FH - 70 The FH - 70 ( field howitzer for the 1970s ) is a towed howitzer in use with several nations . History . In 1963 NATO agreed a NATO Basic Military Requirement 39 for close support artillery , either towed or tracked . Subsequently Germany and UK started discussions and design studies and in 1968 established agreed operational characteristics for a towed 155 mm close support gun . Italy became a party to the agreement in 1970 . Key requirements were a detachable auxiliary power unit ( APU ) , an unassisted range of 24 km , 30 km assisted , a burst capability of 3 rounds in 15 – 20 seconds , 6 rounds per minute for a short period and 2 rounds per minute sustained . The gun was to fire all 155 mm munitions in NATO service and have a new range of ammunition . The two national authorities had overall responsibility for R & D , and Vickers Ltd was the co - ordinating design authority . They were also the design authority for the carriage and Rheinmetall GmbH was the authority for the elevating mass , including the sights , and for the APU . There was a further breakdown at a more detailed level and production worksharing . The UK Royal Armament Research and Development Establishment ( RARDE ) was responsible for designing the HE projectile and the charge system . Germany was responsible for Smoke , Illuminating , Minelet and extended range HE , although development of the last two was not completed in the program . The intention was for FH70 to replace the M114 155 mm howitzer and equip general support battalions in German divisional artillery regiments and to equip three ( two Territorial Army ( TA ) ) British general support medium regiments replacing the 5 . 5 - inch gun . In the event , it actually equipped UK regular regiments in direct support of infantry brigades until after the end of the Cold War , and only replaced the L118 light gun in two TA regiments , 100th ( Yeomanry ) Regiment Royal Artillery and 101st ( Northumbrian ) Regiment Royal Artillery ( Volunteers ) from 1992 to 1999 . Design . FH 70 had several interesting features , including : The barrel was 39 calibre s long , giving 827 m / s standard maximum MV . It had a muzzle brake giving 32 % efficiency . Other conventional features included a split trail and turntable sole plate . Initially , it had assisted loading , but became an early user of flick - ramming . In accordance with long - standing UK practice , it used one - man laying . All this meant that the gun could be operated by a minimum detachment of only 4 men ( commander , layer and 2 loaders ) . The burst fire rate was 3 rounds in 15 seconds . It was also fitted with a direct fire telescope . There were a number of design flaws that became apparent in service . The equipment entered full operational service in the UK in 1980 , and it became clear that there were significant difficulties with the tube feed system in anything but ideal conditions . 1st Regiment RHA , a unit tha had conducted the Troop trials , evolved their own procedures to cure the problems , which related to dust contamination , and this process became established in official manuals in due course . More significantly , the trails of the gun proved to be weak at the point where maximum stresses incurred when the equipment was towed ; this resulted in modification work on the UK guns in 1987 . There were continual problems with the drive train on the flat - 4 VW APU , and the hydraulic system was always vulnerable to the obvious problems posed by external , non - armoured hosing , in combat conditions . In addition , the complex dial sight carrier was vulnerable to damage . Ammunition . The new projectiles conformed to the Quadrilateral Ballistics Agreement between US , UK , Germany and Italy . In essence , this meant a shell with the same shape and dimensions as the US M549 rocket - assisted projectile . The standard HE shell ( UK designation L15 ) is a thin wall design weighing 43 . 5 kg and containing 11 . 3 kg of HE . This remains the largest HE load for a standard 155mm shell . The propellant system comprises 3 different bagged cartridges with triple - base propellant . Cartridge 1 gives charges 1 & 2 , Cartridge 2 give charges 3 – 7 and Cartridge 3 is charge 8 , which gives a maximum range under standard conditions of 24 . 7 km . Each nation developed its own fuses and ammunition packaging . In the UK ' s case , this led to the Unit Load Container carrying 17 complete rounds , including shells with fuzes fitted - a novelty for 155 mm . Standard US pattern 155 mm ammunition can also be fired , although US primers proved problematic for the primer magazine and feed due to their variation in size . References . RB Pengelley " FH 70 - Europe ' s first multi - national artillery program " International Defense Review Vol 6 , No 2 April 1973