The AMS (Armored Mortar System) was developed as a private venture by the Royal Ordnance and Delco Systems. It's development began in 1985. The AMS is intended to provide heavy mortar support for infantry units. The first prototype was built in 1986 and used M113 armored personnel carrier chassis. Improved AMS was ready for mass production in 1995. It used Swiss Piranha 8x8 APC chassis. The same armored personnel carrier was in service with the US Marines as the LAV-25. The AMS is in service with Saudi Arabian National Guard, which purchased 73 of these vehicles. This artillery system was trialed in Australia, however it received no production orders from this country

The AMS is a two-man turret, housing a 120-mm smoothbore breech loaded mortar. Vehicle provides direct and indirect fire support. The Armored Mortar System fires all standard 120-mm mortar mines, including HE-FRAG, smoke, cargo and illumination mines. Maximum range of fire is 6.5 km with ordinary mine and up to 12 km with rocket assisted. Intense rate of fire is 8 and sustained - 4 rounds per minute. The AMS can fire a 3 round burst in 15 seconds. Vehicle can engage armored targets with STRIX precision-guided projectiles. It has a range of 8 km and penetrates 700 mm armor plate.

Secondary armament consists of 12.7-mm or 7.62-mm machine gun, mounted on top of the roof. The Armored Mortar System is fitted with Delco GPS-aided fire control system.

Armor of the AMS provides protection against small arms fire and artillery shell splinters. Vehicle can leave firing position swiftly, once a fire mission has been completed.

Vehicle has a crew of four. It consists of driver, commander, loader and ammo preparer.

The AMS is powered by the Detroit Diesel 6V-53T diesel engine, developing 275 hp. Vehicle is fully amphibious. On water it is propelled by two waterjets.

AMS II, improved variant of the AMS developed by BAE Systems Land Systems. Maximum range of fire is around 10 km. It is compatible with SMART precision guided rounds. The AMS II incorporates new turret electrical system. It's fire control system enables fast and accurate targeting. It is claimed that the AMS II can fire the first round 15 seconds from vehicle stop. Maximum rate of fire is 13 rpm. Vehicle protection can be upgraded with add-on modular armor if required.