TheMk44 Bushmaster II is a30 mmchain gun manufactured byNorthrop Grumman. It is a derivative of the25 mmM242 Bushmaster, and uses 70% of the same parts as the M242 while increasing the firepower by as much as 50% with the 20% increase in caliber size. The barrel ischromium-plated for extended life. The gun uses standardGAU-8 Avenger ammunition that is available inAPI (Armor-Piercing Incendiary),HEI (High-Explosive Incendiary) andAPFSDS-T (Armor-Piercing Fin-Stabilized Discarding Sabot-Tracer) variants.

Mk44 Bushmaster II
FinnishCV 9030 with Mk44
Type	Chain gunautocannon
Service history
In service	2007–present
Used by	Seeusers
Production history
Designer	Alliant Techsystems
Manufacturer	Northrop Grumman
Specifications
Mass	344 lb (160 kg)
Length	134.05 inches (3,405 mm)
Barrel length	94.88 inches (2,410 mm)
Width	13.5 inches (340 mm)
Height	15.43 inches (392 mm)
Shell	30×173mm 40×180mm
Caliber	30 millimetres (1.18 in) caliber 40 millimetres (1.57 in) caliber
Rate of fire	100/200 rounds per minute
Muzzle velocity	1,080 metres per second (3,500 ft/s) (HEI-T ammunition)
Effective firing range	3,000 metres (9,800 ft) land appl. 5,100 metres (16,700 ft) naval appl.

The gun can be converted to a caliber of 40×180 mm, which involves changing the barrel and a few key parts, to use the SuperShot 40 cartridge. It can also be converted to use the 30×170 mmRARDEN cartridge.

The Bushmaster II is the standard primary armament of theBionix-II AFV currently in service with theSingapore Army, theKTO Rosomak inPolish service, and theCV90 AFVs inFinnish,Norwegian andSwiss service. Although theUnited States Air Force selected this cannon to replace the25 mm GAU-12 Equalizer andBofors 40 mm Automatic Gun L/60 guns on its fleet ofAC-130U gunships in 2007, this plan was later canceled.^[1] TheUnited States Marine Corps' cancelledExpeditionary Fighting Vehicle, was expected to be armed with this cannon as well. SomeUnited States Navy vessels, such as the newSan Antonio-classamphibious transport dock are armed with the Bushmaster II for surface threat defense.

The Bushmaster II cannon is used in theDS30M Mark 2 Automated Small Calibre Gun (ASCG) point defense system that is fitted to theRoyal Navy'sType 23 frigates.^[2]

The Bushmaster II cannon is also used in the Turkish madeAselsan SMASH stabilizedweapon station.^[3]

The USAF had experimented with installing Bushmaster II cannons on theirAC-130U gunships in place of theGAU-12 andBofors 40 mm cannons. On 11 August 2008, the effort was canceled because of problems with the Bushmaster's accuracy in tests "at the altitude we were employing it." There were also schedule considerations that drove the decision.^[4] On 9 July 2012, the Air Force type classified a new version of the Bushmaster called theGAU-23/A. The cannon will be used on theAC-130W and theAC-130J gunships.^[5]

TheU.S. Navy uses the Mk44 Bushmaster II in theMk 46 Mod 2 Gun Weapon System (GWS). The GWS is produced byGeneral Dynamics to give warships protection against small, high-speed surface craft. A Mk 46 turret consists of the 30 mm chain gun, aforward looking infrared (FLIR) sensor, a low light television camera, and alaser rangefinder. The guns fire at 200 rounds per minute and are fed by a 400-round magazine through 200-round dual feeds. Effective range is 2,200 yd (2,000 m) for full-caliber high-explosive or armor-piercing ammunition, which can be extended when using sub-caliber rounds. The Mk 46 GWS is permanently installed on theSan Antonio-class amphibious transport dock and can be installed onFreedom andIndependence-classlittoral combat ships as part of the surface warfare (SuW) package.^[6][7] In 2012, the Navy decided to replace theMk 110 57 mm cannons onZumwalt-class destroyers with the Mk 46 GWS.^[8]

Orbital ATK developed a modified version of the Bushmaster II, known as the Mk44 STRETCH, which can fire the 30x173 mm Mk310 PABM-Tairburst round.^[9][10]

In January 2020,Northrop Grumman revealed the development ofproximityairburst rounds for the LCS' 30 mm gun modules to destroy smallunmanned aerial vehicles (UAVs). Since the modules feature dual feeders, different types of rounds could be fed for different targets.^[11]

In October 2023, the UK announced it would be delivering the Terrahawk Paladin to Ukraine as part of assistance during theRussian invasion of Ukraine. The Terrahawk Paladin is made by MSI Defence Systems (MSI-DS) as a land-based version of theSeahawk. It is a static Very Short-Range Air Defense (VSHORAD) Counter Unmanned Aerial Systems (C-UAS) system that can be deployed off a truck. The system combines radars, EO/IR cameras, and laser rangefinders with a 30 mm Mk44 Bushmaster II chain gun with 240 rounds of airburst munitions capable of engaging small UAS out to 2 km (1.2 mi).^[12][13][14]

The XM813 Bushmaster is based on the Mk44 and is offered as an upgrade forU.S. ArmyM1126 Stryker andM2 Bradley vehicles, as well as having been a contender to be the primary armament of theGround Combat Vehicle. The improvements include a 25.4 mm (1.00 in) longer barrel, integral mount to increase first round hit probability by up to 10%, a dual recoil system to enhance accuracy to help cope with future hotter propellants, and a Meggitt linkless dual feed ammunition system.^[15] The 30 mm chain gun can fireMk310 ProgrammableAir Burst Munition rounds to attack targets indefilade. TheUnited States Army Research, Development and Engineering Command helped enhance the XM813 mainly for safety and turret integration. By changing five parts, the gun caliber can be increased to 40 mm. As of November 2013, the XM813 was being tested atAberdeen Proving Ground over three months to ensure reliability levels of 40,000 mean rounds between failures. Long-term plans are to equip vehicles with theBushmaster III 35mm/50mm cannon.^[16][17]

The XM813 was demonstrated in September 2014 at the ARDEC Digital Multi-Purpose Range Complex. The gun was mounted on aBradley Fighting Vehicle and fired at targets up to 1,500 metres (0.93 mi) away. An enhanced fire control system improves long-range accuracy to kill targets with fewer bursts, sometimes as few as two or three rounds instead of 10. The XM813 30 mm cannon is intended to replace theM242 Bushmaster 25 mm chain gun, and can be mounted on vehicles other than the Bradley. Two capabilities not demonstrated were its linkless ammunition with airburst capabilities; airburst rounds increase lethality by enabling engagement of targets in defilade when they would otherwise only be suppressed by fire.^[18]

In early 2015, the U.S. Army approved an upgrade for 81Stryker vehicles of aStryker Brigade Combat Team deployed in Europe to be upgunned with the Mk44 30 mm Bushmaster cannon to increase their lethality against other light armored vehicles used by Russia in the theater.^[19] The cannons will be installed by 2018, and may be the first step in adding the Bushmaster to the entire active fleet of about 1,000 Strykers;^[20] the XM813 variant will be used with the Strykers.^[21] The XM813 has a demonstrated firing ability out to 3,000 metres (1.9 mi) for precision firing, nearly twice as far as theM2 12.7 mm caliber machine gun that has a maximum effective range of 1,830 metres (1.14 mi) as an area suppression weapon. The first upgunned Stryker, known as the "Dragoon" for the2nd Cavalry Regiment the vehicles will be part of, was delivered in October 2016,^[22][23] and the first Infantry Carrier Vehicle - Dragoon (ICVD) was delivered to the 2CR in Germany in December 2017.^[24]

The ATK MK44-ABM variant of the Bushmaster was selected in 2018 by theSpanish Army to equip theTizona turret of the Line version (IFV) of theDragón IFV, the replacement of thePegaso BMR.^[25]

  Argentina

• Navy:Gowind-class corvette

  Australia

• Army:AS21 Redback (EOS T-2000 turret)^[26]

  Belgium

• Army:Piranha IIIC DF30

  Botswana

• Army:Mowag Piranha IIIC^[27]

  Brazil

• Army:VBTP-MR Guarani^[28]
• Navy:Amazonas-class corvette,NAMAtlântico aircraft carrier

  Bulgaria

• Army: XM1296Stryker Dragoon^[29]

  Croatia

• Army:Patria AMV (Elbit UT30 Mk2 turret)

  Czech Republic

• Army:Pandur II CZ,^[30]CV9030CZ^[31]

  Finland

• Army:CV9030FIN

  Ghana

• Army:Sentinel II 8×8,Sentinel II 6×6 (with Elbit UT30 turret)^[32]

  Indonesia

• Army:Pindad Cobra IFV (ARES UT30 MK2 turret)^[33]
• Navy:Mamuju-class,Pari-class patrol vessel,Pollux-class research vessel andClurit-class fast attack craft
• Coast Guard:Tanjung Datu-class patrol vessel,Pulau Nipah-class patrol vessel andBintang Laut-class patrol vessel

  Japan

• Coast Guard:Hateruma-class patrol vessels,Kunigami-class patrol vessels (later ships), &Iwami-class patrol vessels
• Common tactical wheeled vehicle:
  • ICV -Infantry combat vehicle [ja]
  • RCV -Reconnaissance combat vehicle [ja]

  Iraq

• Navy:Swiftshipspatrol boats

  Ireland

• Army:Mowag Piranha IIIH^[34]

  Italy

• Army:Freccia EVO (Combat and Reconnaissance variants)^[35]

  Lithuania

• Army:Vilkas (Orbital ATK Mk44S variant)^[36][37]

  Malaysia

• Malaysian Navy:Maharaja Lela-class frigate

  Netherlands

• Navy:Holland-class offshore patrol vessel andKarel Doorman-class support ship

  Norway

• Army:CV9030N

  Oman

• Navy:Khareef-classcorvettes

  Philippines

• Navy:Jose Rizal-class frigates andShaldag Mk.V missile fast attack craft

  Poland

• Army:Rosomak (Hitfist andZSSW-30),^[38][39]Borsuk, CBWP Heavy IFV^[40]

  Romania

• Army:Mowag Piranha V^[41]

  Saudi Arabia

• National Guard:LAV-700 IFV (CMCT turret)^[42][43]

  Singapore

• Army:Bionix II,Hunter AFV

  Spain

• Army:Piranha V - Dragon (219 VCR, 14 VCR-PC, 58VEC)^[44]

   Switzerland

• Army:CV9030CH

  Taiwan

• Army:CM-34 (IFV variant)^[45]
• Military police:CM-34 (IFV variant)^[46]

  Thailand

• Navy:Tachin-class frigate,Naresuan-class frigate,Krabi-class offshore patrol vessel,Leamsing-class patrol craft (gun),T.991-class coastal patrol craft,T.994-class coastal patrol craft,Angthong-class amphibious transport dock andLadya-class mine countermeasure vessel

  Ukraine

• Army: XM1296Stryker Dragoon,KTO Rosomak (Hitfist-30P)^[47]

  United Kingdom

• Navy:River-class Batch II offshore patrol vessels,Type 23 frigate,Type 45 destroyer

  United States

• Army: XM1296Stryker Dragoon
• USMC: ACV (Iveco SuperAV with Kongsberg MCT-30 turret)
• Navy:San Antonio-class transport ship,Littoral combat ship andZumwalt-class destroyer
• Air Force:AC-130W, AC-130J (GAU-23/A)
• Coast Guard:Polar Security Cutter^[48]

• Bushmaster 25 mm chain gun
• Bushmaster III 35/50 mm chain gun
• Bushmaster IV 40 mm chain gun
• 30mm Shipunov 2A42—Soviet/Russian autocannon
• 30mm L21A1 RARDEN—British autocannon
• Future Combat Systems Infantry Carrier Vehicle

• http://www.atk.com/Products/documents/108279_01_Mk44.pdf^{[dead link]}

Notes

• Alliant Techsystems (ATK) Mk44 Bushmaster Automatic Cannon Fact Sheet
• Alliant Techsystems (ATK) GAU-23 Bushmaster Automatic Cannon Fact Sheet
• 30mm Bushmaster II on NavWeap.Com
• Mk44 Bushmaster II 30mm on GlobalSecurity.Org