BK-27 German 27mm Revolver Cannon

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 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). 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. 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, but instead elected for 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 half second 4 kg of projectiles in contrast to the 2 kg of the M61 Vulcan which also needs about 25 kW electrical power on the maximum fire rate. As for ammunition types the gun mainly fires mine shells as these have the best effect against aircraft but the gun also has access to several types of armor piercing shells like the frangible armour piercing shell named Fap 27 mm x 145 mm ammunition/peb327 (DM103).