M109

M109A5

M109A5: M284 L/39 155mm howitzer

The M109 was a 155mm self-propelled howitzer introduced in 1963 to replace the M44. It was used by the Imperial Army during the Third Great War.

## Variants

**M109:** Original version introduced in 1963. It had a 23-calibre 155mm M126 gun in an M127 Howitzer Mount, and carried 28 rounds of 155 mm ammunition. It was also armed with a 12.7mm 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:** Introduced in 1973. Replaced the M126 gun with a longer barreled, 39-calibre M185 gun, increasing maximum range to 18,100 meters.

**M109A2:** Introduced in 1978. Incorporated 27 Reliability, Availability, and Maintainability (RAM) mid-life improvements. Most notably, the long-barreled 155mm M185 cannon in the new M178 gun mount, ballistic protection for the panoramic telescope, counterbalanced travel lock, and the ability to mount the M140 alignment device. Stowage of 155mm rounds increased from 28 to 36 rounds; 12.7mm ammunition remained at 500 rounds.

**M109A3:** M109A1s rebuilt to M109A2 standard.

**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) 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 A4 also adds 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:** Introduced in 1985. Replaced 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 Projectiles (RAP Rounds). The vehicle can carry 36 complete rounds of ammunition and has a 328 kW engine instead of the standard 302 kW engine.

**M992 FAASV:** Ammunition resupply vehicle based on M109 chassis, introduced in 1982. It replaced the M548 supply vehicle. 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. There is a maximum of 90 conventional rounds, 45 each in two racks, and 3 M712 Copperhead rounds. Much of the remaining internal crew space is taken up by a hydraulically powered conveyor system designed to allow the quick uploading of rounds or transfer of rounds to the M109-series howitzer. Most early models had an additional mechanism called an X-Y Conveyor to lift the rounds into the honeycomb-like storage racks in the front of the superstructure. A ceiling plate above the two racks can be unbolted and opened to allow the racks to be winched out of the vehicle. 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.