{{Short description|WWII-era German 30mm aircraft autocannon}} {{Refimprove|date=February 2008}} {{Infobox weapon | name = MK 101 | image = File:Rheinmetall mk-101.jpg | caption = The MK 101 machine cannon | origin = Germany | type = Aircraft autocannon <!-- Type selection -->| is_ranged = yes | is_bladed = | is_explosive = yes | is_artillery = | is_vehicle = | is_UK = <!-- Service history --> | service = 1941–1945 | used_by = Nazi Germany | wars = World War II <!-- Production history -->| designer = Rheinmetall-Borsig | design_date = 1940 | manufacturer = Rheinmetall-Borsig | production_date = 1940–1945 | number = | variants = <!-- General specifications --> | weight = {{convert|139|kg|lb|abbr=on}} | length = {{convert|2592|mm|in|abbr=on}} | part_length = {{convert|1350|mm|in|abbr=on}} | width = | height = | crew = <!-- Ranged weapon specifications --> | cartridge = 30x184B, steel casing | action = Recoil operation | rate = 230–260 rounds/min | velocity = {{convert|900|m/s|ft/s|abbr=on|0}} | range = | max_range = | feed = | sights = <!-- Artillery specifications --> | breech = | recoil = | carriage = | elevation = | traverse = <!-- Bladed weapon specifications --> | blade_type = | hilt_type = | sheath_type = | head_type = | haft_type = <!-- Explosive specifications --> | diameter = | filling = | filling_weight = | detonation = | yield = <!-- Vehicle specifications --> | armour = | primary_armament = | secondary_armament = | engine = | engine_power = | pw_ratio = | suspension = | vehicle_range = | speed = }}

The '''MK 101''' is the designation of a 30&nbsp;mm autocannon used in German combat aircraft during World War II. Although accurate and powerful, with a high muzzle velocity, it was very heavy, with a low rate of fire, which limited its production.

==Development and use== Developed in 1935 by Rheinmetall-Borsig as a commercial venture as the MG-101 (later designated MK 101, with the "MK" abbreviating the term ''Maschinenkanone'', as an autocannon), the MK 101 cannon was a 30&nbsp;mm (1.18&nbsp;in), long-barreled automatic cannon capable of firing nine different types of 30x184B&nbsp;mm ammunition (ranging from basic high explosive to tungsten-cored armor-piercing rounds). Featuring pneumatic cocking and fired by percussion via an electrical solenoid, the MK 101 was recoil-operated. In operation, the barrel and bolt recoiled 30&nbsp;mm (1.18&nbsp;in) to the rear after each shot. The bolt locked via a Stange-type machined sleeve with internal interrupted threads, similar to some Solothurn weapons such as the 7.92&nbsp;mm (.312&nbsp;in) MG 30 light machine gun. The locking system was strong, but rate of fire was limited to a rather slow 230–260 rpm, which limited its use against other aircraft. Powerful and accurate for its day, it was carried primarily on the Henschel Hs 129 ground-attack aircraft, commencing in late 1941. Fed by a 10-round (early versions) or a 30-round box magazine, the MK 101 could penetrate 75&nbsp;mm (3&nbsp;in) of armor at 300&nbsp;m (330&nbsp;yd) range. The dozen examples created of the Heinkel He 177A-1/U2 ''Zerstörer'' ("Destroyer") experimental prototype attack aircraft used twinned MK 101s on a forward-aimed limited-traverse mount, located in the extreme lower nose at the front of a dramatically enlarged ''Bola'' inverted-casemate gondola emplacement under the nose, and was intended for anti-ship and possible "train-busting" use, but was never deployed in combat. When it was used from beneath an Hs 129's central fuselage as a ventral gun pod-mounted anti-tank weapon, the MK 101's tungsten-cored AP round was capable of penetrating the turret and side armor of the Soviet KV-1 heavy tank.<ref>Kay, Antony L. and Smith, John R., ''German aircraft of the Second World War: Including Helicopters and Missiles'', Naval Institute Press (2002), {{ISBN|1-55750-010-X}}, 9781557500106, p. 169</ref> An electrically-fired version of the MK 101 cannon was later developed and designated the MK 103.

==See also== *MK 103 cannon *MK 108 cannon

==References== {{reflist}} {{WWIIGermanAerialWeapons}} Category:30 mm artillery Category:Autocannon Category:Aircraft guns Category:Rheinmetall Category:Weapons and ammunition introduced in 1940