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40mm Bofors

Bofors 40 mm gun
Bofors-p004596.jpg
Bofors 40 mm/L60. This example includes the British-designed Stiffkey Sight, being operated by the gun layer standing to the right of the loader (turned sideways). It operates the trapeze seen above the sights, moving the sights to adjust for lead.
Type
Place of origin Sweden
Service history
In service 1934–present
Used by See users
Wars World War II,
Indo-Pakistani wars and conflicts,
Arab-Israeli conflict,
Korean War,
Indonesia-Malaysia confrontation,
Vietnam War,
Yom Kippur War,
South African Border War,
Falklands War,
Lebanese Civil War,
Gulf War,
Yugoslav wars
Production history
Designer Bofors Defence
Designed 1930
Manufacturer Bofors Defence (1932–2000)
United Defense Industries (2000–2006)
BAE Systems AB (2006 onwards)
Produced 1932–present
Variants See variants
Specifications
Weight

L/60: 1,981 kg (4,367 lb)

L/70: 5,150 kg (11,350 lb)
Crew dependent on use

Shell Complete round:
L/60 40×311mmR (1.57 in)
L/70 40×364mmR
Caliber 40 mm L/60–70 (actual length varies from 56–70 calibers, based on model)
Carriage 522 kg (1,151 lb)
Elevation L/60: -5°/+90° (55°/s)
L/70: -20°/+80° (57°/s)
Traverse Full 360°
L/60: 50°/s
L/70: 92°/s
Rate of fire L/60: 120 round/min
L/70: 330 round/min
Muzzle velocity L/60: 881 m/s (2,890 ft/s)
L/70: 1,021 m/s (3,350 ft/s)
Maximum firing range L/60: 7,160 m (23,490 ft)
L/70: 12,500 m (41,000 ft)

L/60: 1,981 kg (4,367 lb)

The Bofors 40 mm gun, often referred to simply as the Bofors gun, is an anti-aircraft/multi-purpose designed in the 1930s by the Swedish arms manufacturer AB Bofors. It was one of the most popular medium-weight anti-aircraft systems during World War II, used by most of the western Allies as well as by the Axis powers. A small number of these weapons remain in service to this day, and saw action as late as the Gulf War.

In the post-war era the original design was not suitable for action against jet powered aircraft, so Bofors introduced a new model of significantly more power, the 40 mm L/70. In spite of sharing almost nothing with the original design other than the calibre and the distinctive conical flash hider, this weapon is also widely known simply as "the Bofors". Although not as popular as the original L/60 model, the L/70 remains in service to this day, especially as a multi-purpose weapon for light armored vehicles, as on the CV 90.

Bofors itself has been part of BAE Systems AB since March 2005.

The Swedish Navy purchased a number of 2 pounder Pom-Poms from Vickers as anti-aircraft guns in 1922. The Navy approached Bofors about the development of a more capable replacement. Bofors signed a contract in late 1928. Bofors produced a gun that was a smaller version of a 57 mm (6-pounder) semi-automatic gun developed as an anti-torpedo boat weapon in the late 19th century by Finspong. Their first test gun was a re-barreled Nordenfelt version of the Finspong gun, to which was added a semi-automatic loading mechanism.

Testing of this gun in 1929 demonstrated that a problem existed feeding the weapon in order to maintain a reasonable rate of fire. A mechanism that was strong enough to handle the stresses of moving the large round was too heavy to move quickly enough to fire rapidly. One attempt to solve this problem used zinc shell cases that burned up when fired. This proved to leave heavy zinc deposits in the barrel, and had to be abandoned. In the summer of 1930 experiments were made with a new test gun that did away with controlled feed and instead flicked the spent casing out the rear whereafter a second mechanism reloaded the gun by "throwing" a fresh round from the magazine into the open breech. This seemed to be the solution they needed, improving firing rates to an acceptable level, and the work on a prototype commenced soon after.


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