M109 howitzer

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"M109" redirects here. For other uses, see M109 (disambiguation).

The **M109** is an American 155 mm turreted self-propelled howitzer, first introduced in the early 1960s to replace the M44. It has been upgraded a number of times, most recently to the **M109A7**. The M109 family is the most common Western indirect-fire support weapon of maneuver brigades of armored and mechanized infantry divisions.

The M109 has a crew of four: the section chief/commander, the driver, the gunner, and the ammunition handler/loader. The chief or gunner aims the cannon left or right (deflection) and up and down (quadrant).

The British Army replaced its M109s with the AS-90. Several European armed forces have or are currently replacing older M109s with the German PzH 2000. Upgrades to the M109 were introduced by the U.S. (see variants below) and by Switzerland (KAWEST). With the cancellation of the U.S. Crusader and Non-Line-of-Sight Cannon, the M109A6 ("Paladin") will likely remain the principal self-propelled howitzer for the U.S. until the new M1299 enters service.

## History

The M109 was the medium variant of a U.S. program to adopt a common chassis for its self-propelled artillery units. The light version, the M108 Howitzer, was phased out during the Vietnam War, but many were rebuilt as M109s.

The M109 saw its combat debut in Vietnam. Israel used the M109 against Egypt in the 1973 Yom Kippur War and in the 1982 and 2006 Lebanon Wars. Iran used the M109 in the Iran–Iraq War in the 1980s. The M109 saw service with the British, Egyptian and Saudi Arabian Armies in the 1991 Gulf War. The M109 also saw service with the U.S. Army in the Gulf War, as well as in the Iraq War from 2003 to 2011.

Upgrades to the cannon, ammunition, fire control, survivability, and other electronics systems over the design's lifespan have expanded the system's capabilities, including tactical nuclear projectiles, guided projectiles (Copperhead), Rocket Assisted Projectiles (RAP), FAmily of SCAtterable Mines (FASCAM), and cluster munitions (the Dual-Purpose Improved Conventional Munition, DPICM)

## Design

The M109 was developed by the Ground System Division of United Defense LP (now BAE Systems Land and Armaments).

### Armament

* Primary: M126 Cannon (or M126A1) 155 mm Howitzer (M109), M185 Cannon 155 mm Howitzer (A1/A2/A3/A4), or M284 Cannon 155 mm Howitzer (A5/A6)
* Secondary: .50 caliber (12.7 mm) M2 machine gun, Mk 19 Mod 3 40 mm Automatic Grenade Launcher, 7.62 mm M60, M240 machine gun or L4 machine gun

#### Hypervelocity Projectile (HVP)[edit]

In January 2016, the U.S. Army test-fired hypervelocity projectiles originally designed for use by U.S. Navy electromagnetic railguns and found that they significantly increased the gun's range. The Army is looking into using the M109 Paladin firing the HVP for ballistic missile defense, as traditional missile interceptors are expensive and gun-based missile defense used for point defense would use artillery at a much lower cost per round. The HVP is capable of being fired out to 50 nautical miles (58 mi; 93 km) from a conventional cannon. It weighs 68 lb (31 kg) with a 46 lb (21 kg) flight body containing its guidance and warhead—less powerful, but more agile to hit small, high-speed targets. Modifications will be needed for the Paladin to effectively shoot the HVP, possibly including different propellant to achieve higher velocities, automated reloading systems to fire quickly enough to defeat salvo launches, improved barrel life, and a new fire control and sensor system. During a test of the Air Force's Advanced Battle Management System (ABMS) on 3 September 2020, an HVP fired from an Army Paladin howitzer successfully intercepted a BQM-167 target drone simulating a cruise missile.

### M109

First produced in 1963. It had a 23 caliber 155 mm M126 Cannon in an M127 Mount, and carried 28 rounds of 155 mm ammunition. It was also armed with a .50cal M2HB machine gun with 500 rounds of ammunition. Easily identified by its short barrel and a double baffle muzzle brake with a large fume extractor just behind it. Maximum range of 14,600 meters.

### M109A1

Replaced the M126 Cannon with a 39 caliber M185 Cannon, featuring a longer barrel while increasing maximum range to 18,100 meters.

### M109A2

Incorporated 27 Reliability, Availability, and Maintainability (RAM) mid-life improvements. Most notably, the long-barreled 155 mm M185 Cannon in the new M178 gun mount, ballistic protection for the panoramic telescope, counterbalanced travel lock, and the ability to mount the M140 bore sight alignment device. Stowage of 155mm rounds increased from 28 to 36 rounds; .50cal ammunition remained at 500 rounds. During M109A2 production, a slightly simplified version was also produced for export. This had minor internal changes and deleted the hull flotation feature. These were designated **M109A1B.**

### M109A3 and M109A3B

M109A1s and M109A1Bs were rebuilt to M109A2 standard respectively. Some A3s feature three contact arm assemblies, while all A2s have five.

### M109A4

M109A2s and M109A3s improved with Nuclear, Biological, and Chemical / Reliability, Availability, and Maintainability (NBC/RAM) improvements, including air purifiers, heaters, and Mission Oriented Protective Posture (MOPP) (protective) gear.

The traversing mechanism's clutch is hydraulic, as compared to the electric mechanism on previous M109s, and features a manual override in the event of an electrical failure. The M109A4 also added an additional hydraulic filter, for a total of two. Also included is an improvement to the engine starting equipment, greatly improving the ability to start in an emergency.

Ammunition amounts remain the same as two previous models.

### M109A5

Replaces the 155 mm M185 Cannon in an M178 Mount with a 39-caliber 155 mm M284 Cannon in an M182 Mount, giving the A5 a maximum range of 22,000 meters with unassisted projectiles and 30,000 meters with Rocket Assisted Projectile (RAP) rounds. The vehicle can carry 36 complete rounds of ammunition and has a 440 hp engine instead of the standard 405 hp engine.

### M109A5+

Various manufacturers have upgraded the fire control and other components of the M109A5. BAE Systems in York PA recently delivered 12 M109A5+ vehicles to Chile and 40 M109A5+ vehicles for Brazil.

### M109A6 "Paladin"

Overall product improvement in the areas of survivability, RAM, and armament. This includes increased armor, a redesigned internal arrangement for safer ammunition and equipment storage, engine and suspension upgrades, and product improvement of the M284 Cannon and M182A1 Mount. The greatest difference is the integration of an inertial navigation system, sensors detecting the weapons' lay, automation, and an encrypted digital communication system, which utilizes computer controlled frequency hopping to avoid enemy electronic warfare and allow the howitzer to send grid location and altitude to the battery Fire Direction Center (FDC) . The battery FDCs in turn coordinate fires through a battalion or higher FDC. This allows the Paladin to halt from the move and fire within 30 seconds with an accuracy equivalent to the previous models when properly emplaced, laid, and safed—a process that required several minutes under the best of circumstances. Tactically, this improves the system's survivability by allowing the battery to operate dispersed by pairs across the countryside and allowing the howitzer to quickly displace between salvos, or if attacked by indirect fire, aircraft, or ground forces.

Ammunition storage is increased from 36 to 39 155 mm rounds.

US Army received first Paladin in 1994 and last of 950 ordered in 1999.

### M109 "KAWEST"

This Swiss improved version produced by Ruag incorporates a new Swiss-designed L47 155 mm gun with an increased firing range of up to 36 km. It features inertial navigation system coupled with a new gun-laying system and more ammunition storage (40 rounds, 64 charges). The KAWEST (lit. *Kampfwertsteigerung* = upgrade of combat capabilities) requires only 6 crew members instead of 8, and is able to fire 3-round bursts within 15 seconds or maintain a constant firing rate of over one round per minute.

Upgraded Swiss PzHb (Panzerhaubitze) 79 and 88 (M109A1) are known as respectively **PzHb 79/95** and **PzHb 88/95**.[*citation needed*]

### M109L52

Jointly developed by the Dutch firm RDM and the German firm Rheinmetall, the M109L52 was first revealed in 2002. The main improvement was replacing the M126 series gun with the longer 52-caliber cannon from the PzH 2000, thus the MTLS ammunition of the PzH 2000 can be used. In addition, improvements to the loading system were made. This resulted in an increase of the rate of fire to 9–10 rds/min from the original 3 rds/min, and this high rate of fire can be sustained for up to 2 minutes. A total of 35 rounds can be carried.

### M109A3GNM

The latest version in service with the Norwegian Army's Artilleribataljonen. 126 M109Gs were acquired from West Germany between 1969 and 1971. They were then upgraded to the M109A3GN configuration during the latter half of the 1980s. In 2006, there were still 56 M109A3GNs in the Army's inventory, meaning that at least 70 SPGs had been scrapped after the end of the Cold War. 14 of the M109A3GNs received additional upgrades in 2007, and were designated M109A3GNM. The upgrade includes, among other things, new intercom and new navigation and positioning systems. In 2020, both the 14 units with "A3GNM" upgrades and the rest of the units still having "A3GN" specs were put in storage, as all of the new Korean K9 Thunder units had been delivered. In May 2022, Norway donated 22 "A3GN" to Ukraine.

### K55/K55A1

K55/K55A1 are South Korean variants of the M109A2, originally named KM109A2 with additional domestic augmentations, 1,040 units were license-produced by Samsung Aerospace Industries from 1985 to 1997. They are fitted with M185 155 mm 39 caliber gun, NBC protection, automatic fire extinguishing system, and a modified ammunition reception module for K56 automatic ammunition resupply vehicle. The Performance Improvement Program variant, K55A1, is a complete domestic overhaul of the K55 which is further augmented by Samsung Thales with modern digital ballistic computers, multifunctional data display and controllers, GPS navigation and target acquisition system, wireless datalink equipment, and upgraded fire control storage battery and power supply unit, to closely match the US military's modernization of the Paladin into next-generation standard. Many improved technologies of the South Korean K9 Thunder were retrofitted on the K55A1.

### M109A7

The newest M109 version for U.S. service is the M109A7, formerly known as the M109A6 Paladin Integrated Management (PIM). The M109A7 shares common chassis components with the Bradley Fighting Vehicle (BFV) such as the engine, transmission, and tracks. This creates commonality with other systems and maximizes cost-savings in production, parts inventory, and maintenance personnel. The M109A7's onboard power systems harness technologies originally developed for the Non-Line-of-Sight Cannon; the electric drive is faster than the previous hydraulic system, and the automatic rammer more consistently rams the round into the gun for consistent velocities and better accuracy. It features a 600-volt onboard power system to accommodate additional armor and future networking technologies as they become ready. The M109A7 can sustain a one-round per-minute rate of fire and a maximum rate of fire of four rounds per-minute. Weighing 78,000 lb (35,000 kg), the M109A7 is 10,000 lb (4,500 kg) heavier than its predecessor, and it has the capacity to grow to 110,000 lb (50,000 kg). Even with the weight increase, the M109A7 can travel faster than previous versions at 38 mph (61 km/h) and is more maneuverable than a BFV.

Prototypes of the vehicle underwent government testing in preparation for a Low-Rate Initial Production (LRIP) decision. The testing included RAM, mission and ballistic hull and turret testing. The M109A7 was slated to begin LRIP by 2013. The U.S. Army planned on procuring a fleet of 580 sets of M109A7 howitzers and M992A3 Field Artillery Ammunition Support Vehicles (FAASVs).

In October 2013, the Defense Acquisition Board approved the decision to start M109A7 production. The FY 2014 budget called for $340.8 million in Paladin funding, which would be two dozen vehicle sets at $14.4 million per vehicle. The Army plans to buy 133 vehicles in 66 one-half vehicle sets starting in 2014, although one M109A7 howitzer and two supporting M992A3 ammunition carriers will be destroyed during tests. A Full-Rate Production (FRP) decision planned for February 2017. On 31 October 2013, BAE received a $668 million contract to begin LRIP of the M109A7. The first M109A6 and M992A2 vehicles were disassembled and reassembled to M109A7 and M992A3 standard as part of LRIP beginning in summer 2014. LRIP deliveries began in April 2015. The contract for FRP was signed in December 2017 with 48 vehicles slated for construction. The Army plans to upgrade 689 Paladins to A7-standard.

The Army is looking to increase the capabilities of the M109A7. By introducing the new XM1113 rocket-assisted projectile (RAP), it can reach 40 km (25 mi) from the current 39-caliber barrel, and a planned barrel extension to 58-caliber can increase its range to 70 km (43 mi). An additional XM1113 improvement over the legacy RAP round is the replacement of the high explosive, TNT, with an insensitive munition that is less volatile and less prone to unplanned detonation.[*citation needed*] The Army is also working on an autoloader to increase sustained rate of fire to 6–10 rounds per minute. Another part of the effort is the use of a new supercharged propellant to fire the shells, which required redesigning the howitzer to handle higher pressures. These improvements are being developed under the Extended Range Cannon Artillery (ERCA) program, which upgrade the design so much it was re-designated the M1299; one battalion of vehicles is planned to begin a year-long operational assessment in 2023, and the autoloader is planned to be ready in 2025.

## Derivatives

### M992[edit]

The M992 Field Artillery Ammunition Support Vehicle (FAASV) is built on the chassis of the M109. It replaced the M548. Unlike the M548, it is armored. This ammunition vehicle has no turret, but has a taller superstructure to store 93 rounds and an equivalent number of powders and primers.

This vehicle is fitted with a Halon fire suppression system and a weapons mount similar to that on the M109 turret, usually mounting a Mk 19 grenade launcher for local defense against infantry and light armored vehicles.

The vehicle also contains a 2-stroke diesel powered auxiliary power unit that can power all non-automotive energy requirements on the FAASV and on the M109.

### Training systems

The US Army uses the Fire Support Combined Arms Tactical Trainer (FSCATT) in two versions for initial and sustainment training of the M109A6 and M109A5. The system uses an actual surplus turret and a simulated ammunition system.

The Swiss Army uses a highly advanced KAWEST trainer from Van Halteren Metaal of the Netherlands.

The Dutch, Belgian, Thai, and Israeli Armies have various configurations of the Van Halteren Metaal M109 Howitzer Crew Trainer (HCT).

The US Army PEO STRI had a program called M109A7 Howitzer Crew Trainer (HCT). The plan was to procure 16 systems beginning in the 3rd Quarter of FY 20.

## Successors

The U.S. Army sought to replace the M109 with the XM2001 Crusader, initially part of the Armored Systems Modernization program. The program was canceled in 2002 amid criticism that the program was not in line with the Army's long-term plans for lighter armored brigades. Funding was redirected to the Future Combat Systems Manned Ground Vehicles program, which produced the 18-ton XM1203 Non-Line-of-Sight Cannon as the program's lead effort. The Pentagon terminated the MGV program in 2009 due to concerns over its affordability. The U.S. Army's M1299 howitzer is planned to be completed in 2021 and will undergo operational assessment in 2023.

### Current operators

#### M109A1

* Djibouti: 10
* Ethiopia: 17
* Greece: 51 A1B
* Iran: 440
* Morocco: 44 M109A1B
* Oman: 15 A0
* Peru: 12
* Switzerland: 224 (upgraded to M109 KAWEST)
* United Arab Emirates: 40 (from Switzerland)

#### M109A2/A3

* Brazil: 40 A3 (former Belgian)
* Greece: 84 A2, 50 A3GEA1, 223 A3GEA2
* Egypt: 400 A2
* Jordan: 356 A2/A2-90 (121 M109A2-90 purchased from Netherlands)
* Lebanon: 12 A3
* Morocco: 78 M109A2, 22 M109A3 and 40 M-109L47
* Pakistan: 785 A2 in service with the Pakistan Army. Being upgraded to M109A5 standard.
* Saudi Arabia: 60 A2s are currently being upgraded to A5s (2010)
* Spain: 6 (Spanish Marines)
* Tunisia: 19–20 A2 (former Belgian)
* Ukraine: 22 A3GN (donated by Norway)

#### M109A2/A5

* Austria: 33 A2/A5Ö
* Latvia: 65 A5Ö
* Republic of China (Taiwan): 197

#### M109A4

* Indonesia: 36 units M109A4-BE bought from Belgium
* Morocco: 4 M109A4
* Ukraine: Unknown previously owned by Belgium, bought, refurbished and donated by the UK.

#### M109A5

* Brazil: 96 A5/A5+ More 56 surplus U.S. Army, to be upgraded to M109A5+, contract awarded to BAE Systems.
* Chile: 48 (24 from Switzerland, upgraded to M-109 KAWEST, 12 A3 and 12 A5+ Upgrade to similar Paladin configuration)
* Egypt: 201
* Saudi Arabia: 36
* Iraq: 90
* Israel: 600
* Pakistan:
* Portugal : 18 since 2002 (Portuguese Army). 6 of these vehicles were M109A2/A3 upgraded to A5 variant. This variant replaced the previous 6 M109A2 operated by the Portuguese Army.
* Thailand: 20
* Greece: 12
* Spain: 96 (Spanish Army)
* Morocco: 70
* Lebanon: 74 TBD
* Republic of China (Taiwan): 28

#### M109A6 Paladin

* United States: 992
* Saudi Arabia: 177 ordered in April 2018.
* Republic of China (Taiwan) (**Cancelled**): >100 planned in 2019, 40 approved by U.S. State Department in August 2021. However, Taiwan’s Defense Ministry said they consider alternative options due to its uncertainty to be delivered, as U.S. DoD canceled the project.

#### M109A7

* United States: 48 with a further 180 contracted options

#### K55/K55A1

* South Korea: 1,040 K55 which is a license-production variant of the M109A2, and are upgrading entire inventory to K55A1. Operated by Army and Marine Corps.

### Former operators

#### M109A2/A3

* Belgium: 167 A2, of which 64 were upgraded to the -A4BE standard, the remainder being decommissioned
* Denmark: 2–6 (upgraded to M109 A3DK, used to be 76)
* Germany: 570 A3GE A1/A2, phased out by 1 July 2007 and replaced by the PzH 2000
* Italy: 221 M109L (with an Italian made 155 mm/39 calibre barrel) Replaced by PzH 2000
* Netherlands: 126 A2/90 phased out and largely replaced by the PzH 2000
* Norway: 33 in storage after donation of 22 to Ukraine in 2022. 55 in storage in 2021. Inventory of 14 M109A3GNM + 42 M109A3GN in 2019.
* Portugal: 6 A2 since 1981 (Portuguese Army). Currently retired from active-service and replaced by 18 M109A5 in 2002.
* United Kingdom: 140+ entered service in 1965, upgraded to -A1 and -A2 standards, and eventually sold to Austria in 1994
* Kuwait Unknown when got into service nor when it was withdrawn from service.

#### M109A4

* Belgium: 64 A4BE (all now decommissioned and some A3BE sold to Brazil and 36 A4BE to Indonesia)
* Canada: 76 A4B+ Phased out from the Canadian Forces since 2005, they were used between 1967 and 2005. All the vehicles had been modernized to the M109A4B+ SPH standard in the 1980s. They were primarily used by the 4 Canadian Mechanized Brigade Group in Germany.