AS - 90 The AS - 90 ( acronym for : " Artillery System for the 1990s " , known officially as : " Gun Equipment 155 mm L131 " ) is a lightly armoured self - propelled artillery piece used by the British Army . The AS - 90 was first deployed by the British Army in 1993 . 179 were acquired to re - equip six of the eight self - propelled field artillery regiments ( each 24 guns ) in the 1 ( BR ) Corps , replacing the 105 mm FV433 Abbot SPG and older M109 155 mm Self Propelled Gun . It remains in UK service and will equip three field regiments supporting armoured infantry brigades for the foreseeable future . AS - 90 was designed and built by the Armaments division of Vickers Shipbuilding and Engineering ( VSEL ) , whose parent company became BAE Systems in 1999 . VSEL provided 179 vehicles between 1992 and 1995 at a cost of £ 300 million ( $ 480 million USD ) . The AS - 90 underwent a capability enhancement program in 2008 and 2009 , primarily relating to upgrades of the AS - 90 ' s electronic system . In 1999 , Marconi Electronic Systems was contracted to upgrade British Army AS - 90s to include a 52 calibre gun in order to increase the range of the artillery . Critical to the program was a bi - modular charge system from Somchem of South Africa ( selected after extensive trials of ammunition from many suppliers ) , which offered greatly reduced barrel wear . However , this ammunition failed to meet the requirement for insensitive munitions and the project was terminated . Development . AS - 90 started in the mid - 1980s as a private venture on the ' gamble ' that the tri - national SP70 would fail . When this duly occurred , the Ministry of Defence ( MoD ) issued a cardinal point specification on one page for a new 155 mm SPG . Four tenders were submitted , and AS - 90 was the only offer that was not ' brochureware ' . The MoD was also required to consider the US " Paladin " , an upgraded M109 howitzer . The MoD has undertaken studies in 2006 - 09 to " up gun " the Royal Navy ' s main shipboard gun armament , the 4 . 5 inch Mark 8 naval gun , to accept the 155 mm ordnance from the AS - 90 . This would introduce a common gun calibre for the British Army and Royal Navy , helping with ammunition logistics , and encouraging joint Army - Navy development of extended range and precision guided shells . Design . In 1963 certain NATO nations , including the UK , agreed a Ballistics Memorandum of Understanding for a 155 mm 39 calibre ordnance and a baseline projectile with the shape used for the US M549 rocket - assisted shell . The AS - 90 uses a conforming 39 calibre barrel which fires the L15 unassisted projectile out to a range of 24 . 7 km . However , this was a new design of ordnance and uses a split sliding block breech with Crossley obturation , instead of the more usual screw breech , to permit bagged charges ( no metal cartridge cases ) . The breech mechanism has a primer magazine holding 18 primers . It is fitted with an auxiliary power unit to eliminate the need to run the main engine to keep the batteries charged while stationary ; electrical servos drive the automated elevation , traverse , magazine , shell transfer arm and loader as well as power for electronics and communications . The vehicle is fitted with an autonomous navigation and gun laying dynamic reference unit ( DRU ) mounted on the trunnion . All main turret functions are controlled by a Turret Control Computer ( TCC ) with control and display units for the No 1 ( Detachment Commander ) , No 2 ( loader ) and No 3 ( layer ) . The combination of the DRU , TCC and powered laying controls provide autolaying . Every gun is fitted with a radar Muzzle Velocity Measuring Device . Reversionary mode laying uses deflection laying via the direct fire sight . The gun can be brought into action fully closed down , the barrel can be clamped and unclamped from within the vehicle . Into and out of action times are less than 1 minute . Variants . AS - 90D - Modified for desert use . Thermal protection for crew and extra cooling for engine and machinery . Tracks adapted for reduced wear in sandy conditions . AS - 90 " Braveheart " - Basically the AS - 90 , but fitted with the 52 calibre length gun . This project was terminated due to non - compliant propellant charges . Haubicoarmata " Krab " - ( eng . " Howitzer - cannon Crab " ) Licensed " Braveheart " turret on a Polish chassis UPG , with modern " Azalia " BMS . Designed and integrated in Poland , by Huta Stalowa Wola and WB Electronics . , two Krab ( " Crab " ) prototypes were built , and successfully completed all required evaluations and state acceptance trials . Initial serial production started in 2008 , 24 units are planned before 2015 of 72 projected for Polish Land Forces with 8 in testing phase as of 2012 .