Description

The 155mm M198 is the premier weapon of the Royal Australian Regiment of Artillery. It is an indirect fire gun, employed in groups to generate firepower over great distances. It can be transported by a Chinook helicopter or C130 Hercules. It fires rounds up to 24km which can be selected to explode on impact or a variety of other effects as required. It is usually towed behind a truck a delivered to its postion before being readied for firing.

The M198 weapon is mounted on a split trail carriage, fitted with a two-position rigid suspension system which can be rotated upwards to raise the wheels. This allows the weapon to rest on a non-anchored firing platform. When travelling the ordnance remains forward, but for storage it can be traversed through 180º and locked in position over the closed trails.

The carriage consists of the top carriage, elevating mechanism, equilibrators, traversing mechanism, bottom carriage, wheel suspension assembly, speed shift, trails and firing base.

The recoil mechanism is of the hydropneumatic type with a variable recoil length. The autofrettaged ordnance has a screw-on double-baffle muzzle brake, and a screw breech mechanism with a conventional obturator pad and split ring seal obturator.
The fire-control equipment includes an M137 panoramic telescope with a magnification of ×4 and a 10º field of view, two elevation quadrants (M17 and M18) and an M138 elbow telescope with a magnification of ×8 and a 6º field of view.
The internal configuration of the Cannon Assembly M199 is in accordance with the German/British/American/Italian quadrilateral agreement and will fire all current standard and developmental 155 m ammunition of the anti-material and anti-personnel types. The weapon can fire the following types of 155 mm ammunition:

• Anti-tank (M718 & M741) FASCAM AT Round containing nine anti-tank mines with the projectile weighing 46.72 kg, a muzzle velocity of 660 m/s and a maximum range of 17,740 m
• Copperhead Cannon Launch Guided Projectile (M712) a laser guided HE round guided by ground designation. effective to a range of 16,400 m
• HE (M107) Basic HE round used in AS 155mm equipment with the projectile weighing 42.91 kg, muzzle velocity of 684.3 m/s and maximum range of 18,100 m
• HE (M449) APERS Cluster munition containing 60 anti-personnel grenades. the projectile weighs 43.09 kg and a maximum range of 18,100 m
• HE (M483) FASCAM DP round containing 88 dual-purpose grenades. the projectile weighs 46.53 kg, muzzle velocity of 660 m/s and a maximum range of 17,500 m
• HE (M692 & M731) FASCAM APERS round containing 36 anti-personnel mines. the projectile weighs 46.5 kg, muzzle velocity of 660 m/s and a maximum range of 17,740 m
• HE (M795) registration projectile for M483 and maximum range of 22,400 m
• HERA (M549 series) HE round with a rocket assist projectile, weighing 43.54 kg, maximum muzzle velocity of 826 m/s and a maximum range of 30,000 m
• DPICM (Dual-Purpose Improved Conventional Munition) M864 (type-classified late in 1987)
• Illuminating (M118 series) Magnesium-based Illumination round with the projectile weighing 46.26 kg, muzzle velocity of 684.3 m/s and a maximum range of 18,100 m
• Illuminating (M485 series) Magnesium-based Illumination round with the projectile weighing 41.73 kg, muzzle velocity of 684 m/s and a maximum range of 17,500 m
• Smoke WP (M110 series) White Phosphorous marking round with the projectile weighing 44.4 kg, muzzle velocity of 684.3 m/s and a maximum range of 18,100 m
• Smoke BE (M116 series) 3-canister base-eject smoke round of various colours with the projectile weighing 42.22 kg, muzzle velocity of 684.3 m/s and a maximum range of 18,100 m
• Smoke BE (M825) 3-canister base-eject smoke round of various colours with a muzzle velocity of 797 m/s and a maximum range of 22,600 m.

It will also fire the latest 155 mm natures of ammunition such as the SADARM (Sense And Destroy Armour) and the future XM982 Extended Range Projectile now under development by Raytheon Systems. This is not expected to enter service for some years as it is still at the Engineering Manufacturing and Development (EMD) phase.