Weapon Name- Mauser BK-27
Round Type- 27×145 mm
Over-all length- 2.31 m (7 ft 8 in)
Barrel length- 1.73 m (5 ft 8 in)
Weight- 100-150 kg (220-320 lb)
Rate of Fire- 1,000–1,700 rpm (+/− 100 rpm), selectable
Feed Mechanism- Linkless Belt
Round Capacity- 150+
Effective Range- 2500 meters
Range- 4000 meters
Accuracy- 1.5 MOA
Accessories- N/A
Quick switch firing mechanism- N/A
Scope/Sights- N/A
Muzzle Velocity- 1,100 m/s - 1,250 m/s - 260 g (9.2 oz) (157,300 Joules), (203,125 joules)
Firing System- Revolver cannon
Miscellaneous/electronic information-
Basic Information
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 516g (1.14lbs). 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 cartridge has two variants, a lower velocity 1100 m/s and a higher velocity 1250 m/s cartridge, using the same bullet weight. This version of the mauser BK-27 utilizes a heavier longer barrel, which can handle higher pressure cartridges, generating slightly more power.
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 a 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.
The weapon uses a detachable polygonal cobalt chrome "flow formed" right hand turn barrel; the barrel is made of an alloy that contains more than 50 percent cobalt. The barrel is roughly 13% heavier than standard steel barrels, but is more erosion and corrosion-resistant and is designed to retain high strength during long-term exposure to high temperatures. Cobalt alloys are frequently used in the aerospace industry, such as the hot-gas section of turbine engines. A proof of concept M240 7.62mm x 51mm NATO barrel, in practice, had 24,000 rounds test-fired through it, causing it to reach temperatures of 1,100 degrees, without failure. A steel barrel would have failed under such treatment. In addition, the weapon utilizes a progressive, gain twist, which reduces barrel pressure and wear, particularly on the first and last 4 inches of the barrel. The barrel has an extremely long life, but more importantly can withstand extremely high temperatures, allowing for the extremely high rate of fire, 1000 to 1700 RPM, to be maintained for much longer periods of time even with a single barrel, allowing it to achieve a rate of fire similiar to many miniguns without the size and complexity. The smaller size and weight of the overall firearm, and the heat resistant barrel, allows it to easily take the place of many smaller chainguns, such as 20mm and 25mm chainguns, and remain competitive with larger 30mm chainguns, in a much smaller package with a higher rate of fire. In comparison, a 25mm Bushmaster is approximately 260 pounds, while the smallest variant of the Bk-27 is 220 pounds, and yet it fires a round with 160,000 joules, in comparison to the 25mm at 100,000 joules. With two guns, it easily replaces many miniguns in terms of rate of fire, but retains the maneuverability and small size of a smaller weapon.
