BL 5.5-inch Medium Gun

BL 5.5 inch Medium Gun Mk 3
BL 5.5 inch Mk 3 at The Artillery Museum of Finland
Type	Medium gun
Place of origin	United Kingdom
Service history
In service	1941-1980 (UK)
Used by	United Kingdom France Poland Australia Canada India Portugal Myanmar Iraq Malaysia Namibia Oman Pakistan South Africa New Zealand
Wars	World War II, Korean War, Yemen, Borneo Conflict, Angolan Civil War
Production history
Produced	1941-1945
Specifications
Weight	13,647 lbs (6,190 kg)
Barrel length	13 ft 9 in (4.19 m) L/30
Width	8 ft 4 in (2.54 m)
Crew	10
Shell	HE shell: 100 lb (45.5 kg) and 82 lb (37 kg)
Calibre	5.5 inch (140 mm)
Breech	Welin breech and Asbury mechanism
Recoil	Hydro-pneumatic
Carriage	Split trail
Elevation	-5° to 45°
Traverse	30° left and right
Rate of fire	2 rpm
Muzzle velocity	100lb shell: 1,675 ft/s (511 m/s) 82lb shell: 1,950 ft/s (590 m/s)
Maximum firing range	100lb shell: 16,200 yd (14,813 m) 82lb shell: 18,100 yd (16,550 m)
Sights	Probert pattern reciprocating and calibrating

The BL 5.5 inch Gun was a British artillery gun introduced during the middle of the Second World War to equip medium batteries.

In January 1939 a specification was issued for a gun to replace the 6 inch 26 cwt howitzers 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, and was used by the Pakistan Army against India in the mountains of Kashmir during the Kargil War of 1999.

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. Approximately 72 are still held in reserve by the South African Army.

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 Leyland Martian 6x6 Medium Artillery Tractor .