List of autocannon
Revolver cannons
Table:
Caliber (mm)

Power source

Weapon name

Country of origin

Period

20
Internal

M39 cannon
United States
Cold War

20
Internal

Mauser MG 213
Nazi Germany
World War II

20
Internal

ShVAK cannon
Soviet Union
World War II

23
Internal

Rikhter R-23
Soviet Union
Cold War

27

Mauser BK-27
Germany
Cold War

30
External
Rheinmetall RMK30
Germany
Modern

30
Internal

ADEN cannon
United Kingdom
Cold War

30
Internal

DEFA cannon
France
Cold War

30
External

GIAT 30
France
Cold War

35
Internal

Oerlikon Millennium 35 mm Naval Revolver Gun System
Switzerland
Modern

Based on the given table along with the background passages listed at the end.

State the answer to the question: What is the country of origin for the weapon that took some time to develop , and was not used operationally until 1964 ? Output only the correct answer as {"answer": "YOUR ANSWER"}. Do not introduce information beyond the provided sources.

In guns , particularly firearms , caliber ( or calibre in British English ) is the specified nominal internal diameter of the gun barrel bore regardless of how or where the bore is measured and whether or not the finished bore matches that specification . It is measured in inches to an accuracy of hundredths or thousandths of an inch or in millimeters . For example , a .45 caliber firearm has a barrel diameter of roughly 0.45 inches ( 11 mm ) . Barrel diameters can also be expressed using metric dimensions . For example , a 9 mm pistol has a barrel diameter of about 9 millimeters . Due to the inaccuracy and imprecision of imperial dimensions converted to metric units , metric designations are typically far out of specifications published in decimal inches . True caliber specifications require imperial measure , and even when cartridge designations ( often mistakenly referred to as caliber ) only specify caliber to even tenths or hundredths of an inch , actual barrel/chamber/projectile dimensions are published to at least thousandths of an inch and frequently tolerances extend into ten-thousandths of an inch . In a rifled barrel , the distance is measured between opposing lands or between opposing grooves ; groove measurements are common in cartridge designations originating in the United States , while land measurements are more common elsewhere in the world . Measurements across the grooves are used for maximum precision because rifling and the specific caliber so-measured is the result of final machining process which cuts grooves into the rough bore leaving the lands behind . Good performance requires a concentric , straight bore that accurately centers the projectile within , in preference to a tight fit which can be achieved even with off-center , crooked bores that cause excessive friction , fouling and an out-of-balance , wobbling projectile in flight . While modern firearms are generally referred to by the name of the cartridge the gun is chambered for , they are still categorized together based on bore diameter . For example , a firearm might be described as a 30 caliber rifle , which could be any of a wide range of cartridges using a roughly 0.30 inches ( 7.6 mm ) projectile ; or a 22 rimfire , referring to any rimfire firearms firing cartridges with a .22 caliber projectile .
The M39 cannon is a 20 mm caliber single-barreled revolver cannon developed for the United States Air Force in the late 1940s . It was used on a number of fighter aircraft from the early 1950s through the 1980s .
The United States of America ( USA ) , commonly known as the United States ( U.S. or US ) or America , is a country consisting of 50 states , a federal district , five major self-governing territories , and various possessions . [ g ] At 3.8 million square miles ( 9.8 million km2 ) , it is the world 's third or fourth-largest country by total area [ b ] and is slightly smaller than the entire continent of Europe . Most of the country is located in central North America between Canada and Mexico . With an estimated population of over 328 million , the U.S. is the third most populous country in the world . The capital is Washington , D.C. , and the most populous city is New York City . Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago . European colonization began in the 16th century . The United States emerged from the thirteen British colonies established along the East Coast . Numerous disputes between Great Britain and the colonies led to the American Revolutionary War lasting between 1775 and 1783 , leading to independence . The United States embarked on a vigorous expansion across North America throughout the 19th century - gradually acquiring new territories , displacing Native Americans , and admitting new states - until by 1848 it spanned the continent . During the second half of the 19th century , the American Civil War led to the abolition of slavery in the United States . The Spanish-American War and World War I confirmed the country 's status as a global military power .
The Mauser MG 213 was a 20 mm aircraft-mounted revolver cannon developed for the Luftwaffe during World War II . It was never put into service , but the principles formed the basis for several post-war developments by the Allies . A 30 mm version was developed as the MG 213C or MK 213 and it was this that led to the British ADEN , French DEFA and American M39 cannon .
Nazi Germany is the common English name for Germany between 1933 and 1945 , when Adolf Hitler and his Nazi Party ( NSDAP ) controlled the country through a dictatorship . Under Hitler 's rule , Germany became a totalitarian state where nearly all aspects of life were controlled by the government . The official name of the state was Deutsches Reich ( German Reich ) until 1943 and Großdeutsches Reich ( Greater German Reich ) from 1943 to 1945 . Nazi Germany is also known as the Third Reich ( Drittes Reich ) , meaning Third Realm or Third Empire , the first two being the Holy Roman Empire ( 800-1806 ) and the German Empire ( 1871-1918 ) . The Nazi regime ended after the Allies defeated Germany in May 1945 , ending World War II in Europe . Hitler was appointed Chancellor of Germany by the President of the Weimar Republic , Paul von Hindenburg , on 30 January 1933 . The NSDAP then began to eliminate all political opposition and consolidate its power . Hindenburg died on 2 August 1934 and Hitler became dictator of Germany by merging the offices and powers of the Chancellery and Presidency . A national referendum held 19 August 1934 confirmed Hitler as sole Führer ( leader ) of Germany . All power was centralised in Hitler 's person and his word became the highest law . The government was not a coordinated , co-operating body , but a collection of factions struggling for power and Hitler 's favour . In the midst of the Great Depression , the Nazis restored economic stability and ended mass unemployment using heavy military spending and a mixed economy .
The ShVAK ( Russian : ШВАК : Шпитальный-Владимиров Авиационный Крупнокалиберный , Shpitalnyi-Vladimirov Aviatsionnyi Krupnokalibernyi , Shpitalny-Vladimirov large-calibre for aircraft ) was a 20 mm autocannon used by the Soviet Union during World War II . It was designed by Boris Shpitalniy and Semyon Vladimirov and entered production in 1936 . ShVAK were installed in many models of Soviet aircraft . The TNSh was a version of the gun produced for light tanks ( Russian : ТНШ : Tankovyi Nudelman-Shpitalnyi ) .
The Soviet Union , [ b ] officially known as the Union of Soviet Socialist Republics ( USSR or СССР ) , [ c ] was a federal sovereign state in northern Eurasia that existed from 1922 to 1991 . Nominally a union of multiple national Soviet republics , [ d ] in practice its government and economy were highly centralized . The country was a one-party state , governed by the Communist Party with Moscow as its capital in its largest republic , the Russian Soviet Federative Socialist Republic ( Russian SFSR ) . Other major urban centers were Leningrad , Kiev , Minsk , Tashkent , Alma-Ata , and Novosibirsk . It spanned over 10,000 kilometers ( 6,200 mi ) east to west across 11 time zones , and over 7,200 kilometers ( 4,500 mi ) north to south . Its territory included much of Eastern Europe , as well as part of Northern Europe and all of Northern and Central Asia . It had five climate zones : tundra , taiga , steppes , desert and mountains . The Soviet Union had its roots in the 1917 October Revolution , when the Bolsheviks , led by Vladimir Lenin , overthrew the Russian Provisional Government which had replaced the autocratic regime of Tsar Nicholas II during World War I . In 1922 , after a civil war ending in the Bolsheviks ' victory , the USSR was formed by a treaty which united the Russian , Transcaucasian , Ukrainian and Byelorussian republics . Following Lenin 's death in 1924 and a brief power struggle , Joseph Stalin came to power in the mid-1920s . Stalin formalized the Communist Party 's ideology of Marxism-Leninism and replaced the market economy with a command economy which led to a period of rapid industrialization and collectivization . During this period , rapid economic development resulted in dramatic improvements in the average standard of living , particularly in urban areas .
The Rikhter R-23 is an aircraft autocannon developed for the Soviet Air Force starting in the late 1950s . It was designed to be as short as possible to avoid problems found on high-speed aircraft when the guns were pointed into the airstream . The R-23 was a gas operated revolver cannon that used gas bled from holes in the barrel to provide the motive force . Firing up to 2,600 rpm , the R-23 was the fastest firing single-barrel cannon ever introduced into service . The R-23 took some time to develop , and was not used operationally until 1964 . It was used only in the tail turret of the Tu-22 , and experimentally on the Salyut 3 space station . Its role was taken over by the twin-barrel Gryazev-Shipunov GSh-23 . A modified version of the weapon was the only cannon to have been fired in space .
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 .
Germany ( German : Deutschland , German pronunciation : [ ˈdɔʏtʃlant ] ) , constitutionally the Federal Republic of Germany ( German : Bundesrepublik Deutschland , listen ( help·info ) ) , [ f ] is a country in Central and Western Europe . It borders Denmark to the north , Poland and the Czech Republic to the east , Austria and Switzerland to the south , France to the southwest , and Luxembourg , Belgium , and the Netherlands to the west . Germany includes 16 constituent states , covers an area of 357,386 square kilometres ( 137,988 sq mi ) , and has a largely temperate seasonal climate . With 83 million inhabitants , it is the second most populous state of Europe after Russia , the most populous state lying entirely in Europe , as well as the most populous member state of the European Union . Germany is a very decentralised country . Its capital and largest metropolis is Berlin , while Frankfurt serves as its financial capital and has the country 's busiest airport . Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity . A region named Germania was documented before AD 100 . Beginning in the 10th century , German territories formed a central part of the Holy Roman Empire . During the 16th century , northern German regions became the centre of the Protestant Reformation . After the collapse of the Holy Roman Empire , the German Confederation was formed in 1815 . The German revolutions of 1848-49 resulted in the Frankfurt Parliament establishing major democratic rights .
The RMK 30 ( Rückstoßfreie Maschinenkanone 30 ; recoilless autocannon ) is a recoilless 30 mm caliber autocannon firing caseless 30 × 250 mm ammunition cartridges . The gun was developed by the German company Mauser , which is now a subsidiary of the Rheinmetall group .
The Royal Small Arms Factory ADEN is a 30 mm revolver cannon used on many military aircraft , particularly those of the British Royal Air Force and Fleet Air Arm . Developed post-World War II primarily to meet British Air Ministry 's requirement for increased lethality in aircraft armament , the cannon was fired electrically and is fully automatic once it is loaded .
The United Kingdom of Great Britain and Northern Ireland , commonly known as the United Kingdom ( UK or U.K. ) or Britain , [ note 11 ] is a sovereign country located off the north­western coast of the European mainland . Existing under its current name since 1921 , the United Kingdom includes the island of Great Britain , the north­eastern part of the island of Ireland , and many smaller islands . Northern Ireland shares a land border with the Republic of Ireland . Otherwise , the United Kingdom is surrounded by the Atlantic Ocean , with the North Sea to the east , the English Channel to the south and the Celtic Sea to the southwest , giving it the 12th-longest coastline in the world . The Irish Sea separates Great Britain and Ireland . The total area of the United Kingdom is 94,000 square miles ( 240,000 km2 ) . The United Kingdom is a unitary parliamentary democracy and constitutional monarchy . [ note 12 ] The current monarch is Queen Elizabeth II , who has reigned since 1952 , making her the world 's longest-serving current head of state . The United Kingdom 's capital and largest city is London , a global city and financial centre with an urban area population of 10.3 million . Other major cities include Birmingham , Manchester , Glasgow , Leeds and Liverpool . The United Kingdom consists of four constituent countries : England , Scotland , Wales , and Northern Ireland . Their capitals are London , Edinburgh , Cardiff , and Belfast , respectively .
The DEFA cannon ( Direction des Études et Fabrications d'Armement ) is a family of widely used French-made aircraft revolver cannon firing standard 30 mm caliber NATO rounds .
France ( French : [ fʁɑ̃s ] ( listen ) ) , officially the French Republic ( French : République française , pronounced [ ʁepyblik fʁɑ̃sɛːz ] ( listen ) ) , is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories . [ XIII ] The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea , and from the Rhine to the Atlantic Ocean . It is bordered by Belgium , Luxembourg and Germany to the northeast , Switzerland and Italy to the east , and Andorra and Spain to the south . The overseas territories include French Guiana in South America and several islands in the Atlantic , Pacific and Indian oceans . The country 's 18 integral regions ( five of which are situated overseas ) span a combined area of 643,801 square kilometres ( 248,573 sq mi ) and a total population of 67.02 million ( as of July 2019 [ update ] ) . France is a unitary semi-presidential republic with its capital in Paris , the country 's largest city and main cultural and commercial centre . Other major urban areas include Lyon , Marseille , Toulouse , Bordeaux , Lille and Nice . France , including its overseas territories , has the most number of time zones of any country , with a total of 12 . During the Iron Age , what is now metropolitan France was inhabited by the Gauls , a Celtic people . Rome annexed the area in 51 BC , holding it until the arrival of Germanic Franks in 476 , who formed the Kingdom of Francia . The Treaty of Verdun of 843 partitioned Francia into East Francia , Middle Francia and West Francia . West Francia , which became the Kingdom of France in 987 , emerged as a major European power in the Late Middle Ages , following its victory in the Hundred Years ' War ( 1337-1453 ) .
The GIAT 30 is a series of 30 mm cannon developed to replace the DEFA 550 series weapons on French military aircraft . Introduced in the late 1980s , the GIAT 30 is a revolver cannon with electric ignition and automatic recocking . Unlike the DEFA cannon , the revolver chamber is electrically operated , rather than gas operated , improving both reliability and rate of fire . Two versions of the GIAT 30 are offered .
The Rheinmetall Oerlikon Millennium Gun or Rheinmetall GDM-008 is a close-in weapon system designed by Rheinmetall Air Defence AG ( formerly known as Oerlikon Contraves ) for mounting on ships . It is based on the 35/1000 revolver gun land based air defense system , and uses AHEAD ammunition .
Switzerland , officially the Swiss Confederation , is a country situated in the confluence of western , central , and southern Europe . [ note 4 ] It is a federal republic composed of 26 cantons , with federal authorities seated in Bern . [ note 1 ] Switzerland is a landlocked country bordered by Italy to the south , France to the west , Germany to the north , and Austria and Liechtenstein to the east . It is geographically divided among the Swiss Plateau , the Alps , and the Jura , spanning a total area of 41,285 km2 ( 15,940 sq mi ) , and land area of 39,997 km2 ( 15,443 sq mi ) . While the Alps occupy the greater part of the territory , the Swiss population of approximately 8.5 million is concentrated mostly on the plateau , where the largest cities are located , among them the two global cities and economic centres of Zürich and Geneva . The establishment of the Old Swiss Confederacy dates to the late medieval period , resulting from a series of military successes against Austria and Burgundy . Swiss independence from the Holy Roman Empire was formally recognized in the Peace of Westphalia in 1648 . The Federal Charter of 1291 is considered the founding document of Switzerland which is celebrated on Swiss National Day . Since the Reformation of the 16th century , Switzerland has maintained a strong policy of armed neutrality ; it has not fought an international war since 1815 and did not join the United Nations until 2002 . Nevertheless , it pursues an active foreign policy and is frequently involved in peace-building processes around the world . Switzerland is the birthplace of the Red Cross , one of the world 's oldest and best known humanitarian organisations , and is home to numerous international organisations , including the second largest UN office . It is a founding member of the European Free Trade Association , but notably not part of the European Union , the European Economic Area or the Eurozone .