The BK 27 (also BK27 or BK-27) (German abbreviation for Bordkanone, "on-board cannon") is a 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 series of 27×145 mm cartridges with a typical projectile weight of 260 g (9.2 oz), and a total weight for the complete round of 516 g (1.14 lb).

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(+/− 100 rpm).

Operators

thumb|MLG 27 mounted on board an [[Elbe-class replenishment ship|Elbe-class replenishment ship of the German Navy]]

thumb|MLG 27 on board a [[Berlin-class replenishment ship|Berlin-class replenishment ship of the German Navy]]

thumb|Map with operators of the BK-27 in blue and former operators in red

Current operators

;

:Algerian Navy

;

:Austrian Air Force:

;

:Brazilian Air Force:

:* Saab JAS 39 Gripen E/F

;

:Royal Brunei Navy

:* 4 × with 1 × each

:* 4 × Ijtihad class with 1 × each

;

:Discovery Air Defence Services:

:* Alpha Jet A (former Luftwaffe and QinetiQ Aircraft)

;

:Czech Air Force:

:* Saab JAS 39 Gripen C/D

;

:German Air force:

:* Eurofighter Tranche 1

:* Eurofighter Tranche 2

:* Eurofighter Tranche 3

:* Eurofighter Tranche 4

:* Eurofighter ECR

:* Panavia Tornado IDS

:* Panavia Tornado ECR

:German Navy:

:* 4 × (F123) with 2 × each

:* 3 × (F124) with 2 × each

:* 4 × (F125) with 2 × each

:* 6 × Niedersachsen class (F126) with 2 × each

:* 10 × (K130) with 2 × each

:* 2 × (Type 352) to be upgraded with 2 × each

:* 8 × (Type 322) to be upgraded with 1 × each

:* 3 × with 4 × each

:* 2 × (Type 404) to be upgraded with 2 × each

;

:Hungarian Air Force:

:* Saab JAS 39 Gripen C/D

;

:Italian Air force:

:* Eurofighter Tranche 1

:* Eurofighter Tranche 2

:* Eurofighter Tranche 3

:* Eurofighter Tranche 4

:* Panavia Tornado IDS

:* Panavia Tornado ECR

;

:Royal Air Force of Oman:

:* Eurofighter Tranche 3

;

:Royal Saudi Air Force:

;

:South African Air Force:

:* Saab JAS 39 Gripen C/D

;

:Spanish Air Force:

;

:Royal Air Force:

:German Navy:

:* 8 × (F122) with 2 × each

;

:Portuguese Air Force:

:* Alpha Jet A (former Luftwaffe aircraft, retired in January 2018)

;

:Royal Saudi Air Force:

:* Panavia Tornado ADV (retired in 2006)

;

:Swedish Air Force:

:* Saab JAS 39 Gripen A/B

;

:Royal Air Force:

Specifications

thumb|Helicopter-mounted Mauser BK-27

<small>Data from Jane's Information Group