Bofors 57 mm Naval Automatic Gun L/70

Bofors 57 mm Naval Automatic Gun L/70
A Mk 110 57 mm gun on the littoral combat ship USS Freedom
TypeNaval artillery
Place of originSweden
Service history
In service1971–present
Used bySee users
Production history
DesignerBofors Defence
Designed
  • Mark 1: 1970
  • Mark 2: 1981
  • Mark 3: 1995
Manufacturer
Produced
  • Mark 1: 1970
  • Mark 2: 1985
  • Mark 3: 2000
VariantsSee variants
Specifications
MassMark 3: 14,000 kg (31,000 lb) (weight including 1,000 rounds onboard, each weighing 6.5 kg (14 lb) per 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)

Shell57 × 438 mm R (m/70)
6.1 kg (13 lb) complete round
2.4 kg (5.3 lb) pre-fragmented shell
Caliber57 mm/70 caliber
BarrelsSingle barrel (progressive RH parabolic twist, 24 grooves)
ActionElectronic firing
Elevation
  • Mark 1: −10°/+78° (40°/s)
  • Mark 2: −10°/+75° (40°/s)
  • Mark 3: −10°/+77° (44°/s)
TraverseFull 360°:
  • Mark 1: 55°/s
  • Mark 2: 55°/s
  • Mark 3: 57°/s
Rate of fire
  • Mark 1: 200 rounds/min
  • Mark 2: 220 rounds/min
  • Mark 3: 220 rounds/min
Muzzle velocity1,035 m/s (3,400 ft/s) (HE round)
Effective firing range8,500 m (9,300 yd) (HE round)
Maximum firing range17,000 m (19,000 yd) (HE round at 45°)
Feed systemMagazine:
  • 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
SightsGyro-stabilized in local control.

The Bofors 57 mm Naval Automatic Gun L/70 (Swedish: 57 mm sjöautomatkanon L/70 (57 mm SAK 70)),[1][2] among other names, is 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 the late 1960s as a replacement design for the twin barreled Bofors 57 mm Naval Automatic Gun L/60. The gun is remotely controlled by a fire-control computer but can as a redundancy measure also be operated manually by crew using instrument panels either on or in direct contact with the gun.[3]

The gun has been upgraded and improved several times:

  • Mk1 – The baseline Mark 1 variant began production in 1970 and was initially used to equip smaller coastal patrol craft and fast attack craft.
  • Mk2 – The improved Mark 2 variant came in 1981 and drastically lowered the weight as well as introduced new servo stabilizers.
  • Mk3 – The improved Mark 3 variant came in 1995 and primarily features the ability to use programmable ammunition.[3]

While the 57 mm cannon may not seem as powerful as larger naval guns, such as the OTO Melara 76 mm, some of its performances are comparable; given its rate of fire and amount of explosive per shell, the Bofors gun actually achieves a higher amount of "explosive fired per second" than the 76 mm.[4]

Although the Swedish Navy has been 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.

  1. ^ "Bofors automatic 57mm Dual-Purpose guns". tfd.chalmers.se. Archived from the original on 2007-05-14. Retrieved 2021-10-22.
  2. ^ "030306_SAK57_Mk3.pdf" (PDF). boflv.se. Bofors Luftvärnsförening (Bofors Anti-Aircraft Association). 2003. Archived (PDF) from the original on 2010-09-11. Retrieved 2021-11-19.
  3. ^ a b "Sweden 57 mm/70 (2.25") SAK Marks 1, 2 and 3 / United States 57 mm/70 (2.25") Mark 110 Mod 0". NavWeaps.Com. 10 April 2008. Archived from the original on 3 September 2011. Retrieved 22 September 2011.
  4. ^ French Navy FTI Frigate: From 57mm to 127mm, Naval Gun System Choice Still Open Archived 2016-10-31 at the Wayback Machine - Navyrecognition.com, 28 October 2016