In June 2009, Chile’s formal request to buy a variety of artillery-related systems and equip a new mechanized artillery battalion was cleared by the US state Department, and allowed to go forward. The request centered on BAE’s M109 tracked self-propelled howitzer, but it also includes necessities like shells, tracking radars, and accompanying personnel carriers. Chile already operates the M109 self-propelled howitzer, and this order could double its available fleet, to a total of 48.
Chile’s current stock of 24 M109s are the KAWEST version, which were upgraded by Switzerland’s RUAG external link and sold to Chile at the end of 2004. The Swiss upgrades included an L47 gun with 27 km/ 36 km assisted range and 3-round burst capability over 15 seconds, 6 crew members instead of 8, carriage of 40 rounds and 64 charges, improved electrical systems, an integrated inertial navigation and positioning system, day and night capability, and added protection against fire, nuclear EMP (Electro-Magnetic Pulse radiation), and NBC (Nuclear, Biological, Chemical) threats.
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.
The M109A3s are M109A1s that were rebuilt with 27 mid-life improvements to reliability, availability, and maintainability (RAM). The most significant additions were the long barreled 155 mm M185 cannon, ballistic protection for the panoramic telescope, and the ability to store 36 rounds of 155mm ammunition, instead of just 28. The M109A5s add a number of newer features over the M109A3, including a new M285 155/30mm cannon in a new mount.
All of these M109 variants retain the need to physically string communications wires between the howitzers and the fire-control center, as part of a 15-20 minute emplacement procedure. Full “move, fire, move” capability is restricted to the M109A6 Paladin variant, fielded by the US Army.