The 120mm Armoured Mortar System - AMS II has been developed as a private venture by BAE Systems, RO Defence and General Dynamics Land Systems - California Technical Center, to meet emerging operational requirements for an advanced mortar system capable of providing highly effective indirect offensive fire support with the added benefit of direct fire against selected targets.

The first generation AMS is already in service with the Saudi Arabian National Guard (SANG) on a General Dynamics Land Systems - Canada Light Armoured Vehicle (LAV) (8 × 8) chassis.

A total of 73 AMS have been supplied as part of a Foreign Military Sales (FMS) deal covering the supply of 1,117 vehicles. Details of the first generation AMS are given in a separate entry.

Within the AMS II team, BAE Systems, RO Defence is responsible for the turret structure and 120 mm smoothbore breech-loaded mortar, while General Dynamics Land Systems - California Technical Center is responsible for fire-control system and electronic systems. Turret integration is a joint responsibility.

In appearance the latest AMS II is very similar to the first generation AMS but the new AMS II has a number of significant improvements.

The improved design turret shell is of all-welded steel armour, which provides the occupants with protection from small arms fire up to 7.62 mm armour-piercing (AP) short form, as well as shell splinters.

The third member of any programme would be the chassis supplier. AMS II was shown for the first time late in 2003 installed on the Swiss MOWAG Piranha III (8 × 8) chassis. It has also been fitted onto an Alvis Vickers Warrior infantry fighting vehicle chassis and a German Waran chassis.

The earlier AMS has already been successfully tested on the United Defense Mobile Tactical Vehicle Light (MTVL) full tracked chassis.

The baseline AMS II turret system weighs less than 2,500 kg, which makes it suitable for installation on a very wide range of tracked and wheeled chassis including Warrior, Waran, Waran II, Puma, Piranha IV and the Patria Vehicles Armoured Modular Vehicle.

A number of appliqué armour packages will be offered to provide turret protection levels equal to that of the chassis on which the turret is installed. One of these would take protection levels to defeat 14.5 mm armour piercing attack. Spall liners can also be fitted.

The first generation AMS had electro-hydraulic drives and a first generation fire-control system. AMS II has a new all-electric system and a computerised day/night fire-control system, a much higher level of situation awareness and open systems architecture to interface with future networked battle management systems.

The integrated direct-fire day/night sight has ×8 standard day optics with integrated laser range-finder. It is also fitted with a position/pointing inertial reference system, which is GPS aided. The fire-control computer can accept direct inputs from the commander or via digital communications message.

According to the consortium, AMS II takes 15 seconds to come into action and less than five seconds to come out of action with a cyclic rate of fire of 13 rounds per minute. Maximum indirect fire range is from 500 to 10,000 m while direct fire range is from 250 to 1,200 m.

The breech-loaded 120 mm smoothbore mortar will fire all standard natures of 120 mm smoothbore mortar ammunition including the M530 high explosive, smoke and illumination bombs while submunition and the Swedish Strix precision guided munition have also been fired.

When installed on an LAV-III chassis, for example, one system could be carried internally of a C-130 Hercules while the future A400M could carry two.

A Piranha/LAV-III would carry about 65 120 mm mortar bombs, all of which would be stowed below the turret ring.

Radios and intercom would be to customer specifications, as would an NBC system. A 12.7 mm or 7.62 mm machine gun can be pintle-mounted on the turret roof for local and air defence purposes and banks of electrically-operated smoke grenade launchers are mounted either side of the turret, firing forwards.

The consortium is already looking at further enhancements to AMS II for other applications such as the US Army's Future Combat System Non Line Of Sight - Mortar (NLOS-M), for which AMS is one of the two contenders, and the UK's Future Rapid Effects System (FRES). These could include a load-assist device and sensor-to-shooter fire control.