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Surface Vessel Weapon System Bofors 40/L70 AA gun |
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The Bofors 40 mm Automatic Gun L/70, (Bofors 40 mm L/70, Bofors 40
mm/70, Bofors 40/70), is a multi-purpose autocannon developed by the
Swedish arms manufacturer AB Bofors (today BAE Systems Bofors)
during the second half of the 1940s as a modern replacement for
their extremely successful World War II-era Bofors 40 mm L/60
gun-design. It was initially intended as a dedicated anti-aircraft weapon, being sold as Bofors 40 mm Automatic A.A. Gun L/70, but has since its conception been redeveloped into a dedicated multi-purpose weapon capable of firing both sabot projectiles and programmable ammunition. The Bofors 40 mm L/70 design never achieved the same popularity and historical status as the original L/60 design but has still seen great export and popularity to this day, having been adopted by around 40 different nations and even being accepted as NATO-standard in November 1953. It is still being produced and sold (since March 2005 by BAE Systems AB), and several variants exist for both field and naval applications. The Bofors 40 mm L/70, like most Bofors autocannons, is based on the same core action as the original Bofors 40 mm Automatic Gun L/60, basically being a fire on closing, self-ejecting gun with a recoil-operated autoloader in the same receiver, and thus looks visually similar. Despite this, the Bofors 40 mm L/70 is a separate design with a number of major changes compared to its predecessor. The most superficial changes are the longer L/70 barrel, double cooling vents on the jacket and the fact that the weapon comes chambered for a more powerful 40×365mmR cartridge (vs 40x311mmR for the Bofors 40 mm L/60). Most importantly however is the new ejection system which ejects the empty cartridge cases out from the opposite side to the feed, compared to the ejecting system on the 40 mm L/60 which ejects the cases straight out the back of the gun. This system change almost doubled the mechanical rate of fire from the previous system. By the end of World War II, the speed of jet aircraft enabled them to withdraw quickly out of range of the Bofors; a longer range was necessary. A higher rate of fire was also required, increasing the number of rounds fired over the period of an engagement. Bofors considered either updating the 40 mm, or alternatively making a much more powerful 57 mm design. In the end they did both. The new 40 mm design used a larger 40x365R round firing a slightly lighter 870 g shell at a much higher 1,030 m/s (3,379 fps) muzzle velocity. The rate of fire was increased to 240 rounds per minute (4.0 rounds per second). Additionally, the carriage was modified to be power-laid, the power being supplied by a generator placed on the front of the carriage. The first version was produced in 1947, accepted in 1948 as the "40 mm lvakan m/48", and entered Swedish service in 1951. Additional changes over the years have increased the firing rate first to 300 rpm (5.0 rounds per second), and later to 330 rpm (5.5 rps). The introduction of a 40mm proximity fuzed round in the early 1970s was another improvement. Variants: Bofors SAK 40/L70 315 Bofors SAK 40/L70 350 Bofors SAK 40/L70 520 Bofors 40/L70 Mod. 1958 Bofors SAK 40/L70 600 Sea Trinity Bofors 40/L70 Mk.3 BAE/Bofors 40/L70 Mk.4 Technical data: Manufacturer: Bofors, BAE Systems Caliber: 40 mm (1.57 inches) Cartridge: 40 x 365 mm Projectile length: 21 cm (8.3 in) Complete round length: 53,44 cm (21.4 in) Barrel length: 2,800 mm (9 ft 2 in) Muzzle velocity: ≈1,000 m/s (3300 ft/s) Rate of fire: 240, 300, 330 rounds/min Max. firing range: 12,500 m (41,000 ft) Ammunition: PFHE (Prefragmented High-Explosive) HE-T (High-Explosive Tracer) 40 3P (Programmable) |
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 Bofors 40/L70 AA gun aboard a Swedish Navy Koster class mine countermeasures vessel  Bofors 40/L70 AA gun aboard a Swedish Navy Koster class mine countermeasures vessel  Bofors 40/L70 AA gun aboard a Swedish Navy Koster class mine countermeasures vessel  Bofors 40/L70 AA gun aboard HSwMS Carlskrona (P04)  Bofors 40/L70 AA gun aboard HSwMS Carlskrona (P04) Bofors 40/L70 AA gun aboard a Finnish Navy Katanpää class mine countermeasure vessel  Bofors 40/L70 AA gun aboard a Finnish Navy Katanpää class mine countermeasure vessel  Bofors 40/L70 AA gun aboard a Finnish Navy Katanpää class mine countermeasure vessel  Bofors 40/L70 AA gun aboard a Finnish Navy Katanpää class mine countermeasure vessel  Bofors 40/L70 AA gun aboard a Swedish Navy Göteborg class Corvette  Bofors 40/L70 AA gun aboard a Swedish Navy Göteborg class Corvette  Bofors 40/L70 AA gun aboard a Swedish Navy Göteborg class Corvette  Bofors 40/L70 AA gun aboard Finnish Navy Minelayer Pohjanmaa (01)  Bofors 40/L70 AA gun aboard Finnish Navy Minelayer Pohjanmaa (01)  Bofors 40/L70 AA gun aboard Finnish Navy Minelayer Pohjanmaa (01) |
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