Mauser BK-27

The BK 27 (also BK27 or BK-27) (German acronym for Bordkanone, "on-board cannon") is a 27 mm (1.063 in) caliber revolver cannon manufactured by Mauser (now part of Rheinmetall) of Germany. It was developed in the late 1960s for the MRCA (Multi Role Combat Aircraft) program that ultimately became the Panavia Tornado.

The BK 27 is a gas-operated cannon firing a new series of 27x145 mm projectiles with a typical weight of 260 g (9.2 oz). Most models use a linked feed system for the ammunition; however, the Eurofighter Typhoon makes use of a specially developed variant of the BK 27 that uses a linkless feed system instead, which is intended to improve reliability.

Mauser BK-27
Class Vehicle
Type Other
Manufacturer Mauser
Origin Germany
Country Name Origin Year
Germany 1977
Country Name Operational Year Retirement Year
Austria View
Bolivia View
Cameroon View
Canada View
Germany View
Hungary View
Italy View
Portugal View
Saudi Arabia View
South Africa View
Spain View
Sweden View
Thailand (Siam) View
United Arab Emirates View
United Kingdom - UK (Great Britain) View
Czech Republic View
ManufacturerName Production From Production To Quantity
Mauser 1977 3100 View

The Mauser BK 27 is used in the Panavia Tornado, the Alpha Jet, the JAS 39 Gripen, and the Eurofighter Typhoon. At one time the USAF was considering to license its production for the F-35 Lightning II joint strike fighter, but those plans have been cancelled in favour of the GAU-22/A.

Rheinmetall has also developed remote controlled naval versions, the MN 27 GS and the MLG 27 fully automatic naval guns, which are installed on many ships of the German Navy. Ninety-nine MLG 27s have been ordered by the German Navy so far. The cannon is a single-barrel, high performance, breech-cylinder gun operated by a fully automatic electrically fired gas-operated system at a selective rate of 1000 or 1700 rounds per minute. The Mauser BK 27 utilizes pyrotechnic cocking charges to cycle the action.

The BK27 has a much lower nominal fire rate than the M61 Vulcan, but its fire rate is constant throughout shooting due to the fact the cannon need not spin up. As a result, in conjunction with the higher caliber, the Mauser BK 27 fires in the first second 4 kg of projectiles in contrast to the 2 kg of the M61 Vulcan which also needs about 25kW electrical energy on the maximum fire rate.

Type Revolver cannon
Place of origin Germany
Service history
Used by See users
Production history
Designer Mauser (now Rheinmetall)
Designed 1976
Manufacturer Mauser (now Rheinmetall)
Produced 1977-present
Number built 3,100~
Weight 100 kg (220 lb 7 oz)
Length 2.31 m (7 ft 7 in)
Barrel length 1.73 m (5 ft 8 in)
Shell 27x145 mm
Caliber 27 mm (1.063 in) caliber
Barrels Single barrel
Action revolver
Rate of fire 1,000-1,700 rpm (+/- 100rpm), selectable
Muzzle velocity 1,100 m/s (3,600 ft/s)[1]


  • Type: single-barrel revolver cannon
  • Caliber: 27 mm x 145 (1.063 in)
  • Operation: revolver
  • Length: 2.31 m (7 ft 7 in)
  • Weight (complete): 100 kg (220 lb)
  • Rate of fire: 1,700 rpm (+/- 100rpm)
  • Muzzle velocity: 1,100 m/s (3,600 ft/s)
  • Muzzle energy: ~157,300 Joules
  • Projectile weight: 260 g (9.2 oz)

End notes