The QF 4.5 inch gun has been the standard medium-calibre naval gun used by the Royal Navy as a medium-range weapon capable of use against surface, aircraft and shore bombardment targets since 1938. This article covers the early 45-calibre family of guns up to the 1970s. For the later unrelated 55-calibre Royal Navy gun, see 4.5 inch Mark 8 naval gun. Like all British nominally 4.5 inch naval guns, the QF Mk I has an actual calibre of 4.45 inches (113 mm).
HMAS Sydney was a Chatham-class light cruiser of the Royal Australian Navy (RAN). Laid down in 1911 and launched in 1912, the cruiser was commissioned into the RAN in 1913.
The BL 6-inch gun Mark VII was a British naval gun dating from 1899, which was mounted on a heavy travelling carriage in 1915 for British Army service to become one of the main heavy field guns in the First World War, and also served as one of the main coast defence guns throughout the British Empire until the 1950s.
The QF 4.7-inch Gun Mks I, II, III, and IV were a family of British quick-firing 4.724-inch (120 mm) naval and coast defence guns of the late 1880s and 1890s that served with the navies of various countries. They were also mounted on various wheeled carriages to provide the British Army with a long range gun. They all had a barrel of 40 calibres length.
The QF 4 inch Mk V gun was a Royal Navy gun of World War I which was adapted on HA mountings to the heavy anti-aircraft role both at sea and on land, and was also used as a coast defence gun.
The BL 9.2-inch Mk IX and Mk X guns were British breech loading 9.2-inch (234 mm) guns of 46.7 calibre, in service from 1899 to the 1950s as naval and coast defence guns. They had possibly the longest, most varied and successful service history of any British heavy ordnance.
The BL 9.2-inch Mk I–VII guns were a family of early British heavy breechloading naval and coast defence guns in service from 1881 to the end of World War I. They were originally designed to use the old gunpowder propellants.
The BL 6-inch gun Marks II, III, IV and VI were the second and subsequent generations of British 6-inch rifled breechloading naval guns, designed by the Royal Gun Factory in the 1880s following the first 6-inch breechloader, the relatively unsuccessful BL 6-inch 80-pounder gun designed by Elswick Ordnance. They were originally designed to use the old gunpowder propellants but from the mid-1890s onwards were adapted to use the new cordite propellant. They were superseded on new warships by the QF 6-inch gun from 1891.
The BL 10 inch guns Mks I, II, III, IV were British rifled breechloading 32-calibre naval and coast defence guns in service from 1885.
The QF 4-inch gun Mk IV was the main gun on most Royal Navy and British Empire destroyers in World War I. It was introduced in 1911 as a faster-loading light gun successor to the BL 4 inch Mk VIII gun. Of the 1,141 produced, 939 were still available in 1939. Mk XII and Mk XXII variants armed many British interwar and World War II submarines.
The BL 4-inch gun Mk VII was a British high-velocity naval gun introduced in 1908 as an anti-torpedo boat gun in large ships, and in the main armament of smaller ships. Of the 600 produced, 482 were still available in 1939 for use as coastal artillery and as a defensive weapon on Defensively Equipped Merchant Ships (DEMS) during the Second World War.
The BL 5-inch guns Mk I – Mk V were early British 5-inch rifled breechloading naval guns after it switched from rifled muzzle-loaders in the late 1870s. They were originally designed to use the old gunpowder propellants. The 5-inch calibre was soon discontinued in favour of QF 4.7-inch.
The BL 6-inch Mark XII naval gun was a British 45 calibre naval gun which was mounted as primary armament on light cruisers and secondary armament on dreadnought battleships commissioned in the period 1914–1926, and remained in service on many warships until the end of World War II.
The BL 9.2-inch Mark XI gun was a British 50 calibre high-velocity naval gun which was mounted as primary armament on armoured cruisers and secondary armament on pre-dreadnought battleships.
The BL 7.5-inch Mk II–Mk V guns were a variety of 50-calibre naval guns used by Britain in World War I. They all had similar performance and fired the same shells.
The BL 8 inch gun Mark VIII was the main battery gun used on the Royal Navy's County-class cruisers, in compliance with the Washington Naval Treaty of 1922. This treaty allowed ships of not more than 10,000 tons standard displacement and with guns no larger than 8 inches (203 mm) to be excluded from total tonnage limitations on a nation's capital ships. The 10,000 ton limit was a major factor in design decisions such as turrets and gun mountings. A similar gun formed the main battery of Spanish Canarias-class cruisers. In 1930, the Royal Navy adopted the BL 6 inch Mk XXIII naval gun as the standard cruiser main battery in preference to this 8-inch gun.
The 50 calibre BL 6 inch gun Mark XXIII was the main battery gun used on the Royal Navy and British Commonwealth's conventional (non-anti-aircraft) light cruisers built from 1930 through the Second World War, and passed into service with several other navies when ships were disposed of after the end of the War.
The 15 cm/50 41st Year Type gun was a naval gun used by the Imperial Japanese Navy before and during World War II. It had a 152 millimetres (6.0 in) bore with a length of 7.6 metres (25 ft) and fired 45.4 kilograms (100 lb) shell for a distance of 18,000 metres (20,000 yd) or 21,000 metres (23,000 yd). The gun was first used in single casemates on the Kongō-class battlecruisers and Fusō-class battleships and later in the Agano-class light cruisers in twin mountings.
The BL 6-inch Mk XXII gun was a British high-velocity 6-inch 50-calibre wire-wound naval guns deployed on the Nelson-class battleships from the 1920s to 1945.
