Question: What was the calibre of the controversial rifle invented by Sir Charles Henry Augustus Frederick Lockhart Ross?

full_context: Document 1: Ross rifle: The Ross rifle was a straight-pull bolt action .303 inch-calibre rifle produced in Canada from 1903 until 1918.
Document 2: Mannlicher M1886: The Repeating Rifle Model 1886 commonly known as Mannlicher Model 1886 was a late 19th-century Austrian straight-pull bolt-action rifle, adopted in 1886. It used a wedge-lock straight pull action bolt. It was the first straight-pull bolt-action service rifle of any nation.
Document 3: K31: The Karabiner Model 1931 (K31) is a magazine-fed, straight-pull bolt action rifle. It was the standard issue rifle of the Swiss armed forces from 1933 until 1958 though examples remained in service into the 1970s. It has a 6-round removable magazine, and is chambered for the 7.5×55mm Swiss "Gewehrpatrone 1911" or GP 11, a cartridge with ballistic qualities similar to the 7.62×51mm NATO/.308 Winchester cartridge. Each rifle included a 6-round detachable box magazine with matching stamped serial number. A charger is used to load the magazine from the top of the receiver.
Document 4: Sir Charles Ross, 9th Baronet: Sir Charles Henry Augustus Frederick Lockhart Ross, 9th Baronet (4 April 1872 – 29 June 1942) was a Scottish inventor and commercial entrepreneur who invented the innovative and often controversial straight-pull actioned Ross rifle.
Document 5: Robert Charles: Robert Charles (1865–1900) was an African American living in New Orleans whose armed resistance to unlawful arrest and shooting of police officers sparked a major race riot in 1900; known as the Robert Charles riots.
Document 6: Lee–Enfield: The Lee–Enfield is a bolt-action, magazine-fed, repeating rifle that was the main firearm used by the military forces of the British Empire and Commonwealth during the first half of the 20th century. It was the British Army's standard rifle from its official adoption in 1895 until 1957. . It is often referred to as the "SMLE," which is short for the common "Short Magazine Lee-Enfield" variant.
Document 7: Bolt action: Bolt action is a type of firearm action in which the weapon's bolt is operated manually by the opening and closing of the breech (barrel) with a small handle, most commonly placed on the right-hand side of the weapon (for right-handed users). As the handle is operated, the bolt is unlocked, the breech is opened, the spent cartridge case is withdrawn and ejected, the firing pin is cocked (this occurs either on opening or the closing of the bolt, depending on design), and finally a new round/cartridge (if available) is placed into the breech and the bolt closed. Bolt-action firearms are most often rifles, but there are some bolt-action shotguns and a few handguns as well. Examples of this system date as far back as the early 19th century, notably in the Dreyse needle gun. From the late 19th century, all the way through both World Wars, the bolt-action rifle was the standard infantry firearm for most of the world's militaries.
Document 8: .280 Ross: The .280 Ross, also known as the .280 Nitro, .280 Rimless Nitro Express Ross (CIP) and .280 Rimless cartridge, is an approximately 7mm bullet diameter rifle round developed in Canada by F.W. Jones as a consultant to Sir Charles Ross, 9th Baronet, and his Ross Rifle Company of Quebec, Canada for use as a Canadian military cartridge as a replacement for the .303 British, and in a civilianised and sporterised version of his controversial Mark II and Mk III Ross rifle, and first commercially produced by Eley Brothers of London, England, in late 1907.
Document 9: John H. Ross: John Henry Ross (June 8, 1918 – August 9, 2013) was a decorated World War II pilot who flew 96 missions for the 22nd Reconnaissance Squadron as part of the 7th Reconnaissance Group in the 8th Air Force. Ross flew the Lockheed P-38 Lightning as a photo-recon pilot out of RAF Mount Farm in England during the war. He received 11 medals and 2 Distinguished Flying Crosses.
Document 10: Ross Priory: Ross Priory is an early 19th-century country house located west of Gartocharn, West Dunbartonshire, on the south shore of Loch Lomond, Scotland. From the 14th century the estate, known as The Ross, was owned by a branch of the Buchanan family of Buchanan Castle, who built a house here in 1695. The present house is the result of remodelling by James Gillespie Graham and was complete in 1816. The term "priory" does not imply ecclesiastical provenance, but is simply a 19th-century romantic affectation. Sir Walter Scott spent time at Ross Priory in the years following the rebuilding. It was owned by subsequent members of the Leith-Buchanan family until the later 20th century. In 1973 it was sold to Strathclyde University and now serves as a recreational and conference centre.
Document 11: Charles Ross (historian): Charles Derek Ross (1924 – 1986) was an English historian of the Late Middle Ages. He was educated at Wakefield Grammar School and Brasenose College, Oxford, where he completed a doctoral thesis on the baronage in Yorkshire in the early fifteenth century under the supervision of K.B. McFarlane. He published predominantly on the history of the later medieval English nobility, royalty, and the Wars of the Roses. Originally teaching alongside Margaret Sharp (daughter of T.F. Tout), he became reader and then Professor of Medieval History at the University of Bristol. His pupils included Michael Hicks, Anne Crawford and Ralph Griffiths. He remained at Bristol until his death in 1986, when he was killed by an intruder in his own home.
Document 12: Type 30 rifle: The Type 30 rifle "Arisaka" (三十年式歩兵銃 , "Sanjū-nen-shiki hoheijū" , "year 30 type infantry firearm") was a box-fed bolt-action repeating rifle that was the standard infantry rifle of the Imperial Japanese Army from 1897 (the 30th year of the Meiji period, hence "Type 30") to 1905.
Document 13: Christopher Miner Spencer: Christopher Miner Spencer (June 20, 1833 – January 14, 1922) was an American inventor, from Manchester, Connecticut, who invented the Spencer repeating rifle, one of the earliest models of lever-action rifle, a steam powered "horseless carriage", and several other inventions. He developed the first fully automatic turret lathe, which in its small- to medium-sized form is also known as a screw machine.
Document 14: Ronald Ross: Sir Ronald Ross (13 May 1857 – 16 September 1932), was a British medical doctor who received the Nobel Prize for Physiology or Medicine in 1902 for his work on the transmission of malaria, becoming the first British Nobel laureate, and the first born outside Europe. His discovery of the malarial parasite in the gastrointestinal tract of a mosquito proved that malaria was transmitted by mosquitoes, and laid the foundation for the method of combating the disease. He was a polymath, writing a number of poems, published several novels, and composed songs. He was also an amateur artist and natural mathematician. He worked in the Indian Medical Service for 25 years. It was during his service that he made the groundbreaking medical discovery. After resigning from his service in India, he joined the faculty of Liverpool School of Tropical Medicine, and continued as Professor and Chairman of Tropical Medicine of the institute for 10 years. In 1926 he became Director-in-Chief of the Ross Institute and Hospital for Tropical Diseases, which was established in honour of his works. He remained there until his death.
Document 15: Charlton Automatic Rifle: The Charlton Automatic Rifle was a fully automatic conversion of the Lee–Enfield rifle, designed by New Zealander Philip Charlton in 1941 to act as a substitute for the Bren and Lewis gun light machine guns which were in chronically short supply at the time.
ground_truth: .303