop & Gunnery Shop, 2035 Catalog

GURPS High-Tech thoroughly covers most types of small arms and also includes a fair number of support weapons. One class of weapons is absent, however: the automatic cannon. Most of these are vehicular armaments and are thus included to a certain extent in GURPS Vehicles. But the scope of the latter is very different from that of HT: It is designed to provide generic game stats only, in contrast to HT, which strives to represent specific weapons and also tries to enlighten the reader on the weapons' service histories and interesting details. Some autocannons would fit nicely into HT, and indeed some are mentioned in various chapters, but eventually the whole class was left out because of space constraints.

This article has 25 autocannon entries HT-style, that is with a lot of real-world information. Game statistics are of course also here, based on what VE has to say about the topic. However, the weapons were not reverse-engineered using the rules, instead most of the data was taken directly from reference works wherever possible. Nevertheless, all are fully compatible with VE.

* * *

Autocannons are defined here as fully automatic weapons with a caliber of 20mm or larger.

Rotary autocannons are multi-barrel weapons often powered by an electric, hydraulic or pneumatic motor, resulting in increased rate of fire (the Russian 23x115mm Izhmash GSh-6-23M has RoF 150!) and high reliability (several 10,000 shots between failure). They are often called Gatling cannons after the hand-cranked multi-barrel gun invented by Dr. Richard Gatling. Many self-powered rotary cannons also exist (almost all Russian designs are gas-operated). Most rotary weapons are based on the first such weapon that reached service, the U.S. M61 Vulcan. One drawback of rotary cannons is their spin-up time, that is, they require a split second to reach their selected rate of fire. Thus, 1-second bursts or the first second of a longer burst consist only of about 70% of the noted RoF.

Externally powered autocannons are single-barreled guns powered by an external motor. The most prominent examples are members of the Chain Gun-family, where the action is driven by an internal chain-mechanism. However, there are also other motor-driven weapons. All externally powered guns have a high reliability.

Revolver cannons, originally invented in Germany during WWII, are single-barreled guns with several chambers not unlike a hand-held revolver. This arrangement provides higher rates of fire while allowing for a compact, lightweight and reliable weapon. Revolver cannons can also be found with motor-driven actions.

All belt-fed autocannons up to mid TL7 were single-feed only, which meant they were often loaded with a mix of ammo types on a single belt. For example, German fighters with the MG151/20 fired a 1:1:1 mix of SAPHEC-SD, SAPHE-SD and APEX-SD. This was usually neither economical nor very effective. In the mid-1960s, the double-feeder was invented, and common on ground service guns by the 1970s. A cannon equipped with it can feed ammunition from either side, so that the gunner can choose between two different types, as need arises. Some of the most recent guns even have triple-feeders. This is generally not available for rotary and revolver guns (although possible and already proposed for certain anti-aircraft applications), which therefore today mostly fire multi-purpose rounds such as SAPHE, HEDP or FAPDS.

Note that autocannon projectiles are almost universally fitted with a tracer (e.g. HE-T, APFSDSDU-T). See Walking the Burst,, p. HT78. In keeping with VE, this is not noted in the weapon chart. Most autocannon projectiles are highly volatile and will count as flame attack (p. VE183), including SAPLE, SAPHE, SAPHEC, HE, HEDP, AHEAD, FAPDS, API, APEX, APDU, APDSDU and APFSDSDU. Weapons mounted in aircraft (including helicopters) can not use saboted rounds. The sabots pose a distinct danger for jet engines and propellers. The same guns used in ground or naval applications are of course not restricted by this.

Most modern autocannons, especially for use in or against aircraft, have dual firing rates, a lower one against ground targets and a higher one against airborne targets. Note that many autocannons are incapable of single shots. Most TL7 weapons have burst limiters included in their fire control systems, which help conserve ammunition.

Maxim QF 1-pdr Mk I, 37x94mmR Hotchkiss, UK, 1889

By definition, this was the first autocannon ever. The British water-cooled Maxim machine gun (pp. HT117-118) was scaled up to fire the same 1-pound blackpowder shell as the Hotchkiss Mle 1877 mechanical rotary gun (p. HT117). It was originally intended for use against torpedo boats. The Maxim was first adopted by a number of naval forces, including the British (1889) and Imperial German (1897), and also the French and about 30 others. Germany made it under license. It was nicknamed the Pom-Pom during the Anglo-Boer War in South Africa, where both sides used it. German Navy guns also saw land service during the Chinese Boxer revolt, and many were still in service in WWI, when the British Army and Navy, among others, used it as an anti-balloon gun on horse-drawn field carriages and armored cars. It was adopted by the Imperial German Army in 1915, which found it useful against early tanks. The Pom-Pom had a short barrel and fed from a non-disintegrating 25-round belt. The Germans also used 50-round and 100-round belts. It was manually aimed and fired. During WWI, APEX and SAPHE rounds were introduced by some nations.

Becker Kanone, 20x70mmRB Becker, Germany, 1917

The first light autocannon, this gun was patented in 1914. It was a simple blowback weapon, used as the flexible Becker FlzK on heavy aircraft. Mounted on a tripod (60 lbs.) it was called the Becker TAK and employed against tanks and aircraft. It was manually controlled, had a medium barrel and fed from a top-mounted 12-round box magazine. The gun was only used by the Germans during WWI.

The Becker FlzK was mounted on some AEG G IV bombers and Albatros J I close-support aircraft.

Oerlikon S, 20x110mmRB Oerlikon, Switzerland, 1927

The Oerlikon S cannon was a gradual development of the Becker gun, the patents having been sold to the Swiss company. During the late 1930s an improved variant, the SS (1938), was widely adopted as an anti-aircraft gun, mounted on tripods, trailers and especially ships; RoF 8. All models usually fed from a 60-round drum, which weighed 62 lbs. loaded. Among the Oerlikon users were Japan and the USSR, but the main operators of the SS were Britain and the USA. Hundreds of thousands were made.

The far less successful Oerlikon FFS (1935) was an aircraft weapon; use the same stats except for Ewt 86, RoF 7. Hispano-Suiza located near Paris produced a licensed copy of the FFS called the HS.7; Ewt 103, RoF 6.

The French Dewoitine D.501 fighter (1935) had a single HS.7 gun with a 60-round drum, firing through the propeller hub.

In 1936 Hispano-Suiza came out with their own development, the HS.404, which became the main competitor of the Oerlikon. Although a completely different design, it was very similar operationally and both widely exported and license-made. It used the 20x110mm Hispano-Suiza cartridge, which was not interchangeable with the Oerlikon round. During WWII it was mainly employed as an aircraft gun. The original HS.404 usually fed from a 60-round drum, but by 1941 improved British and U.S. aircraft versions used disintegrating belts. The company introduced their own belt-feed model, the HS.804, shortly after WWII. Use the Oerlikon S stats, except for Ewt 105-121, RoF 8 (drum-feed HS.404); Ewt 114, RoF 13 (belt-feed HS.804); Ewt 95, RoF 10 (drum-feed British Mk II); Ewt 92, RoF 12 (belt-feed British Mk V); Ewt 112, RoF 10 (belt-feed U.S. M2); Ewt 95, RoF 13 (belt-feed U.S. M3) and Ewt 90, RoF 13 (belt-feed U.S. M24).

The Royal Air Force Supermarine Spitfire Mk IB fighter (1939) had two Mk II guns in the wings with 60 rounds per gun, the Hawker Hurricane Mk IIC fighter (1940) had four Mk II guns in the wings with 60 rounds per gun (p. HT89), the U.S. Army Air Corps Lockheed P-38F Lightning fighter (1942) had one M2 cannon with 150 belted rounds, the U.S. Navy Grumman F8F-1B Bearcat fighter (1945) had four M3 guns in the wings with 200 belted rounds each (p. HT91), the U.S. Navy North American F-1C Sabre fighter (1953) had four M24 guns in the nose with 132 belted rounds per gun and the Argentine FMA IA-58B Pucará ground attack fighter (1975) mounted two HS.804 guns with 270 belted rounds per gun (p. SO15).

During the 1960s, the U.S. Navy converted thousands of M3 guns to the MK16 MOD 0 deck gun; use the same stats, except for Ewt 95, RoF 10.

The LCM(R) Monitor riverine boats (1963) mounted one MK16 MOD 0 with 365 rounds in the aft turret.

The German Ikaria MG-FF (1936) was a modified variant of another Oerlikon model, the FFF, which very much resembled the original Becker gun. It was a compact weapon with medium barrel and fired the 20x80mmRB round; Dam 5dx2(0.5) plus 1d-4[2d], 1/2D 1,000, Max 4,800, Ewt 62, RoF 9, WPS 0.44. It usually fed from a 30-round or 60-round drum. API and APEX rounds were available, but the modified MG-FF/M (1940) mainly fired SAPHEC rounds.

The Messerschmidt Bf 109E-4 fighter (1940) mounted one MG-FF/M in each wing with 60 rounds per gun. The Heinkel He 111H-16 transport (1941) mounted one flexible MG-FF/M in the nose with 30 ready rounds and 5 spare drums.

Bofors m/36, 40x311mmR Bofors, Sweden, 1936

This Swedish anti-aircraft gun was designed beginning in 1928 and became a huge success during the 1930s and 1940s. More than 20 nations adopted it in that era in widely varying numbers, among them Argentina, Finland and Turkey, and many more after WWII. The basic gun was license-made in Austria, Belgium, Canada, Czechoslovakia, Great Britain, Hungary, Norway, Poland and the USA. After WWII, it was also made in Germany and Italy. It was used both on ground and naval mounts, including trains and submarines, and often found in twin or quadruple installations. The Bofors fed from 4-round clips, although bulky feeders holding 10, or after WWII up to 101, rounds were developed and used by some nations (but usually confined to naval applications).

The Swedish Army Lvakan m/36 and its copies were the most widespread ground mounts. They had a single gun on a four-wheeled trailer. Some 24 rounds would be stowed on the trailer right beside the gun, with about 200 more on the towing truck. Such an anti-aircraft mount would mass around 2.5 tons. The Cadillac M42 Duster self-propelled armored anti-aircraft system (1951) of the U.S. Army carried two license-made Watervliet M2A1 guns in an open turret with 480 stowed rounds.

The U.S. Navy mounted a single MK3 on the LCT landing ships (1940), while the Vietnam-era LCM(R) Monitor riverine craft (1963) mounted a MK52 in the bow turret, fed by a 48-round drum.

The U.S. Air Force's Rockwell AC-130U Pave Spectre III gunship (1994) carried a side-firing M2A1 gun with shortened barrel and 276 stowed rounds (p. SO89).

After WWII, the gun was commonly known as the L60 (although its barrel length actually was 56 calibers), to distinguish it from the improved L70 or m/48, which fired the more powerful 40x365mmR cartridge; Dam 6dx7(0.5) plus 4d[4d], 1/2D 5,000, Max 13,700, Ewt 770, RoF 5*, WPS 5.5.

Mauser MG151/20, 20x82mm Mauser, Germany, 1940

An improved version of the 15x96mm Mauser MG151 heavy machine gun, which was modified to accept a more effective cartridge by simply replacing the barrel. It was one of the first guns to fire electrically primed ammunition and was a standard light cannon of many German, Italian and some Japanese and Romanian aircraft, mainly in fixed mounts. Later in the war it was also used on single and triple anti-aircraft mounts and even improvised ground tripods and naval fast attack boats. After WWII it was used for some time by Czechoslovakia, France, Israel and South Africa, France even producing it until 1970. The MG151/20 used a disintegrating belt.

The Junkers Ju 87D-5 STUKA ground attack aircraft (1940) had one gun with 180 rounds in each wing. The Messerschmidt Bf 109G-5 fighter (1942) had a single gun with 200 rounds firing through the propeller hub. The Focke-Wulf Fw 190A-8 fighter (1940) had four wing-mounted guns, two synchronized in the wingroots with 250 rounds each and two unsynchronized with 140 rounds. The Japanese Kawasaki Ki-61-Ia Hien (Tony) fighter (1942) mounted one in each wing, with 120 rounds per gun. Some French Aérospatiale SA 316B Alouette III helicopters (1960) mounted a MG151/20 with 480 rounds (p. SO86).

The South African Vektor GA-1 Rattler (1989) was a slightly modernized copy; use the same stats except for Ewt 86. By installing a few replacement parts, it could be converted in 10 minutes to fire the 12.7x99mm Browning (Dam 12d, 1/2D 1,500, Max 6,800, RoF 10, WPS 0.25). It was available on armored vehicle, aircraft and naval mountings.

The Atlas Oryx helicopter (1991), a derivative of the Aérospatiale SA330L Puma (p. SO86), could mount one GA-1 as door gun with 240 ready rounds.

Tulamash VYa-23, 23x152mmB Volkov-Yartsyev, USSR, 1940

The most powerful small caliber autocannon of WWII was an aircraft weapon for ground attack. It was scaled up from the 12.7x108mm Beresin UBK heavy machine gun and had a long barrel.

The Lavochkin-Gorbunov-Gudkov LaGG-3 Tip 8 fighter (1941) had a single gun firing through the propeller hub, with 80 rounds. The Ilyushin Il-2M Tip 3 Shturmovik ground attack aircraft (1942) had a VYa-23 with 250-round belt in each wing.

The Tulamash AZP-23 (2A7) was a later development installed on the ZSU-23-4. It used the same cartridge case as the VYa-23, but ammunition was not interchangeable; use the same stats except for Ewt 176, RoF 15.

The ZSU-23-4 Shilka armored anti-aircraft vehicle (1966) mounted four AZP-23 guns with 500 ready rounds each.

Rheinmetall-Borsig BK3.7, 37x265mmR Rheinmetall, Germany, 1942

This aircraft gun was based on the FlaK18 anti-aircraft gun of the 1930s. It was used both as an heavy aircraft destroyer and tankbuster. It fed from 6-round clips inserted from the side. The APCR round introduced in 1944 was in short supply because of severe lack of tungsten.

The Junkers Ju 87G-1 Kanonenvogel ground attack aircraft (1943) carried two guns with 12 rounds per gun below the wings, while the Henschel Hs 129B-2/Wa heavy fighter (1943) carried one as a belly gun with 6 rounds ready to use, plus 66 in reserve.

Rheinmetall-Borsig MK108, 30x90mmRB Rheinmetall, Germany, 1943

A cheap, lightweight gun designed for air-to-air combat, the shells carrying enough explosive to bring down even heavy Allied bombers, although its short range was a distinctive drawback (pilots usually opening fire at 300 yards). The action was scaled up from the old Becker. The MK108 was extremely compact and had a short barrel. It used electrically primed ammunition in disintegrating belts.

The Messerschmidt Bf 109K-4 fighter (1944) had one gun firing through the propeller hub with 60 rounds, while the Messerschmidt Me 262A-1 Schwalbe jet fighter (1944) had four nose guns, two with 100 rounds each and two with 80 rounds each.

Mauser MK213, 30x85mmB Mauser, Germany, 1945

This revolutionary gun was the first revolver cannon, with five chambers and a medium barrel. Its high rate of fire, good reliability and effective Minengeschoss completely outclassed all Allied weapons of the time. In our reality, only 15 prototypes were made before the war ended, but had it continued as postulated in Alternate Earths, the MK213 would have become the new standard gun of the Luftwaffe.

The Messerschmidt Me 262F-1 jet fighter (1946) had two guns with 120 rounds per gun, while the Horten Ho 15A-1 flying wing jet fighter (1946) had two guns with 150 rounds each.

DEFA Mle 552, 30x113mmB DEFA, France, 1954

A direct copy of the experimental 30x85mmB Mauser MK213, this weapon was an instant success. It was a gas-operated revolver cannon with five chambers and medium barrel. The Mle 552 was adopted by the French Air Force as the CN-MIT-30-F1 and made in several variants, including the Mle 554 with RoF 18/30. All models were widely exported, and some were licensed to Israel and South Africa.

The Dassault Mirage IIIC fighter (1960) mounted two Mle 552 guns with 125 rounds per gun. The Brazilian AMX A-1 ground attack aircraft (1990) had two Mle 554 guns with 125 rounds per gun.

The British Royal Ordnance ADEN-series was very similar and fired ammunition identical except for the priming; use same stats except for Ewt 192.

The SEPECAT Jaguar GR.1 ground attack fighter (1973) had two ADEN Mk 4 with 150 rounds per gun. The BAe Sea Harrier FRS.1 V/STOL fighter (1979) carried two ADEN Mk 4 with 130 rounds per gun in a belly pack.

Tulamash GSh-23, 23x115mm Afanasiev-Makarov, USSR, 1959

A standard Soviet aircraft cannon, the GSh-23 was a twin-barreled gun whose medium-length barrels fired alternatively, an arrangement first used in the German 7.92x57mm Vorwerk-Gast MG17 of WWI. It fed from a disintegrating belt. The GSh-23 was license-made in China and Yugoslavia. Shrapnel rounds were available for ground attack. They exploded at 1/2D, scattering pellets in a narrow cone along the flight path. Even chaff and IR-decoy rounds were made in this caliber, but only used in bombers.

The gun was widely used and most often found in a belly pack with 200 rounds, for example on the MiG-21PFM (Fishbed-F) fighter (1964) or MiG-23M (Flogger-B) fighter (1973), but it was also installed in the chin turret of the Mi-24VP (Hind-E) attack helicopter (1992), feeding from a 470-round belt (pp. SO88). The Tupolev Tu-22M-2 (Backfire-B) strategic bomber (1971) had two in a remote-controlled tail barbette, each with 600 rounds.

Ford Aeronutronic M129, 40x53mmSR NATO, USA, 1963

Although strictly speaking an automatic grenade launcher, it was used operationally very similarly to a cannon. The M129 was externally powered by an electric motor and had a short barrel. It fired the same belted ammunition as the Naval Ordnance MK19 MOD 0 grenade machine gun (p. HT121). The gun was widely used during the Vietnam War.

The M129 was first installed in the chin turret of the Bell AH-1G Cobra attack helicopter (1967) with 300 grenades (side-by-side with a 7.62x51mm GE M134 minigun and its 4,000 rounds). The experimental Lockheed AH-56A Cheyenne attack helicopter (canceled 1972) mounted it in a chin turret with 780 rounds. The USAF used it as a doorgun on the Bell UH-1N helicopter (p. SO81).

General Electric M61A1 Vulcan, 20x102mm M50, USA, 1964

After WWII, the U.S. Air Force started to look for a new aircraft gun based on the multi-barrel Gatling guns. In 1956, the M61 Vulcan was adopted. It was an externally powered cannon with six long barrels, feeding from a disintegrating belt. First installed in the Lockheed F-104A Starfighter, it was soon superseded by the M61A1 variant, which used a linkless feeder for better reliability and higher rate of fire. It remained the standard American aircraft gun for many decades. Like most modern aircraft cannons, the M61A1 had two selectable rates of fire, low (RoF 66) or high (RoF 100). The original M61 could only fire at RoF 66. The ammo was contained in a large drum magazine, whose capacity differed depending on the installation. The M61A1 was license-made in Italy and Japan.

The more recent M61A2 (1990) had been reduced in weight; Ewt 200.

The Lockheed F-104A Starfighter (1956) mounted the M61 with 750 rounds, the McDonnell Douglas F-15C Eagle (1979) had the M61A1 with 940 rounds, the General Dynamics F-16A Fighting Falcon (1979) had the M61A1 with 511 rounds, and the Lockheed Martin F-22A Raptor (2002) carried the M61A2 with 480 rounds. The Boeing B-52H Stratofortress bomber (1961) used to have one M61 as remote-controlled tail gun with 1,242 rounds (RoF 41). The Lockheed AC-130H Pave Spectre II gunship (1972) carried two M61A1 guns with 3,000 rounds per gun, both firing to the left at RoF 41 ( p. SO89).

The GAU-4/A (1966) was a self-powered version (Ewt 275, Pow 0) installed in a gunpod with 1,200 rounds.

A single pod was carried by Royal Air Force McDonnell Douglas Phantom FGR.2 fighter/bombers (from 1969).

The M168 was the U.S. Army's variant for use in anti-aircraft systems, mounted on a trailer or armored vehicle; Ewt 299, RoF 16/50. It was license-made in South Korea.

The M163 Vulcan air defense system (1968) mounted an M168 gun in a one-man turret on a modified FMC M113A1 armored personnel carrier. It had 1,100 rounds ready-to-fire and 1,000 in reserve.

It was also part of the shipborne MK15 Phalanx radar-controlled Close-In Weapon System (CIWS) first deployed in 1980. It typically fired APDSDU rounds in 60-round or 100-round bursts; Dam 6dx5(3), 1/2D 2,600, RoF 50, WPS 0.6.

The USS Enterprise aircraft carrier mounted three Phalanx stations from 1980, each with an integral magazine with 989 rounds, while the FFG-7 Perry-class frigates (from 1980) mounted one each.

OTO Melara 76/62 Compatto, 76x636mmR OTO Melara, Italy, 1967

One of the most popular medium-caliber naval weapons, adopted by 50 navies and license-made in Australia, India, Japan, Spain and the USA (as the MK75 MOD 0). It had a long, seawater-cooled barrel and was useful against both ships and aircraft. Anti-armor ammunition had been developed for use in armored vehicles, but was not usually used with this gun. It was typically installed in a remote-controlled gun turret.

The 76/62 Super Rapido was an improved version with RoF 2*.

The Italian Audace destroyer (1973) carried four Super Rapido with 85 ready rounds per gun. The U.S. Navy FFG-7 Perry-class frigates (1978), the PHM-1 Pegasus-class hydrofoil patrol ships (1978) and the U.S. Coast Guard WMEC-901 Bear-class cutters (1983) all mounted one MK75 MOD 0 with 80 ready rounds.

General Electric GAU-8/A Avenger, 30x173mm Oerlikon, USA, 1975

The most powerful cannon ever carried by an aircraft. It was a hydraulic rotary cannon with seven long barrels and a linkless feed. Its recoil was so high that firing it considerably slowed down the jet-engined aircraft it was installed in! The main round was APDU, which was usually mixed 5:1 with SAPHE. Its ammo had alloy cases.

The GAU-8/A was designed specifically for the Fairchild A-10A Thunderbolt II ground attack aircraft (1977). When introduced, it offered dual firing rates (RoF 35/70), but since the late 1980s, the gun on the A-10A could only fire at RoF 65. The A-10A had a 1,174-round drum magazine.

The Dutch SGE-30 Goalkeeper (1980) was a shipborne CIWS armed with the GAU-8/A. It fired an APDS or FAPDS round at RoF 70. From 1988, the British Invincible-class aircraft carriers mounted two Goalkeeper systems with 1,190 ready rounds each.

A development from this gun was the GAU-13/A, a 4-barreled weapon powered by a pneumatic motor. Use the same stats except for Ewt 339, RoF 40, Pow 44.75 kW. It was used in a gunpod with 353 rounds.

Tulamash 2A42, 30x165mm Shipunov, USSR, 1976

Another widespread Soviet design, this weapon was originally developed for the BMP-2 infantry fighting vehicle. It was a conventional single-barreled gun with dual-belt feeder. The 2A42 was license-made in Bulgaria, Czechoslovakia and India.

The BMP-2 (1976) carried 305 SAPHE rounds and 195 AP rounds ready-to-use.

The Kamov Ka-50 (Hokum-A) attack helicopter (1995) was also armed with this cannon. It carried 250 SAPHE and 250 APEX rounds (RoF 5/15).

The improved 2A72 (1990) was a lighter and less complex weapon. Use the same stats except for Ewt 185, RoF 5*.

The 2A72 armed the BMP-3 (1990), which carried 305 SAPHE rounds and 195 APDS rounds.

Mauser BK27, 27x145mmB Mauser, West Germany, 1977

This belt-fed revolver cannon with five chambers and a long barrel was based on the experimental 20x135mm Mauser MG213 of 1945. It had a high rate of fire and very good reliability. It typically fired 10- or 20-round bursts.

The multi-national Panavia PA200 IDS Tornado fighter/bomber (1982) had two BK27 with 180 rounds per gun (typically SAPHE), while the Swedish SAAB JAS39A Gripen (1995) carried a single gun with 120 rounds.

In 2001, the BK27 installed on the remote-controlled MLG27 mount entered service with the German Navy. The MLG27 accommodated a 90-round belt and fired FAPDS.

The Mauser BK27-2 was an improved version with linkless feed; Ewt 297.

It armed the multi-national Eurofighter EF2000 Typhoon (2001), which carried 150 rounds. The same gun licensed to Boeing was selected for the Joint Strike Fighter developed for the U.S. and British militaries (either the Boeing F-32A or Lockheed Martin F-35A, from about 2008). The F-32A/B carried 150 rounds of HEDP.

Izhmash GSh-301, 30x165mm Shipunov, USSR, 1978

A belt-fed gun with a water-cooled medium barrel, very light and powerful. It was developed in the late 1970s and entered service in 1984. The GSh-301 fired electrically primed ammunition, which was otherwise similar to the rounds used by the 2A42.

The MiG-29 Strizh (Fulcrum-C) fighter/bomber (1984) carried one gun with 150 rounds, as did the Su-27 (Flanker-B) fighter (1984).

Hughes M242 Bushmaster, 25x137mm Oerlikon, USA, 1981

Design of this weapon started in 1976, and it was first fielded in 1983 by the U.S. Army on the FMC M2 Bradley infantry fighting vehicle. It was a member of the Chain Gun®-family, which means it was an externally powered gun employing two internal chains to operate the action. The M242 had a dual-feed system, so that it could change from one ammunition belt to another at the flick of a switch. Although its maximum theoretical RoF was 8*, all weapons used by the U.S. military had it fixed at RoF 3*, to increase accuracy and reduce ammo consumption. It was typically fired in 3-round bursts.

The FMC M2 Bradley (1983) carried 300 ready-to-use rounds, 225 SAPHE and 75 APDS or, since 1991, APFSDSDU. Some 600 spare rounds were stored in the back of the vehicle. The DDGMC LAV-25 wheeled armored personnel carrier (1983) used by the USMC had 210 ready rounds (150 SAPHE and 60 APDS) and 420 in reserve.

The MK38 MOD 0 Sea Snake (1988) was the same gun in a naval deck mount and used on smaller U.S. Navy and Coast Guard vessels. It fired SAPHE or APDU.

The PC-1 Cyclone-class patrol boats (1993) had two mounts with 150 ready rounds per gun.

The MK44 MOD 0 Bushmaster II was nothing more than a scaled-up version of the smaller M242, chambered for the 30x173mm Oerlikon round. It even shared a large number of components with the earlier weapon; use stats of the GAU-8/A except for Ewt 324, RoF 3*, Pow 1.1kW. It fired single shots, 5-round bursts or full automatic. An APFSDS round was in service; Dam 6dx9(2). The Bushmaster II became available in 1992 and was selected by the U.S. Navy.

The Swedish-designed Hägglunds CV9030 infantry fighting vehicle (1998) adopted by Finland, Norway and Switzerland mounted the Bushmaster II and carried 160 ready rounds and 240 stowed. The General Dynamics AAAV amphibious assault vehicle (2006) adopted by the U.S. Marines was armed with the MK44-0 and carried 50 ready APFSDS and 100 ready SAPHE rounds plus 400 stowed.

General Electric GAU-12/U Equalizer, 25x137mm Oerlikon, USA, 1983

The GAU-12/U was a five-barreled hydraulic/electric rotary cannon, which, although about the same size as the M61A1 Vulcan, was actually based on the GAU-8/A. It fired the same cartridge as the M242 Bushmaster, but not usually the same rounds. Typically fired 10-round or 30-round bursts. It was license-made in Italy.

A GAU-12/U with RoF 63 was carried in a belly pack by the U.S. Marine Corps' McDonnell Douglas-BAe AV-8B Harrier II S/VTOL fighter/bomber (1989) with 300 rounds SAPHE (p. VE142). The Rockwell AC-130U Pave Spectre III gunship (1994) mounted one side-firing GAU-12/U with 3,000 rounds (p. SO89).

The DDGMC LAV-AD light armored air defense vehicle (1997) adopted by the Marines had 385 rounds ready-to-use and 600 in reserve (the ground version had RoF 30).

Hughes M230, 30x113mmB DEFA, USA, 1984

Development of this externally powered helicopter gun began in 1973. The first of the Chain Gun®-series, the M230 was an especially lightweight and compact weapon with a medium barrel. The only ammo nature commonly used was a HEDP round with alloy case.

The M230 was installed in the MDHC AH-64A Apache attack helicopter (1986). Linkless rounds were fed to it from a 1,200-round magazine. Although the gun was quite reliable, the actual weapon system as installed in the AH-64A proved to be unsatisfactory, resulting in frequent jams (Malf 16). A temporary fix was to carry only about 500 rounds of ammo (Malf Crit).

General Dynamics M301 Vulcan II, 20x102mm M50, USA, 1998

The M301 Vulcan II three-barreled helicopter gun was an update of the old 20x102mm General Electric M197. It was lightened and used ammunition with alloy cases for reduced weight.

It was installed in the Boeing-Sikorsky RAH-66A Comanche attack/scout helicopter (2002), feeding from a 500-round disintegrating belt.

The UHED Gunhed mecha (2020) mounted one gun with a 1,750-round belt.

Its predecessor, the General Electric M197 (1969), was a lightened three-barreled version of the M61A1; use the stats of the M61A1 except for Ewt 146, RoF 12/25, Pow 2.2kW/6.4kW.

The M197 was first installed in the Bell AH-1J Sea Cobra attack helicopter (1969), feeding from a 750-round belt, and also armed the AH-1S Cobra, AH-1W Super Cobra and AH-1Z King Cobra. On the AH-1-series, it fired 16-round bursts at RoF 12.

A gunpod used with, among others, the Sikorsky MH-60G Pave Hawk SpecOps helicopter (1992), held a M197 and 300 rounds (p. SO82).

CTAI CT2000, 40x225mmCTA Super Forty, France/UK, 2004

Cased Telescoped Ammunition used a large-volume, can-shaped cartridge case (as opposed to the usual bottle-shape), which completely enclosed the projectile. This made it lighter, more powerful, allowed it to be stored more space-efficiently and to be handled more easily than conventional ammo. CTA International, a joint venture between GIAT and Royal Ordnance, developed this externally powered cannon since the early 1990s for use in armored fighting vehicles. It fired 40x225mmCTA rounds with a plastic case through a very long barrel. The CT2000 had a linkless triple-feed system. Apart from standard ammunition, CTAI also designed a guided APEDS-CLGP round, which fired a saboted, armor-piercing tungsten projectile with HE charge. This laserguided 25mm dart was modified from the submunitions of the British Starstreak surface-to-air missile. Use it like a TL8 CLGP munition (p. VE112) with SALH terminal guidance (+3 to skill), with the important difference that it can only be used in direct fire.

The CT2000 was compact enough to be installed in even a relatively small fighting vehicle (in fact it had less inboard length than the M242 Bushmaster), and was retrofitted to the British GKN FV510 Warrior. The French adopted it for their new family of wheeled armored vehicles, and it was selected for the U.S. Army FSCS armored scout vehicle (2007). It remained a standard weapon until about 2050.

Mauser RMK30-2, 30x230mmCLTA, Germany, 2005

An advanced recoilless gun firing caseless telescoped ammunition through a medium barrel. It was a front-loading, externally powered revolver gun with three chambers. The recoilless operation allowed for a high-powered weapon in a very light, rotating mount. Designed in the 1990s, it was proposed for the German variant of the Eurocopter Tiger gunship and also for the KMW Wiesel microtank. It was extremely accurate, further amplified by state-of-the-art targeting electronics. The gun fired single shots or 3-round bursts.

In 2005, the German Army adopted the gun for use in an external chin mount under the Eurocopter UHT Tiger attack helicopter. The mount carried 40 linkless rounds.

Mauser MK50, 50x330mmCTA Supershot, Germany, 2006

Beginning in 1985, this externally powered gun was developed by Rheinmetall as the Rh503. It was designed from the start as being able to be converted from conventional 35x228mm Oerlikon ammo to the new plastic-cased 50x330mmCTA round by simply changing the barrel; with 35mm SAPHE-SD rounds, it had these stats: Dam 6dx6(0.5) plus 3d[4d], 1/2D 3,500, Max 8,700, Ewt 1,078, WPS 3.5. AHEAD, FAPDS and APFSDS ammo was also available, but the 35mm variant was soon outgrown by threat vehicles. In both calibers, the gun had a very long barrel and linear linkless dual feeder. Since Rheinmetall had taken over Mauser, Oerlikon and a number of other European defense companies in the 1990s, series production of the MK50 was transfered to Mauser.

The MK50 was adopted by the German Army as the main gun of its infantry fighting vehicle for the 21st century, the Marder 2. It remained a standard weapon until about 2050.

New Ammunition Types

SAPHEC, Semi-Armor Piercing, High Explosive, Concussion (Late TL6)

Developed during WWII as the Minengeschoss, this round for use against aircraft develops few fragments, but has a high explosive payload. Counts as flame attack. Available only for cannon. First available in 1940.

 

Type

Damage

Rng

WPS

CPS

Acc

 

Cr.

KE(0.5)

-

/1.5

x4

-

plus

Cr.

CxX/12,000

FAPDS, Frangible Armor Piercing, Discarding Sabot (Late TL7)

An anti-armor round with a sub-caliber penetrator which disintegrates into pyrophoric fragments after penetration. Counts as flame attack. First available in the 1990s.

 

Type

Damage

Rng

WPS

CPS

Acc

 

Cr.

1.33xKE(2)

-

/1.5

x6

-

plus

Cr.*

Fragmentation damage according to p. VE113

AHEAD, Advanced High Efficiency And Destruction (Late TL7)

A multi-mode round which can either function as a HEPF-ABF round or as SAPHE. The heavy metal fragments count as armor-piercing, i.e. [8d(2)] are treated as eight 1d(2) attacks. Its fuse is set electronically while leaving the muzzle of the gun. Available only for cannon. First available after 1991.

 

Type

Damage

Rng

WPS

CPS

Acc

 

Cr.

KE(0.5)

-

-

x8

-

plus

Exp.*

CxX/24,000 and armor-piercing fragmentation damage according to p. VE113. Fragmentation damage is doubled in HEPF-ABF mode.

APEDS, Armor Piercing, Explosive, Discarding Sabot (TL8)

An anti-armor round with a sub-caliber penetrator with explosive charge. Counts as flame attack. Available only for cannon. First available after 2000.

 

Cr.

KE(2)

x1.5

/1.5

x6

-

plus

Exp.*

CxX/64,000 and fragmentation damage according to p. VE113 divided by 2.

New Ammunition Option

Lightweight Alloy Case (Mid TL7)

Popular for aircraft guns to reduce weight. Divide WPS by 1.33 and multiply CPS by 1.33. VPS is not affected. First available in the 1970s.

Notes For The Table

Ammo: The most common ammo types are listed, in order of approximate "popularity". Note that for some weapons, these are the only ones available, while others reflect only a part of the many types produced. If in doubt, use only the ones in the chart. Note that APEX becomes available at TL6!

Malf: v(c) is short-hand for ver (crit) and means the verification must be another critical miss for the weapon to malfunction. For some modern weapons, this is still not good enough!

Damage: Mainly calculated according to pp. VE104 and VE112-113, when and if the results did not deviate too much from reality. For example, this was the case with the 30x113mmB HEDP. The rules said 2d+1(5), which penetrates a lousy average of 14.5mm of armor steel. The real thing blasts through an average of 70mm, or 11d(5). This author has opted for 5d+2(10), as it more accurately reflects the real-world performance of the round. Explosive damage was always calculated using real-world data on the explosive contents of shells. However, the Dam of KE rounds generally confirms to the rules, including the grossly inflated penetration values of some AP rounds.

1/2D and Max: Based on real-world data. The results from p. VE105 are generally too low. 1/2D (xx) means that, while accuracy suffers, Dam does not. This is generally confined to explosive rounds. Some shortened Max ranges are the result of self-destruct fuses (SD), which blow the projectile up at a given range.

RoF: The notation xx/xx means the gun has two selectable rates of fire. Usually, the lower one is for use against ground targets, the higher one for use against aircraft. Only those with a * are capable of single shots.

Ewt: Empty weight of the gun, without any mount. Taken from real-world sources. Slight differences in weight are possible, usually due to varying installations.

Cost: The costs are based on the few figures that could be secured: the HS.404 was priced at $3,500 in 1937, the M242 cost $40,000 in 1990. All other costs were based on that, but realistically, the costs are just for comparison. Weapons pricing is more often than not a matter of politics.

WPS: All taken from real-world sources.

Pow: Power requirements were taken from real-world sources except those of the M301 and RMK30-2, which had to be guesstimated.

Name

Malf

Ammo

Type

Damage

SS

Acc

1/2D

Max

RoF

Ewt

Cost

WPS

VPS

CPS

TL

Pow

Maxim QF 1-pdr Mk I

16

SAPLE

Cr

5dx2(0.5) plus 1d-3[2d]

20

8

900

3,000

5

410

$2,800

1.4

0.0093

$0.56

5

0

 

Canister

Cr

5d

20

3

100

300

1.8

0.0093

$0.28

5

 

SAPHE

Cr

5dx2(0.5) plus 1d[2d]

20

8

900

3,000

1.6

0.0093

$1.4

6

 

APEX

Cr

5dx2(2) plus 1d-3[2d]

20

8

900

3,000

1.4

0.0093

$3.5

6

Becker Kanone

crit

Solid

Cr

5dx2

18

10

800

2,800

6*

55

$2,200

0.4

0.0027

$0.2

6

0

 

SAPHE

Cr

5dx2(0.5) plus 1d-4[2d]

18

10

1,000

2,800

0.4

0.0027

$0.8

6

Oerlikon S

crit

SAPHE

Cr

6dx3(0.5) plus 1d-3[2d]

20

14

2,000

6,400

5*

135

$5,400

0.54

0.0036

$0.58

6

0

 

SAPHE-SD

Cr

6dx3(0.5) plus 1d-4[2d]

20

14

2,000

2,000

0.58

0.0036

$0.58

6

6

 

API

Cr

6dx3(2)

20

14

2,000

6,400

0.58

0.0036

$1.16

6

Bofors m/36

crit

HE

Exp*

3d[4d]

20

14

(4,000)

11,200

2*

580

$7,700

4.6

0.031

$4.6

6

0

 

HE-SD

Exp*

3d[4d]

20

14

3,700

3,700

4.6

0.031

$4.6

6

 

AP

Cr

6dx6(2)

20

14

4,000

9,600

4.6

0.031

$6.9

6

Mauser MG151/20

crit

SAPHE

Cr

5dx3(0.5) plus 1d-3[2d]

20

13

1,000

5,000

12

92

$3,700

0.45

0.003

$0.45

6

neg

 

SAPHEC-SD

Cr

5dx3(0.5) plus 1d-2

20

13

1,000

2,300

0.4

0.003

$0.9

6

 

AP

Cr

5dx3(2)

20

13

1,000

5,000

0.45

0.003

$0.68

6

Tulamash VYa-23

crit

API

Cr

7dx3(2)

20

14

2,300

7,800

10

151

$6,000

1.0

0.0067

$2

6

0

 

SAPHE

Cr

7dx3(0.5) plus 1d-1[2d]

20

14

2,300

7,800

1.0

0.0067

$1

6

Rheinmetall-Borsig BK3.7

crit

APCR

Cr

6dx5(2)

25

12

2,000

6,000

3*

598

$8,000

2.4

0.021

$8

6

0

 

APEX

Cr

6dx4(2) plus 3d+2[4d]

25

12

2,000

6,000

3.2

0.021

$8

6

 

SAPHEC-SD

Cr

6dx4(0.5) plus 3d+2

25

12

2,000

3,200

3.1

0.021

$6.4

6

Rheinmetall-Borsig MK108

crit

SAPHEC

Cr

5dx3(0.5) plus 2d+2

20

10

600

3,000

10

128

$2,500

1.06

0.007

$2.12

6

neg

Mauser MK213

crit

SAPHEC

Cr

5dx3(0.5) plus 3d+1

20

13

1,500

5,000

19

165

$6,600

1.1

0.0073

$2.2

6

neg

 

APEX

Cr

5dx3(2) plus 2d+1[2d]

20

13

1,500

5,000

1.1

0.0073

$2.75

6

DEFA Mle 552

crit

SAPHE-SD

Cr

6dx3(0.5) plus 1d-1[2d]

20

14

1,500

3,300

21

180

$29,000

1.08

0.0072

$4.32

7

neg

 

SAPHEC-SD

Cr

6dx3(0.5) plus 2d-1

20

14

1,500

3,300

0.97

0.0072

$8.64

7

 

API

Cr

6dx3(2)

20

14

1,500

5,000

1.08

0.0072

$8.64

/

Tulamash GSh-23

crit

SAPHE

Cr

6dx3(0.5) plus 1d-2[2d]

20

12

1,500

7,000

56

111

$18,000

0.77

0.0051

$3.08

7

neg

 

API

Cr

6dx3(2)

20

12

1,500

7,000

0.77

0.0051

$6.16

7

 

Shrapnel

Cr

9d

20

12

1,500

3,000

0.77

0.0051

$4.62

7

GE M61A1 Vulcan

v(c)

SAPHE

Cr

6dx3(0.5) plus 1d-4[2d]

20

15

2,000

6,000

66/100

252

$40,000

0.57

0.0038

$2.3

7

17kW/26kW

 

API

Cr

6dx3(2)

20

15

2,000

6,000

0.57

0.0038

$4.6

7

 

APEX

Cr

6dx3(2) plus 1d-4[2d]

20

15

2,000

6,000

0.57

0.0038

$5.7

/

Ford M129

ver

HE

Exp*

3d[3d]

20

8

1,600

2,200

6

45

$12,000

0.75

0.005

$3

7

1.1kW

OTO Melara 76/62 Compatto

crit

HE

Exp*

6dx4[6d]

25

16

(8,700)

17,800

1.5*

3,295

$175,000

27.5

0.18

$110

7

44kW

 

HEPF

Exp*

6dx4[6d]

25

16

(8,700)

17,800

26.8

0.18

$275

7

 

SAPHE

Cr

6dx11(0.5) plus 6dx3[6d]

25

16

8,700

17,800

27.5

0.18

$110

7

 

APFSDS

Cr

6dx26(2)

25

17

3,500

26,000

20.0

0.18

$440

/

GE GAU-8/A Avenger

v(c)

APDU

Cr

6dx6(3)

25

15

3,000

9,000

35/70

620

$75,000

1.6

0.01

$24

7

29kW/57kW

 

SAPHE

Cr

6dx5(0.5) plus 2d-1[2d]

25

15

3,000

9,000

1.5

0.01

$8

7

 

APDS

Cr

6dx8(2)

25

15

4,000

13,500

1.2

0.01

$20

7

Tulamash 2A42

crit

SAPHE-SD

Cr

6dx5(0.5) plus 2d[2d]

20

14

3,000

4,000

4*/9*

253

$27,000

1.9

0.013

$7.6

7

neg

 

AP

Cr

6dx5(2)

20

14

3,000

8,000

1.9

0.013

$11.4

7

 

APEX

Cr

6dx5(2) plus 2d[2d]

20

14

3,000

8,000

1.9

0.013

$11.4

7

 

APDS

Cr

6dx8(2)

20

14

4,000

12,000

1.7

0.013

$19

/

Mauser BK27

ver

SAPHE

Cr

7dx4(0.5) plus 1d+1[2d]

20

15

3,000

8,000

16/28

220

$25,000

1.2

0.008

$4.8

7

neg

 

APEX

Cr

7dx4(2) plus 1d[2d]

20

15

3,000

8,000

1.2

0.008

$12

7

 

FAPDS

Cr*

6dx6(2) plus [2d]

20

15

4,000

12,000

0.8

0.008

$14.4

7

 

HEDP

Exp*

5d+2(10) plus 1d[2d]

20

15

3,000

8,000

1.2

0.008

$7.2

7

Izhmash GSh-301

crit

SAPHE-SD

Cr

6dx5(0.5) plus 2d[2d]

20

14

2,500

4,000

27

101

$16,000

1.9

0.013

$7.6

7

neg

 

APEX

Cr

6dx5(2) plus 2d[2d]

20

14

2,500

8,000

1.9

0.013

$11.4

/

Hughes M242 Bushmaster

ver

SAPHE

Cr

6dx4(0.5) plus 1d[2d]

20

15

2,500

7,500

3* or 8*

244

$40,000

1.1

0.0073

$4.4

7

2.2kW or 6kW

 

APDS

Cr

6dx7(2)

20

15

2,500

10,500

1.0

0.0073

$11

7

 

APFSDSDU

Cr

6dx7(3)

20

16

3,000

17,000

1.0

0.0073

$26

7

 

APDU

Cr

6dx5(3)

20

15

2,500

7,500

1.1

0.0073

$13.2

7

GE GAU-12/U Equalizer

v(c)

SAPHE

Cr

6dx4(0.5) plus 1d[2d]

20

15

2,500

7,500

30/60

270

$43,000

1.1

0.0073

$4.4

7

5.5kW/10kW

 

APEX

Cr

6dx4(2) plus 1d[2d]

20

15

2,500

7,500

1.1

0.0073

$8.8

/

Hughes M230

ver

HEDP

Exp*

5d+2(10) plus 1d[2d]

20

14

2,000

4,400

10

123

$30,000

0.77

0.0072

$6.1

7

2.2kW

GD M301 Vulcan II

v(c)

APEX

Cr

6dx3(2) plus 1d-2[2d]

20

15

2,000

6,000

12/25

76

$34,000

0.4

0.0038

$7.8

7

1.6kW/4.4kW

CTAI CT2000

ver

APFSDS

Cr

6dx11(2)

25

16

4,500

18,000

6*

725

$60,000

4.0

0.015

$110

7

9kW

 

AHEAD

Cr

6dx6(0.5) plus 3d[4d(2)]

25

15

3,500

9,000

4.8

0.015

$110

7

 

APEDS-CLGP

Cr

6dx6(2) plus 1d[2d]

25

15

4,000

12,000

4.2

0.015

$833

8

Mauser RMK30-2

ver

APEX

Cr

7dx4(2) plus 1d+2[2d]

20

16

3,000

7,000

6*

220

$40,000

1.1

0.0075

$22

8

2.3kW

Mauser MK50

ver

APFSDS

Cr

6dx13(2)

25

16

5,000

20,000

6*

1,133

$90,000

4.4

0.017

$120

7

8kW

 

AHEAD

Cr

6dx7(0.5) plus 5d[4d(2)]

25

15

4,000

12,000

5.0

0.017

$120

7

 

HEPF

Exp*

8d[4d]

25

15

(4,000)

12,000

5.0

0.017

$150

7

 

APEDS

Cr

6dx7(2) plus 2d[2d]

25

15

5,000

18,000

4.5

0.017

$90

7

Selected References




Article publication date: May 11, 2001


Copyright © 2001 by Steve Jackson Games. All rights reserved. Pyramid subscribers are permitted to read this article online, or download it and print out a single hardcopy for personal use. Copying this text to any other online system or BBS, or making more than one hardcopy, is strictly prohibited. So please don't. And if you encounter copies of this article elsewhere on the web, please report it to webmaster@sjgames.com.