A machine gun is a automatic mounted or portable firearm designed to fire rifle cartridges in rapid succession from an ammunition belt or magazine for the purpose of suppressive fire. Not all automatic firearms are machine guns. Submachine guns, assault rifles, battle rifles, pistols or cannons may be capable of automatic fire, but are not designed for sustained fire; as a class of military rapid-fire guns, machine guns are automatic weapons designed to be used as support weapons and used when attached to a mount- or fired from the ground on a bipod or tripod. Many machine guns use belt feeding and open bolt operation, features not found on rifles. In the U. S. A, a "machine gun" is a legal term for any weapon able to fire more than one shot per function of the trigger regardless of caliber, the receiver of any such weapon, any weapon convertible to such a state using normal tools, or any component or part that will modify an existing firearm such that it functions as a "machine gun" such as a drop-in auto sear.
Civilian possession of such weapons manufactured prior to 1986 is not prohibited by any federal law and not illegal in many states, but they must be registered as Title II weapons under the National Firearms Act and have a tax stamp paid. Machine guns manufactured after 1986 are prohibited by the Hughes Amendment to the Gun Owners Protection Act. Unlike semi-automatic firearms, which require one trigger pull per round fired, a machine gun is designed to fire for as long as the trigger is held down. Nowadays the term is restricted to heavy weapons, able to provide continuous or frequent bursts of automatic fire for as long as ammunition lasts. Machine guns are used against personnel and light vehicles, or to provide suppressive fire, either directly or indirectly, they are mounted on fast attack vehicles such as technicals to provide heavy mobile firepower, armored vehicles such as tanks for engaging targets too small to justify use of the primary weaponry or too fast to engage with it, on aircraft as defensive armament or for strafing ground targets, though on fighter aircraft true machine guns have been supplanted by large-caliber rotary guns.
Some machine guns have in practice sustained fire continuously for hours. Because they become hot all machine guns fire from an open bolt, to permit air cooling from the breech between bursts, they usually have either a barrel cooling system, slow-heating heavyweight barrel, or removable barrels which allow a hot barrel to be replaced. Although subdivided into "light", "medium", "heavy" or "general-purpose" the lightest machine guns tend to be larger and heavier than standard infantry arms. Medium and heavy machine guns are either mounted on a vehicle. Light machine guns are designed to provide mobile fire support to a squad and are air-cooled weapons fitted with a box magazine or drum and a bipod. Medium machine guns use full-sized rifle rounds and are designed to be used from fixed positions mounted on a tripod. Heavy machine gun is a term originating in World War I to describe heavyweight medium machine guns and persisted into World War II with Japanese Hotchkiss M1914 clones. A general-purpose machine gun is a lightweight medium machine gun which can either be used with a bipod and drum in the light machine gun role or a tripod and belt feed in the medium machine gun role.
Machine guns have simple iron sights, though the use of optics is becoming more common. A common aiming system for direct fire is to alternate solid rounds and tracer ammunition rounds, so shooters can see the trajectory and "walk" the fire into the target, direct the fire of other soldiers. Many heavy machine guns, such as the Browning M2.50 caliber machine gun, are accurate enough to engage targets at great distances. During the Vietnam War, Carlos Hathcock set the record for a long-distance shot at 7,382 ft with a.50 caliber heavy machine gun he had equipped with a telescopic sight. This led to the introduction of.50 caliber anti-materiel sniper rifles, such as the Barrett M82. Other automatic weapons are subdivided into several categories based on the size of the bullet used, whether the cartridge is fired from a closed bolt or an open bolt, whether the action used is locked or is some form of blowback. Automatic firearms using pistol-calibre ammunition are called machine pistols or submachine guns on the basis of size.
The term personal defense weapon is sometimes applied to weapons firing dedicated armor-piercing rounds which would otherwise be regarded as machine pistols or SMGs, but it is not strongly defined and has been used to describe a range of weapons from ordinary SMGs to compact assault rifles. Selective fire rifles firing a full-power rifle cartridge from a closed bolt are called automatic rifles or battle rifles, while rifles that fire an intermediate cartridge are called assault rifles. Assault rifles are a compromise between the size and weight of a pistol-calibre submachine gun and a full size battle rifle, firing intermediate cartridges and allowing semi-automatic and burst or full-automatic fire options
QF 4-inch naval gun Mk V
The QF 4 inch Mk V gun was a Royal Navy gun of World War I, adapted on HA mountings to the heavy anti-aircraft role both at sea and on land, was used as a coast defence gun. This QF gun was introduced to provide a higher rate of fire than the BL 4 inch Mk VII, it first appeared in 1914 as secondary armament on Arethusa class cruisers, was soon adapted to a high-angle anti-aircraft role. It was used on cruisers and heavier ships, although V and W class destroyers of 1917 mounted the gun. Mk V was superseded by the QF 4 inch Mk XVI as the HA gun on new warships in the 1930s, but it continued to serve on many ships such as destroyers and heavy cruisers in World War II. Early in World War I several guns were supplied by the Navy for evaluation as anti-aircraft guns for the home defence of key installations in Britain, they were mounted on static platforms and proved successful after a fixed round was developed to replace the original separate round, more followed. The AA mounting allowed elevation to 80° but loading was not possible above 62°, which slowed the maximum rate of fire.
At the Armistice a total of 24 guns were employed in 2 in France. After World War I the guns were returned to the Navy. From 1915 to 1928 several guns were mounted in forts to guard the estuary of the River Humber; the following table compares the gun's performance with the other British World War I anti-aircraft guns:- Ammunition for the original low-angle guns introduced in World War I was Separate QF i.e. the shell and cartridge were separate items, but in World War II most guns used Fixed QF ammunition i.e. a single unit. The fixed Mk V ammunition was 44.3 inches long and weighed 56 pounds, while the projectile was 31 pounds. List of anti-aircraft guns List of naval guns List of naval anti-aircraft guns Cannon 102/45 Italian copy of the QF Mk V made under license 10.5 cm SK L/45 naval gun Approximate German equivalent firing heavier shell A gun from HMNZS Tutira in front of the Devonport Naval Base, New Zealand Tony DiGiulian, British 4"/45 QF Mark V and Mark XV I. V. Hogg & L. F. Thurston, British Artillery Weapons & Ammunition 1914-1918.
London: Ian Allan, 1972. Brigadier N. W. Routledge, History of the Royal Regiment of Artillery. Anti-Aircraft Artillery, 1914-55. London: Brassey's, 1994. ISBN 1-85753-099-3 Campbell, John. Naval Weapons of World War Two. Naval Institute Press. ISBN 978-0-87021-459-2. Gun drill for 4-inch Q. F. gun mark V 1924 at State Library of Victoria
A weapon mount is an assembly used to hold a weapon a gun. Weapon mounts can be broken down into two categories: static mounts and non-static mounts. A static mount is a non-portable weapon support component either mounted directly to the ground, on a fortification, or as part of a vehicle. A gun turret protects the crew or mechanism of a weapon and at the same time lets the weapon be aimed and fired in many directions. A turret is a rotating weapon platform one that crosses the armour of whatever it is mounted on with a structure called a barbette or basket and has a protective structure on top. If it has no gunhouse it is a barbette. Turrets are used to mount machine guns, autocannons or large-calibre guns, they may be remotely controlled. A small turret, or sub-turret on a larger one, is called a cupola; the term cupola describes rotating turrets that carry no weapons but instead are sighting devices, as in the case of tank commanders. A finial is an small sub-turret or sub-sub-turret mounted on a cupola turret.
The gun is fixed on its horizontal axis and rotated by turning the turret, with trunnions on the gun used to allow it to elevate. Alternatively, in an oscillating turret the entire upper section of the turret moves to elevate and depress the gun. A casemate is an armoured structure consisting of a static primary surface incorporating a limited-traverse gun mount: this takes the form of either a gun mounted through a fixed armour plate or a mount consisting of a partial cylinder of armour "sandwiched" between plates at the top and bottom. A coaxial mount is mounted beside or above the primary weapon and thus points in the same general direction as the main armament, relying on the host weapon's ability to traverse in order to change arc; the term coaxial is something of a misnomer as the arrangement is speaking paraxial, though for ballistic purposes the axis is the same in practical terms. Nearly all main battle tanks and most infantry fighting vehicles have a coaxial machine gun mounted to fire along a parallel axis to the main gun.
Coaxial weapons are aimed by use of the main gun control. It is used to engage infantry or other "soft" targets where use of shots from the main gun would be dangerous, ineffective or wasteful; some weapons such as the M40 recoilless rifle and the Mk 153 Shoulder-Launched Multipurpose Assault Weapon have a smaller caliber spotting rifle mounted in coaxial fashion to the barrel or launch tube. These weapons fire special cartridges designed to mimic the ballistic arc of the host weapon's ammunition, using tracer or point-detonating rounds so that a gunner can determine where a shot will land in order to place fire accurately. Due to the adoption of more advanced systems such as laser rangefinders, they are used on modern weapons. A fixed mount is incapable of horizontal movement, though not vertical movement; the entire mounting must be moved in order to change direction of fire. Fixed mounts are most found on aircraft, most direct the weapon forward, along the aircraft's vector of movement, so that a pilot can aim by pointing the nose of the aircraft at the target.
Some aircraft designs used different concept of fixed mounts, as found in Schräge Musik or AC-47 Spooky. The Stridsvagn 103 is an unusual turretless main battle tank with a fixed main gun, aimed using the tank's tracks and suspension. Military aircraft often used fixed mounts called hardpoints or weapon stations to attach disposable stores such as missiles and external fuel tanks: these devices mount a standardised set of locking lugs to which many different types of armament can be affixed. Fixed traverse mounts capable of only elevation are common on larger self-propelled guns, as well being the mounting method used by all railroad guns. A pintle mount is a fixed mount that allows the gun to be traversed and/or elevated while keeping the gun in one fixed position: the mounting is either a rod on the underside of the gun that mates with a socket, or an intermediary gun cradle that mounts to the sides of the weapon's barrel or receiver. Due to the stability offered by the mount, the gun does not use a shoulder stock, with many modern examples using spade grips.
It is most found on armoured vehicles, side gun stations on WW2 and earlier bomber aircraft, the door guns of transport helicopters. Early single-shot examples referred to as swivel guns were mounted on the deck rails of naval vessels in the age of sail to deter boarders at close range. Larger guns require a heavier mounting referred to as a pedestal, larger guns a turntable platform: a pedestal mount may be directly manipulated, but larger guns require power assistance or the use of mechanical handwheels for traverse and elevation. Large mounts might include seats for the crew fixed to the gun cradle or the floor of the turntable. Unlike a turret, this type of mount has little or no armour protection at most a gunshield or splinter shield; this is a power-assisted mounting on the outside of whatever it is mounted on bolted down to the surface and with only the control wires crossing the armour. Such mountings are used on armoured fighting vehicles for anti-personnel weapons to avoid exposing a crewmen to return fire, and
The Soviet Union the Union of Soviet Socialist Republics, was a socialist state in Eurasia that existed from 1922 to 1991. Nominally a union of multiple national Soviet republics, its government and economy were 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. Other major urban centres were Leningrad, Minsk, Alma-Ata, Novosibirsk, it spanned over 10,000 kilometres east to west across 11 time zones, over 7,200 kilometres north to south. It had five climate zones: tundra, steppes 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 Tsar Nicholas II during World War I. In 1922, the Soviet Union was formed by a treaty which legalized the unification of the Russian, Transcaucasian and Byelorussian republics that had occurred from 1918. Following Lenin's death in 1924 and a brief power struggle, Joseph Stalin came to power in the mid-1920s.
Stalin committed the state's ideology to Marxism–Leninism and constructed a command economy which led to a period of rapid industrialization and collectivization. During his rule, political paranoia fermented and the Great Purge removed Stalin's opponents within and outside of the party via arbitrary arrests and persecutions of many people, resulting in at least 600,000 deaths. In 1933, a major famine struck the country. Before the start of World War II in 1939, the Soviets signed the Molotov–Ribbentrop Pact, agreeing to non-aggression with Nazi Germany, after which the USSR invaded Poland on 17 September 1939. In June 1941, Germany broke the pact and invaded the Soviet Union, opening the largest and bloodiest theatre of war in history. Soviet war casualties accounted for the highest proportion of the conflict in the effort of acquiring the upper hand over Axis forces at intense battles such as Stalingrad and Kursk; the territories overtaken by the Red Army became satellite states of the Soviet Union.
The post-war division of Europe into capitalist and communist halves would lead to increased tensions with the United States-led Western Bloc, known as the Cold War. Stalin died in 1953 and was succeeded by Nikita Khrushchev, who in 1956 denounced Stalin and began the de-Stalinization; the Cuban Missile Crisis occurred during Khrushchev's rule, among the many factors that led to his downfall in 1964. In the early 1970s, there was a brief détente of relations with the United States, but tensions resumed with the Soviet–Afghan War in 1979. In 1985, the last Soviet premier, Mikhail Gorbachev, sought to reform and liberalize the economy through his policies of glasnost and perestroika, which caused political instability. In 1989, Soviet satellite states in Eastern Europe overthrew their respective communist governments; as part of an attempt to prevent the country's dissolution due to rising nationalist and separatist movements, a referendum was held in March 1991, boycotted by some republics, that resulted in a majority of participating citizens voting in favor of preserving the union as a renewed federation.
Gorbachev's power was diminished after Russian President Boris Yeltsin's high-profile role in facing down a coup d'état attempted by Communist Party hardliners. In late 1991, Gorbachev resigned and the Supreme Soviet of the Soviet Union met and formally dissolved the Soviet Union; the remaining 12 constituent republics emerged as independent post-Soviet states, with the Russian Federation—formerly the Russian SFSR—assuming the Soviet Union's rights and obligations and being recognized as the successor state. The Soviet Union was a powerhouse of many significant technological achievements and innovations of the 20th century, including the world's first human-made satellite, the first humans in space and the first probe to land on another planet, Venus; the country had the largest standing military in the world. The Soviet Union was recognized as one of the five nuclear weapons states and possessed the largest stockpile of weapons of mass destruction, it was a founding permanent member of the United Nations Security Council as well as a member of the Organization for Security and Co-operation in Europe, the World Federation of Trade Unions and the leading member of the Council for Mutual Economic Assistance and the Warsaw Pact.
The word "Soviet" is derived from a Russian word сове́т meaning council, advice, harmony and all deriving from the proto-Slavic verbal stem of vět-iti, related to Slavic věst, English "wise", the root in "ad-vis-or", or the Dutch weten. The word sovietnik means "councillor". A number of organizations in Russian history were called "council". For example, in the Russian Empire the State Council, which functioned from 1810 to 1917, was referred to as a Council of Ministers after the revolt of 1905. During the Georgian Affair, Vladimir Lenin envisioned an expression of Great Russian ethnic chauvinism by Joseph Stalin and his supporters, calling for these nation-states to join Russia as semi-independent parts of a greater union, which he named as the Union of Soviet Republics of Europe and Asia. Stalin resisted the proposal, but accepted it, although with Lenin's agreement changed the name of the newly proposed sta
QF 4.7-inch Mk IX & XII naval gun
The 4.7 inch QF Mark IX and Mark XII were 45-calibre, 4.7-inch naval guns which armed the majority of Royal Navy and Commonwealth destroyers in World War II, were exported to many countries after World War II as the destroyers they were mounted on were sold off. These guns succeeded the similar World War I-era BL 4.7 inch gun, changing the cartridges from BL silk bags to separate QF in brass cases and a new horizontal sliding-block breech mechanism. Mark IX was deployed in single mountings CP Mk XIV on the A-class destroyers of 1930 and on most subsequent destroyer classes up to and including the R class of 1942; the almost-identical Mk XII gun was deployed in twin mountings CP Mk XIX on the Tribal-class destroyers of 1936 and J, K and N classes of 1938. This mounting limited the maximum elevation to 40 degrees, but all twin CP Mk XIX were dual-purpose mountings and were equipped with Fuze Setting Pedestals or Mk V Fuze Setting Trays, to allow the mountings to be fired against aircraft while being controlled by the Fuze Keeping Clock fire control computer.
Typical maximum rate of fire was twelve rounds per gun, per minute. During gunnery trials in 1930, HMS Basilisk' was able to fire "...five rounds in 17 seconds." The Mk XII gun fired a 50 lb shell and used a separate cartridge, with both shell and cartridge being loaded via a loading tray, with power ramming and traverse. The maximum range at 40 degrees elevation was 16,970 yards fired at the new gun muzzle velocity of 2,650 fps; the 40-degree elevation was justified on the grounds that destroyers would be screening the battle-fleet during aerial attack, 40 degrees elevation was adequate to engage aircraft that were concentrating their attack on other ships. Admiral Sir Philip Vian describes the use of Tribal-class destroyer mounted Mk XII guns against aircraft during the campaign in Norwegian waters, from April to June 1940: "It became clear at once that in an attack from the air in narrow waters flanked by mountains, the cards were held by the aircraft. There was too little sea-room for full freedom of manoeuvre, the aircraft's approach was screened by the rock walls.
As as not, when they did come into view it was at such an angle that our 4.7-inch guns, whose maximum elevation was only forty degrees, could not reach them... Aandalsnes is approached through the Romsdal Fiord, lies forty miles from the entrance, off which we arrived on the 24th April; the daylight passage of the convoy and escort through this waterway, speed five knots, on a steady course and with mountains rising steeply either side, presented an alluring invitation to enemy aircraft. Junkers attacks persisted to the end, but the fire of the destroyers, although limited to an elevation of forty degrees, was enough to keep the enemy just too high for their standard of marksmanship. Not a ship received a direct hit, though some were damaged by the splinters from near misses." The S class, introduced the CP single Mark XXII mounting for the QF Mark XII 4.7 in gun. This new mounting had a shield with a raked front, to allow increased elevation, contrasting noticeably with the vertical front of the previous CP Mark XVIII, differentiated the S class onwards from their immediate predecessors.
Savage was the exception in this respect, being fitted with 4.5 inch calibre. The 4.7 inch calibre was superseded by the 4.5 inch calibre on the Z-class destroyers in 1943. The new 4.5 inch guns all had 55-degree elevation mounts and fired a shell heavier than that of 4.7-inch Mk IX and XII guns, although lighter than that fired by the 4.7 inch Mk XI gun. 12.7 cm SK C/34 naval gun: equivalent German destroyer gun, firing heavier shell 5"/38 caliber gun: approximate US equivalent, firing a heavier shell Campbell, John. Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-459-4. Hodges, Peter. Destroyer Weapons of World War 2. London: Conway Maritime Press. ISBN 0-87021-929-4. March, Edgar J.. British Destroyers: A History of Development, 1892-1953. London: Seeley Service. OCLC 164893555. Illustration of a 4.7 inch single mount Tony DiGiulian, Britain 4.7"/45 QF Mark IX 4.7"/45 QF Mark XII
4.5-inch Mark 8 naval gun
The 4.5 inch Mark 8 is a British naval gun system which equips the Royal Navy's destroyers and frigates, some British destroyers and frigates sold to other countries. The 4.5 inch gun has been the standard medium-gun calibre of the Royal Navy for use against surface and shore targets since 1938. The current 55-calibre Mark 8 gun replaced the World War II era 45-calibre QF 4.5-inch Mk I – V naval guns. Like all British 4.5 inch naval guns, it has a calibre of 4.45 inches. A new type of 4.5 inch gun with a longer 55-calibre barrel, it was designed in the 1960s for the Royal Navy's new classes of frigates and destroyers. The new weapon, built by Vickers Ltd Armament Division, was developed by the Royal Armament Research and Development Establishment using the Ordnance, QF 105 mm L13 of the Abbot self-propelled gun as a starting point; the outer shell of the gunhouse is built from glass-reinforced plastic. The new weapon emphasised reliability and rapid response to fire first round from shutdown state over a high rate of fire, allowing a switch to a lighter, single barrel mounting and ammunition of a one-piece design.
The gun system has a combination of electrical and hydraulic components and the full system penetrates up to three deck levels below the weather deck. The weapon can be operated by a smaller crew than its predecessors. With no personnel in the gunhouse, loading is supported by personnel in the gunbay to load the feed ring and in the deep-magazine to pass ammunition to the gunbay; the captain of the gun in the control room ensures continued weapon readiness and the gun controller in the operations room aims and fires the weapon. The gun has a rate of fire of a range of 12 nm; the first recipient of the new gun and mount, the Mark 8, was the Iranian frigate Zaal in 1971. The gun entered Royal Navy service in 1973 on the new destroyer Bristol; these guns proved to be less reliable than the older 4.5 inch Mark V gun during the Falklands War, being forced to cease fire on several occasions due to faults. The first major modification to the mounting, the Mod 1, was developed in 1998 in two tranches.
This particular gun has been nicknamed the "Kryten gun" by members of Royal Navy, after the odd shaped head of a robot from the British Sci-fi comedy series Red Dwarf. Babcock upgraded 13 guns to Mod 1 standard between 2005 and 2012; the Ministry of Defence investigated a proposal from BAE Systems to adapt the 4.5 inch system to accept the heavier calibre 155 mm gun barrel and breech from the AS-90 self-propelled gun. This "155mm Third Generation Maritime Fire Support" would introduce a common gun calibre for the British Army and Royal Navy, helping with ammunition logistics, encouraging joint Army-Navy development of extended range and precision guided shells. A £4m contract was awarded to develop a prototype, firing trials were scheduled for 2009 with delivery in 2014, but the project was cancelled in the cuts implemented following the 2010 Strategic Defence and Security Review. Although the Mk 8 was fitted to the Type 45 destroyer, on the Type 26 Global Combat Ship it will be supplanted by the BAE 5-inch Mk 45 naval gun.
Royal Navy Type 45 guided missile destroyer Type 23 frigate Type 22 frigate Type 21 frigate Type 42 guided missile destroyer Type 82 destroyer guided missile destroyer Chilean Navy Type 23 frigate Argentine Navy ARA Hércules former Type 42, converted into a multi-purpose transport ship ARA Santísima Trinidad Type 42 guided missile destroyer Brazilian Navy Niteroi class Inhauma class Islamic Republic of Iran Navy Alvand class Libyan Navy Dat Assawari Royal Thai Navy HTMS Makut Rajakumarn Royal Malaysian Navy KD Rahmat QF 4.5-inch Mk I – V naval gun – British predecessor Advanced Gun System – BAE's new 155 mm long-range gun system for the US Navy's Zumwalt class destroyers 5"/54 caliber Mark 45 gun: contemporary standard naval gun for US ships AK-130: contemporary 130 mm twin standard naval gun mounting for Russian ships French 100 mm naval gun: contemporary standard naval gun for French ships Otobreda 127/54 Compact and Otobreda 127/64: contemporary 127 mm naval gun from Italian manufacturer Oto Melara Tony DiGiulian, British 4.5"/55 Mark 8 Mod 0 114 mm/55 Mark 8 Mod 1
Glossary of British ordnance terms
This article explains terms used for the British Armed Forces' ordnance and ammunition. The terms may have different meanings in the military of other countries. Between decks: applies to a naval gun mounting in which part of the rotating mass is below the deck, part of it is above the deck; this allows for a lower profile of turret, meaning that turrets need not be superfiring The term BL, in its general sense, stood for breech loading, contrasted with muzzle loading. The shell was loaded via the breech followed by the propellant charge, the breech mechanism was closed to seal the chamber. Breech loading, in its formal British ordnance sense, served to identify the gun as the type of rifled breechloading gun for which the powder charge was loaded in a silk or cloth bag and the breech mechanism was responsible for "obturation" i.e. sealing the chamber to prevent escape of the propellant gases. The term BL was first used to refer to the Armstrong breechloaders, introduced in 1859. Following the discontinuation of Armstrong breechloaders and the period of British rifled muzzle-loaders, British breechloaders were re-introduced in 1880.
At this point the term RBL was retrospectively introduced to refer to the Armstrong breechloaders, which had a different breech mechanism, since the term BL has applied to the type of breechloader introduced from 1880 onwards using interrupted-screw breeches. Early British Elswick breechloaders in the 1880s used a steel "cup" obturation method; this was superseded in guns designed by the Royal Gun Factory by the French de Bange method, the basic principle of, still in use today. In British service this became a Crossley pad with an interrupted thread screw block e.g. a Welin screw. The shell was loaded via the breech, followed by the propellant charge in a cloth bag. A single-use "vent sealing tube", a type of primer not dissimilar in appearance to a blank rifle round, was inserted into the breech for firing the gun. While the term "BL" contrasted with "ML", or "muzzleloader" guns, after muzzleloaders were discontinued, the term came to distinguish between traditional, non-obturating guns with fabric propellant bags and separately loaded shells, quick-firing QF guns which used self-sealing brass cartridge cases, which had the propellant and projectile fixed together as a unit for faster handling and loading.
For instance, Britain before World War I had both BL 6 inch guns. Both were "breech loading" in the general sense, but in the formal nomenclature it separated 6-inch guns with breeches designed for charges in brass cartridge cases from those designed for cloth bag charges. Shells designed for one type were not suitable for use in the other type; this presented difficulties for BL guns at high angles. A special cartridge was developed for BL 9.2 inch guns on HA mountings, with provision for a wooden stick to be inserted through the centre to prevent the shell slipping back on elevation. Although fixed ammunition allows for a rapid rate of fire in small to medium guns, BL is a better choice for heavy calibre guns. Using fabric allows for the charge to be broken into small handled units, while it would be difficult to design a system by which multiple small metallic-cased charged were loaded and fired at the same time. Using multiple small fabric bags allows the gunners to use a reduced charge if need be.
The term "BLC" stood for "BL converted" and referred to a breech and breech mechanism modified from an early long-screw three- or four-motion to modern short-screw single-motion. An example is the conversion of the BL 15 pounder to BLC 15 pounder. Calibre radius head: the radius of a circle with the curve of the shell's nose on its circumference, expressed in terms of the shell's calibre; the longer and more pointed the shell's nose, the higher the C. R. H. Typical C. R. H. for British shells leading up to World War I was two: e.g. the curve of the nose of a two C. R. H. Six-inch shell was equivalent to the curve of a circle with a radius of 12 inches. Shells of four C. R. H. were soon developed in World War I, identified by an A following the shell mark number, B for six, so on. For modern streamlined shells post-World War I, two numbers were necessary to more denote a shell's C. R. H. Characteristics. For instance, the World War I 6 inch 26 cwt howitzer shell was two C. R. H; the World War II Mk 2D shell was described as "5/10 C.
R. H.". "Cartridge" in British ammunition terminology refers to the physical object containing the propellant that a gunner loads: For small arms and fixed QF artillery ammunition e.g. the.303 or 18-pounder this denoted the complete round, i.e. cartridge case, percussion cap or primer, propellant charge and projectile. In this use it is synonymous with "round". For separate QF artillery, cartridge referred to the cartridge case, its primer, propellant charge, the disposable lid and fastener of the case. In BL artillery terminology, cartridge referred to the propellant unit only - there was no case. British cartridges up to 1892 contained gunpowder, thereafter sticks of cordite bound up together with an igniter pad if necessary, in a cloth