It is created in 1978.

It is installed on:

• AMX-30

• T-72

• ARJUN

• LEOPARD

The 155 mm GCT (Grande Cadence de Tir) was developed by the now Nexter Systems (previously Giat Industries) from 1969 to meet a French Army requirement for a self-propelled gun to replace the 105 mm and 155 mm self-propelled weapons, both based on the chassis of the AMX-13 light tank, then in service.

The first prototype was completed in 1972 and was shown for the first time at the 1973 Satory Exhibition of Military Equipment.

Between 1974 and 1975 six preproduction vehicles were completed and the vehicle entered production in 1977. First production GCTs were delivered in 1978 to Saudi Arabia.

The 155 mm GCT self-propelled howitzer was officially selected by the French Army in July 1979.

The French Army designation for the GCT is the 155 AUF1 of which 179 are in service. From 1988, production switched to the improved 155 AUF1 T with a total of 94 (74 plus 20) delivered to the French Army. This has a number of improvements including a more powerful APU, an improved and more reliable automatic ammunition loading system and an inertial goniometer.

Production of the 155 mm GCT self-propelled gun for the French Army commenced again in 1995 with first production systems being completed in 1996. This batch consisted of 20 vehicles.

The GCT has seen action with the French Army in Bosnia. It has also seen extensive service with the Iraqi Army in its war with Iran.

Although production of the Nexter 155 mm GCT is now complete, marketing of the complete GCT self-propelled artillery system continues. In addition, the GCT turret has been marketed for many years as a stand-alone system for integration on other tank chassis.

As of early 2008, there had been no sales of the GCT turret system for installation on other chassis. Of the 273 systems built for the French Army a total of 104 have now upgraded to the enhanced AUF1-TA standard, details of which are given later on in this entry.

The 155 mm GCT basically consists of a modified AMX-30 MBT chassis fitted with a new turret armed with a 155 mm gun and an automatic loading system. The vehicle has a crew of four that consists of the commander, gunner, loader and driver.

The hull is almost identical to that of the AMX-30 MBT apart from the following modifications which result in the chassis being 2,000 kg lighter than the MBT's: the 155 mm ammunition racks in the hull have been removed, and a 5kVA 28 V generator and a ventilator system to supply the turret with cold air have been installed.

The driver is seated at the front of the vehicle on the left side and has a single-piece hatch cover that opens to the left, in front of which are three day periscopes. The centre day periscope can be replaced by an image intensification periscope for night driving or a combined SOPELEM OB-16A day/night periscope.

The turret is in the centre of the vehicle. The power pack is immediately behind the bulkhead that separates the engine compartment from the turret compartment. The transmission consists of an automatic clutch, a combined gearbox and steering unit, brakes and two final drives. The centrifugal-type clutch is activated electrically by a gearshift lever. The combined gearbox and steering mechanism contains a mechanically operated gearbox giving five speeds both forward and reverse, and a triple-differential steering system. The brakes are hydraulically operated and are used both as service and parking brakes. Each final drive comprises a spur-type right angle and an epicyclic gear train.

The torsion bar suspension either side consists of five, dual, rubber-tyred road wheels with the idler at the front, drive sprocket at the rear and five track-return rollers that support the inside of the track only. The first, second, fourth and fifth road wheels are mounted on bogies and the first and last road wheel stations have a hydraulic shock-absorber.

The turret is all-welded steel with the commander and gunner seated on the right and the loader on the left. The commander's cupola is equipped with day periscopes for all-round observation and has a single-piece hatch cover that opens to the rear. The loader, who also operates the roof-mounted 7.62 mm or .50 (12.7 mm) M2 HB anti-aircraft machine gun, has a single-piece rear-opening hatch cover. The crew enters the turret via a door in each side.

The 155 mm 40 calibre barrel has a vertical sliding wedge breech block hermetically gas-sealed by a metal blanking plate. The breech is hydraulically opened with manual controls for emergency use. The barrel has a double-baffle muzzle brake. The 155 mm gun has an elevation of +66°, depression of -4° and the turret can be traversed through 360°. Turret traverse and gun elevation are hydraulic with manual controls for emergency use.

The weapon takes 1 to 2 minutes to bring into action and 1 minute to bring out of action. Average rate of fire is 8 rds/min with automatic loading and 2 to 3 rds/min with manual loading. For burst fire, six rounds can be fired in 45 seconds.

Forty-two projectiles and 42 cartridge cases are carried in the turret rear arranged in seven racks of six identical shells and seven racks of six cartridge cases; in addition, 22 propelling charges for short range are housed near and under the loader's seat. A typical ammunition load would consist of 36 (6 × 6) HE shells plus six smoke (1 × 6) or 30 HE (5 × 6), six smoke (1 × 6) and six illuminating (1 × 6); but any combination of HE, illuminating or smoke shells is possible in racks of six similar shells. The various types of shell can be selected and fired with automatic loading without any preparation of the loading system.

The gunner can select single shots or bursts of six rounds. The turret is re-supplied with 155 mm ammunition by two large doors in the turret rear which fold down into the horizontal to provide a platform for the crew. The turret can be reloaded by a crew of four in 15 minutes or by a crew of two in 20 minutes. The gun can continue to fire while being reloaded.

The 155 mm gun can fire the following types of separate loading (for example projectile and charge system) 155 mm ammunition:

• 155 mm HE 56/69 with a maximum range of 23,000 m

• 155 mm HE (hollow base) with a maximum range of 23,000 m

• 155 mm HE (base bleed) with a maximum range of 29,000 m

• 155 mm HE US M107 with a maximum range of 18,000 m.

Other types of projectiles including illuminating, smoke and carrier can be fired.

It will also fire the BONUS top-attack anti-tank munition developed jointly by Nexter Munitions of France and the now BAE Systems Bofors of Sweden. First production Bonus projectiles were delivered in mid-2002. It is now operational in France and Sweden but as of early 2008 there are no exports.

The fire-control system of the standard production GCT consists of the following:

• Gimbal suspension providing for the mounting of the goniometer in the turret and permitting it to move freely by 10° relative to the axis in all directions

• One hermetically sealed conventional optical goniometer. Traverse angles are read on engraved drums and elevation angles appear on an elevation scale

• One azimuth plate that can be manually adjusted and is provided with a spirit level to set the goniometer vertically

• A contrarotation device making it possible to preserve the vertical position of the goniometer during turret rotation

• A direct fire sight for anti-tank firing.

A 7.62 mm or a .50 (12.7 mm) M2 HB machine gun can be mounted at the loader's station for anti-aircraft defence. The 7.62 mm machine gun has an elevation of +45°, a depression of -20°, total traverse of 360° and is provided with 2,050 rounds of ammunition, of which 550 rounds are for ready use. The .50 (12.7 mm) M2 HB machine gun has an elevation of +50°, a depression of -20°, total traverse of 360° and is provided with 800 rounds of ammunition of which 100 are for ready use. Two electrically operated smoke grenade dischargers are mounted on the forward part of the turret, below the main armament.

The standard optical control system can be replaced by a CITA 20 system which consists of a land navigator coupled with a gyroscope. When the 155 mm GCT comes to a halt the crew knows immediately the co-ordinates of its position and the bearing of its ordnance.

During a defence equipment exhibition held at Le Bourget in mid-1992, the company showed a Russian T-72 MBT chassis fitted with the complete turret of the GCT self-propelled artillery system. This was aimed at the Indian market which has a requirement for a 155 mm system on a T-72M1 MBT chassis has been manufactured in India. This system was demonstrated in India together with the South African Denel Land Systems T6, the Slovak Republic Zuzana and the now BAE Systems Land Systems UK AS90 turret, all of which were installed on a locally supplied T-72M1 MBT chassis.

In September 1999 the Delegation Generale pour l'Armement (DGA) awarded the then Giat Industries a FFr325 million development contract for the AUF1/AUF2 programme for the French Army.

This covered the upgrade of the first batch of 10 systems that retain the current 155 mm/40 calibre barrel. It also included: installation of the Thales Communications ATLAS FCS; fitting of muzzle velocity radar over 155 mm ordnance; refurbished and upgraded turret and chassis.

The existing power has been replaced by a more fuel efficient and reliable Mack E9 diesel coupled to an ENC 200 transmission.

It was expected that the French Army would have upgraded a total of 174 155 mm AUF 1 weapons, of which 70 would have been fitted with a 155 mm/52 calibre ordnance plus all of the other systems. This would have been designated the AUF 2.

The remaining 104 would have retained the 155 mm/40 calibre barrel plus all of the other systems. These will be designated the AUF1-TA.

The enhanced turrets are mounted on an upgraded AMX-30B2 type chassis fitted with a Renault/Mack E9 engine. This engine, with the associated semi-automatic SESM ENC 200 gearbox proves the system with a much-improved power-to-weight ratio.

According to the company, this is greater than the original configuration by 20 per cent. This gives the system mobility and manoeuvrability identical to those of MBTs.

The AUF1-TA turret retains the original ordnance, fully automated loading of the projectiles and charges, hydraulic aiming system and the CITA 20 SAGEM onboard navigation system.

The enhanced 155 mm/52 calibre version provides for the integration of the following new subsystems:

• Ballistic CALP 2G computer from EADS

• Installation of a RDB4 muzzle velocity radar from IN-SNEC

• PRISM electronic fuze programming device from TDA

• Two PR4G type frequency-hopping radio sets

The first qualification example was delivered by the company to the French DGA late in 2002, who then commenced qualification tests.

Late in 2003 it was revealed that the French Army had changed its policy on the upgrade of the GCT, and the 155 mm/52 calibre version will not be procured in the short term at least.

The French Army has decided to procure an initial batch of 72 CAESAR 155 mm/52 6 × 6 self-propelled artillery systems based on a new Renault Trucks Defense Sherpa (6 × 6) chassis.

Final deliveries to the French Army were made in 2007.

Each AUF1 regiment has four batteries, each with eight weapons that can be split into two troops with four weapons.

In addition to the installation of the 155 mm/52 calibre ordnance, the AUF2 upgrade would also have included the installation of a new cradle, a new screw-type breech mechanism, new double baffle muzzle brake and modified recoil system.

ATLAS reduces the engagement cycle as well as increasing accuracy and enables Multiple-Round Simultaneous Impact (MRSI) missions to be accomplished. Part of the fleet will also have a muzzle velocity radar which will feed information to the onboard fire-control system.

The installation of an automatic loading system relays the ordnance after each round has been fired and also gives the upgraded GCT a Multiple Rounds Simultaneous Impact (MRSI) capability.

To come into action, fire a 10 round salvo and come out of action, takes 2 minutes. It is also fitted with a chamber monitoring device and an automatic feeding system for the primers.

Range depends on projectile and charge combination, but the BONUS top attack anti-tank projectile can be fired to a maximum range of 35 km, the LU 211 base bleed high-explosive shell to a maximum range of 39 km and firing an extended range, full-bore projectile, a range of 42 km can be achieved.

In addition, the AUF2 would have had its automatic loading system adapted to NATO standard modular propellant charges. The now Nexter and SNPE developed the new modular charge system under contract to the DGA, with a maximum of six modules being used with a 155 mm/52 calibre barrel and five modules with a 155 mm/40 calibre barrel. The modular charge consists of two modules, Top Charge System (TCS) and Bottom Charge System (BCS).

The TCM weighs 2.6 kg and uses multibase propellant, while the BCS weighs 2 kg and uses single-base propellant. Both use a black powder ignition system. Maximum muzzle velocity is quoted as 945 m/s.

Development of the new French modular charge system is complete and an industrialisation contract has now been awarded. A typical upgraded GCT will carry 180 TCSs and 20 BCSs.

A total of 42 155 mm projectiles of various types plus modular charges are carried in the turret rear with a maximum stated rate of fire of 10 rds/min.

The AUF is based on a modified AMX-30 Main Battle Tank (MBT) chassis that was manufactured by the then Giat Industries at their Roanne facility. This was upgraded at a French Army depot prior to being supplied back to the company where it will be integrated with the refurbished and upgraded turret.

Air defence consists of the roof-mounted .50 (12.7 mm) M2 HB machine gun with the option of the GALIX armoured vehicle protection system. Add-on armour is also possible and a collective NBC system is fitted as standard.

In mid-2004 the then Giat Industries facility at Bourges completed the first upgraded 155 mm AUF1 self-propelled gun (SPG) for the French Army under the designation of the AUF1-TA. By the end of 2004 a total of 18 units were delivered, with 33 following in 2005, 33 in 2006 and the remaining 10 in 2007.