BL 5 . 5 - inch Medium Gun The BL 5 . 5 inch Gun was a British artillery gun introduced during the middle of the Second World War to equip medium batteries . History . In January 1939 a specification was issued for a gun to replace the 6 inch 26 cwt howitzer s in use with most medium batteries . The first units were equipped in UK in the summer of 1941 and in North Africa a year later , 20 guns equipped British and Free French batteries at El Alamein . Subsequently it also equipped Canadian , Australian , South African , Polish and Indian regiments , and after the war , it was also used by New Zealand . In the Second World War the normal organisation was a regiment of 16 guns organised into two batteries . The 5 . 5 was retained in service after the war . It was used by the Royal Artillery on operations in Korea , South Arabia and Borneo . It was ( probably ) used by the Indian Army in wars against Pakistan . The South African Defence Force used it extensively in the early stages of the South African Border War , including Operation Savannah , calling it the G2 . In British post - war service it also replaced the BL 4 . 5 inch Medium Field Gun When 6 gun batteries were introduced in the late 1950s , medium regiments had 18 guns and the third battery in each field regiment was equipped with 5 . 5 inch guns instead of 25 pounder guns . It remained in UK service with Territorial Army regiments until 1980 and in Australian service until replaced by M198 in about 1984 . The UK replacement for 5 . 5 inch was the FH - 70 155 mm towed howitzer , in service as L121 . The last 5 . 5 rounds were fired in the UK in 1995 . In use , the 5 . 5 was generally towed by the AEC Matador artillery tractor . From the 1950s in British service , the 5 . 5 was typically towed by an AEC Militant Mk 1 6x6 truck and subsequently the FV 1103 6x6 Medium Artillery Tractor built by Leyland . All 5 . 5 guns were manufactured in the UK . Description . There were four marks of 5 . 5 inch ordnance although only 3 and , after World War II , 4 entered service , and the differences were only minor . There were two marks of carriage where the differences were greater use of welding and less of riveting . The carriages were identical to those used with Ordnance BL 4 . 5 inch Mark 2 . No limber was ever used and the gun fired with its wheels in contact with the ground . During World War II the PL Locks and AC Slide Boxes used with 0 . 5 inch tubes were replaced by PK Locks and Y Slide Boxes using 0 . 303 inch tubes . It used one man laying and had Probert pattern calibrating sights . The Dial Sight was initially the No 7 but was gradually replaced by the No 9 . In the 1960s sights were converted from degrees , minutes and yards to mils and metres . There was no anti - tank telescope . Late in the war a sight adapter was introduced to permit upper register ( high angle ) fire when the wheels were raised significantly above the level of the spades . The normal gun detachment was 10 men . Ammunition . Initially 5 . 5 inch fired a 100 lb shell ( 6 / 12 crh ) and 4 charges in two cartridges giving a maximum range table MV of 1675 feet per second and 16 , 200 yards . In 1944 an 82 lb shell ( 8 / 16 crh ) was introduced along with Charge Super giving a maximum range table MV of 1950 feet per second and 18 , 100 yards . The lighter shell contained 1 . 5 lbs more HE and gradually replaced the heavier shell . In addition to HE there were several chemical ( 90 – 98 lbs ) and coloured smoke shells ( 100 lb only ) , coloured flare was developed . After the war only HE was used . The normal HE fuze was No 117 . In late 1944 a VT fuze T100 became available . Variants . No variants entered service although UK developed two self - propelled versions to prototype stage . The first in 1945 used the Crusader gun tractor ( developed from the Crusader tank to tow 17 pounder anti - tank guns ) . It was a turretless design with no casemate . The second , FV3805 , in the 1950s used a Centurion tank carriage , the gun being in a barbette mounting in a fully enclosed casemate .