Bofors 57 mm gun

The Bofors 57 mm guns are a series of dual-purpose naval guns designed and produced by the Swedish arms manufacturer AB Bofors (since March 2005 part of BAE Systems AB), designed in 1964 as a revision of the 57 mm lvakan M/50 used on the Halland class destroyers. Production of the baseline 57 mm Mark 1 variant began in 1966 and was initially used to equip smaller coastal patrol craft and fast attack craft . The gun is remotely controlled, usually by a fire-control computer but, as a redundancy measure, the crew can also train and aim the gun using instrument panels that are either on or in direct contact with the gun. Although the Swedish Navy is the primary user of the gun, it has been exported widely by Bofors Defence for use by the navies of Brunei, Canada, Croatia, Finland, Indonesia, Ireland, Malaysia, Mexico, Montenegro, Singapore, Thailand and the United States.

The gun was upgraded and improved several times, first the Mark 2 in 1981 which drastically lowered the weight as well as introduced new servo stabilisers. The Mark 3 came in 1995 with modifications made to enable the smart ammunition developed.

Bofors 57 mm gun
Class Vehicle
Type Other
Manufacturer Bofors
Production Period 1966 - 2000
Origin Sweden
Country Name Origin Year
Sweden 1966
Country Name Operational Year Retirement Year
Bangladesh View
Brunei View
Canada View
Croatia View
Finland View
Indonesia View
Ireland View
Malaysia View
Mexico View
Montenegro View
Singapore View
Sweden 1966 View
Thailand (Siam) View
United States of America View
ManufacturerName Production From Production To Quantity
Bofors 1966 2000 View
United Defense 2000 2005 View
BAE Systems AB 2005 View

The baseline version of the Bofors 57 mm (2.2 in) L70 gun was the Mark 1, first introduced into service with the Spica-class fast attack craft (FAC) of Swedish Navy in 1966, it has a rate of fire of 200 rounds per minute and a 40-round magazine in the gun turret with a further 128 rounds stowed inside. With minor modifications, the Mark 1 guns could use ammunitions developed for the Mark 2 gun.

The Mark 2 was designed in 1981 but introduced into service with the Stockholm-class corvette—HMS Stockholm (K11) in 1985 (sister ship HMS Malmö (K12) was built in 1984 but armed with the older Mk 1, subsequently retrofitted with the Mk 2 in 2009), the rate of fire was slightly increased to 220 rounds per minute. Also, it featured a new light weight gun turret with a new gun barrel that was forged from monobloc steel (this eliminated the need to use a water jacket for gun barrel cooling during firing) and a new servo drive/servomechanism system (for faster reaction time and better gun aiming and control). According to Bofors, the new servo system allowed the Mk 2 to be both accurate and agile enough for use against sea skimming anti-ship missiles and that it could put more explosives into a surface target within a thirty second window than any naval gun with a calibre smaller than 100 mm (3.9 in).

The latest development is the Mark 3, which was designed in 1995 but introduced into service with the Visby-class corvette—fitted on HMS Visby (K31) in 2000. This new design retained the Mark 2 gun turret, rate of fire and ammunition capacity and has another 1,000 rounds stowed in the standby rack beneath deck. A small radome has been added above the gun barrel and is used for measuring the muzzle velocity of the departing projectiles for fire-control purposes, usually but not necessarily with the new Bofors 57 mm 3P all-target programmable ammunition. Also, a new optional low radar profile (also known as low radar cross-section, or RCS) stealth mounting was developed, this allows the gun to be hidden from radar and plain sight when not in use.

In American service, the United States Navy has designated the Mark 3 as the Mark 110 Mod 0 57mm gun. According to a BAE press release dated 1 August 2005, the Mark 110 would be manufactured at the BAE Systems facility in Louisville, Kentucky.

Type Naval artillery
Place of origin Sweden
Service history
In service 1966–present
Used by See users
Production history
Designer Bofors Defence
Designed Mark 1: 1964
Mark 2: 1981
Mark 3: 1995
Manufacturer Bofors Defence (1966–2000)
United Defense (2000–2005)
BAE Systems AB (2005 onwards)
Produced Mark 1: 1966
Mark 2: 1985
Mark 3: 2000
Variants See variants
Specifications
Weight Mark 3: 14,000 kg (31,000 lb) (weight including 1,000 rounds onboard)
6.5 kg (14 lb) (complete round)
Barrel length Bore length: 3,990 mm (157.09 in)
Without flash hider: 4,045 mm (159.25 in)
With flash hider: 4,345 mm (171.06 in)
Shell 57 mm × 438 mm
6.1 kg (13 lb) complete round
2.4 kg (5.3 lb) pre-fragmented shell
Caliber 57 mm/70 caliber
Barrels Single barrel (progressive RH parabolic twist, 24 grooves)
Action Electronic firing
Elevation Mark 1: -10°/+78° (40°/s)
Mark 2: -10°/+75° (40°/s)
Mark 3: -10°/+77° (44°/s)
Traverse Full 360°:
Marks 1 & 2: 55°/s
Mark 3: 57°/s
Rate of fire Mark 1: 200 rounds/min
Marks 2 & 3: 220 rounds/min
Muzzle velocity 1,035 m/s (3,400 ft/s) (HE round)
Effective firing range 8,500 m (9,300 yd) (HE round)
Maximum firing range 17,000 m (19,000 yd) (HE round at 45°)
Feed system Magazine:
Mark 1: 40 ready rounds, 128 rounds in ready racks in mount
Mark 2: 120 ready rounds, up to 40 rounds in dual hoists
Mark 3: 120 ready rounds, up to 40 rounds in dual hoists, 1,000 rounds in mounting
Sights Gyro-stabilized in local control.

End notes