Designed for C-130 low-velocity air drop and roll-on/roll-off, the M8 Armored Gun System (AGS) can be flown with rapid deployment forces to troubled "hot spots" around the globe. The automatically loaded, lightweight 105mm cannon fires all NATO standard and enhanced ammunition at the rate of 12 rounds per minute. The quickness, balance and speed of the AGS provide superior mobility against battlefield opponents.

The AGS has increasing levels of modular passive protection that can be tailored to meet the tactical situation. Its built-in diagnostics locate and isolate trouble fast. Work on the vehicle's powerpack is an operator's dream. Layout of fire and operator's controls were designed for the crew. The commander has unsurpassed vision for first-look, first-kill capability. Backed by a world-class team, the AGS provides the potential capability to fulfill multiple missions and roles.

Following an international competition, in mid-1992 the US Army selected the FMC Corporation, Ground Systems Division (now United Defense LP), to build its Armored Gun System (AGS) to replace the M551 Sheridan light tanks used by the 3rd Battalion, 73rd Armor of the 82nd Airborne Division.

The M551 has now been retired from the US Army without replacement. A number of these vehicles are still however used in the training role, especially at the National Training Center. Details of the M551 were given in Jane's Armour and Artillery 1996-97 pages 174-175.

To reduce total life cycle costs, proven and in production subsystems have been used wherever possible, for example the engine is a derivative of that fitted to the M977 (8 x 8) truck, the transmission is from the Bradley, the commander's and gunner's hand controls are from the Bradley, the laser range-finder and crosswind sensor are from the M1A1 and the computer control panel is from the Challenger 2.

The XM8 was Type Classified as the M8 Armored Gun System in October 1995 by the US Army and declared production ready. However, on 5 February the US Army issued a Partial Stop Work notice to United Defense for the final phase of the EMD contract. This was followed by formal cancellation of the M8 AGS.

United Defense continues to market the M8 AGS overseas, especially Asia, the Middle East and Europe and one of the six prototypes of the vehicle was shown in Europe in June 1996.

Late in 1997, FNSS Defense Systems of Turkey and United Defense LP, teamed to offer the M8 AGS to the Turkish Land Forces Command (TLFC).

In September 1997, the second of the six prototype M8 AGS built with the highest protection Level III was demonstrated in Turkey during which it undertook firepower and mobility demonstrations for the TLFC.

According to United Defense LP, the M8 AGS is well suited to peacekeeping operations, such as Bosnia, where the TLFC has been deployed, as well as being used in traditional roles of reconnaissance.

As well as being less expensive to procure than an MBT, the M8 AGS has a much lower life cycle cost. According to United Defense, the fuel cost of the M8 AGS is US$0.60 per km compared to US$5.35 per km of a MBT with spare parts per km being US$35 and US$137 respectively.

The M8 is armed with a 105 mm M35 rifled gun, fed by an automatic loader, which fires the same natures of ammunition as all of the MBTs (Leopard 1, M48 and M60 series) currently in service with the TLFC.

If selected by Turkey, the M8 would be manufactured under licence by FNSS Defense Systems which is a joint venture company established to build 1,698 Armoured Infantry Fighting Vehicles.

The existing Turkish AIFV machinery, tooling and fixtures could be reconfigured for the M8 AGS with a minimum of investment according to United Defense.

The basic hull and turret of the M8 AGS is of all-welded aluminium armour construction which provides protection from small arms fire and shell splinters and to this is fitted a modular armour package.

The modular armour package permits the M8 AGS to be equipped with three increasing levels of external armour protection to meet different threats.

The level one package, which protects against small arms fire and artillery splinters, is designed for rapid deployment forces and gives a gross vehicle weight of 18,052 kg.

The level two armour package provides light forces with a higher level of protection and a gross combat weight of 20,820 kg.

Contingency forces expecting to face higher threats can equip the M8 AGS with level three armour package resulting in a gross weight of about 23,586 kg.

The heavier armour package will provide the M8 AGS with protection against threats up to and including hand-held anti-tank weapons.

The driver is seated at the front of the vehicle in the centre and has a single-piece hatch cover that lifts and then opens to the rear. This has five integral wide-angle periscopes for driving when closed down and, in addition, provisions are made for mounting a driver's passive night driving periscope.

Suspension is of the torsion bar type with six dual rubber-tyred roadwheels, idler at the front, drive sprocket at the rear and no track-return rollers. High-temperature shock-absorbers are provided at the first, second, third, fifth and sixth roadwheel positions. The suspension spring system provides a 250 mm jounce.

The front-mounted idler assembly is composed of standard M113A3 and M2 parts already in the US Army inventory. The track is of the steel double pin T150 type with detachable rubber pads, 152 mm pitch and 381 mm wide and has been developed by United Defense LP, Steel Products Division.

The M8 AGS is powered by a six-cylinder Detroit Diesel Model 6V-92TA developing 550 hp at 2,400 rpm on JP8 fuel and 580 hp on DF2 diesel fuel. This uses 65 per cent common components with the 8V-92TA engine installed in the Oshkosh Heavy Expanded Mobility Tactical Truck (HEMTT) M977 (8 x 8) already in service with the US Army in significant numbers.

The engine is coupled to a General Dynamics Defense Systems HMPT-500-3EC hydromechanical transmission, which is already installed in the M2 Bradley IFV, with a final drive ratio of 4.4:1.

The rear engine compartment roof is raised well above the turret ring so the 105 mm gun depression is limited to 0° over the rear arc. The air inlets/outlets are in the roof of the engine compartment with the exhaust at the left.

At the rear of the hull is a hydraulically actuated access ramp which, when horizontal, provides a work platform for ease of maintenance.

The engine, transmission and cooling system are mounted on rails and can be easily cranked out onto the ramp. Trained personnel can remove the complete power pack to the ramp platform where it can be ground hopped in less than 5 minutes. The M2 Bradley fan is belt-driven from a transmission-mounted PTO.

The turret is of all-welded aluminium with the automatic loader on the left and the commander and gunner on the right.

The gunner is seated forward of the commander and has a single-piece hatch cover that opens forwards. Forward of this is the Raytheon Systems Company two-axis stabilised day/thermal night sight with laser range-finder. Both commander and gunner have displays enabling either crew member to use the day or thermal channel. As a back-up, the gunner also has a fibre optic auxiliary sight mounted coaxially to the right of the main armament.

The commander is seated to the rear of the gunner and has a rotatable cupola with seven periscopes identical to the driver's for all-round observation (unity vision) and a single-piece hatch cover that opens to the rear.

The Raytheon Systems Company gunner's sight is based on a company-developed sight selected for the US Marine Corps LAV-105 assault gun which includes proven components from a number of Raytheon Systems Company products. The sight includes the Raytheon Systems Company HIRE, this is an Infra-Red Equipment (HIRE) which is a high-performance thermal imaging system consisting of three modular components, the sensor and gunner's display, commander's remote display and the power supply/ electronics. The sight also incorporates the laser range-finder from the M1 MBT and the line of sight stabilisation platform based on the South Korean K-1 MBT.

Turret and gun drives have been developed by HR Textron Incorporated and are based on those installed in the M1/M1A1/M1A2 MBT in service with the US Army. The gunner has twin control handles while the commander has a single control handle.

The 105 mm M35 gun is fully stabilised in both axes with an elevation of +20° and a depression of -10° through a frontal 270° arc. Turret traverse is a full 360°. Turret traverse and weapon elevation are hydraulic with manual controls for emergency use.

The Computing Devices Company of Canada digital fire-control computer is a modified version of that installed in the Challenger 2 MBT in service with Oman and the UK. Mounted on the turret roof at the rear is the wind sensor which feeds information to the fire-control computer.

Main armament comprises a 105 mm M35 rifled tank gun which includes a low-force gun mount. The six M8 AGS built so far have a pepperpot muzzle brake but these would probably not be fitted to production vehicles.

Mounted in the left side of the turret is an automatic loader which enables a rate of fire of 12 rds/min to be achieved.

Once the target has been designated, the gunner selects either automatic (for multiple shots) or single-shot modes as well as the type of round desired. The ammunition is automatically loaded at the rate of one round every 5 seconds and the system can be operated on the move. A back-up design feature allows manual loading of the main gun from under armour should it become necessary.

The automatic loader holds 21 rounds of 105 mm ammunition stowed vertically base downward. A chain drive moves the rounds along a crescent-shaped pathway to the loading position. A loading arm with a ram tray assembly then takes the round and inserts it in the breech of the gun in one upward and forward movement.

Once the gun has fired, it recoils 533 mm to the rear and returns to battery. The 105 mm gun returns to 0° for case ejection and reloading. The breech is hydraulically opened and the empty case is ejected through the loading port in the turret bustle. When the gun is depressed below 7°, a linkage-operated gun cover in the roof lifts to clear the recoiling breech.

The automatic loader is separated from the crew compartment by a bulkhead containing an access panel for manual loading. Blow-out panels are provided in the turret roof.

The 105 mm M35 gun fires all standard US NATO tank ammunition including APFSDS-T, APERS, WP, HEAT and HESH and their respective training rounds.

A standard 7.62 mm M240 machine gun is mounted coaxially to the right of the main armament, provided with 1,000 rounds of ready use ammunition and a further 3,500 rounds of ammunition carried in reserve in the turret.

A number of weapons can be mounted externally on the commander's cupola including a 12.7 mm M2 machine gun, 7.62 mm machine gun or a 40 mm Mk 19 grenade launcher.

Mounted either side of the turret is a bank of eight electrically operated grenade launchers which can fire a wide variety of grenades over the frontal arc and a missile countermeasure package can be fitted to the M8.

The M8 AGS is fully transportable in a C-130 transport aircraft. With the level I armour package it can be air-dropped, with the level II armour package it can be driven on and off a G-130, while with the heaviest level III armour package it is air-transportable in a C-17 transport. The C-17 can carry three M8s while the C-5 can carry five vehicles.

Development complete. Type Classified by US Army as M8 Armored Gun System but not funded for production.