The .55 Boys (13.9×99mmB in metric) is an

anti-tank Anti-tank warfare originated from the need to develop technology and tactics to destroy tanks during World War I. Since the Triple Entente deployed the first tanks in 1916, the German Empire developed the first anti-tank weapons. The first ...

cartridge used by the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

. It was designed for use with the Boys Anti-Tank Rifle.

Design

The .55 Boys is a 13.2×99mm Hotchkiss cartridge necked up to accept a .55 caliber bullet in mid-1930s. Since the shoulder of the case was narrowed, a belt was added to ensure reliably correct headspace. It performed poorly when compared to contemporary foreign anti-tank rounds, such as the German 7.92×94mm PatronenA smaller tungsten cored round fired from a case about the same size as the Boys and the

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

14.5×114mm rounds and, as a result, it was quickly deemed obsolete.''Ammo Encyclopedia'', Second Edition by Michael Bussard, p. 563

History

The concept of a small arm round for use against

tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful ...

s began with the German 13.2mm TuF round, designed during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

for use against the first British tanks. In the 1930s, the United Kingdom began designing an anti-tank rifle to counter enemy armoured vehicles in the event of a war. Initially the gun design was trialled using .50 inch bullet with a belted case due to lack of armour-piercing performance the calibre was increased to .55 Development on what is known as the .55 Boys was started by

Captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...

Henry C. Boys, the Assistant Superintendent of Design at the Royal Small Arms Factory, Enfield in 1934. Boys died before the rifle was officially adopted and it was named after him. The .55 Boys round was a modified .50 BMG round necked up to accept a larger, steel-cored bullet in order to increase its armour penetration. A belt was added to reinforce the case with the heavy propellant charge.It is incorrectly reported that the belt was added to ensure the round could not be chambered in weapons designed for the .50 BMG. though .55-calibre cartage could not be chambered in a .50-calibre weapon to begin with. The .55 Boys was adopted and manufactured alongside the Boys Anti-Tank Rifle in 1937 throughout the

Commonwealth of Nations The Commonwealth of Nations, simply referred to as the Commonwealth, is a political association of 56 member states, the vast majority of which are former territories of the British Empire. The chief institutions of the organisation are the ...

by firms such as Kynoch. When the United Kingdom entered World War II, the .55 Boys round was soon found to be insufficient against even early war Axis tanks in late 1939 and 1940. However, the United Kingdom had to rely on the .55 Boys round because no better infantry anti-tank weapons were available. When the PIAT anti-tank weapon was introduced in 1943, the shaped charge it fired was far more effective against enemy armour than the .55 Boys round. The Boys rifle was phased out of service on the frontline as the PIAT became the British military's primary handheld anti-tank weapon. Although not effective as an anti-tank weapon, the .55 Boys was used until the end of World War II by British and Commonwealth countries. It also saw use during the

Winter War The Winter War,, sv, Vinterkriget, rus, Зи́мняя война́, r=Zimnyaya voyna. The names Soviet–Finnish War 1939–1940 (russian: link=no, Сове́тско-финская война́ 1939–1940) and Soviet–Finland War 1 ...

and

Continuation War The Continuation War, also known as the Second Soviet-Finnish War, was a conflict fought by Finland and Nazi Germany against the Soviet Union from 1941 to 1944, as part of World War II.; sv, fortsättningskriget; german: Fortsetzungskrieg. A ...

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

. The Boys was issued to Home Guard units in the UK for use against "light armoured fighting vehicles...which the Home Guard are likely to have to deal with, certainly in the early stages of either an air-borne or sea-borne landing on our coasts." A handbook for its use noted that as well as the expected penetration of armour at various distances and angles that it would penetrate 14 inches of brick wall and 10 inches of sandbags. ''Boys Anti-tank Rifle - Mark 1'' 1944. Gale and Polden Ltd np7 By the conclusion of World War II, the .55 Boys was no longer used in any major capacity.

Variants

The .55 Boys round went through two major variants in its lifetime, along with an experimental variant that was never adopted by the United Kingdom.

Mark I

This is the first variant of the .55 Boys. It uses a . hardened steel core bullet with a lead sleeve, which is covered with a steel jacket. A ball and tracer version of this round was also created along with a practice round using an aluminum core in order to be more feasible for training. It has a muzzle velocity of roughly .

Mark II

An improved loading named the Mark II was released in order to increase the round's velocity and its penetration. It generates a muzzle velocity of approximately 884 m/s (2,899.5 ft/s).Bad Boys The British Rifle, Anti-Tank, .55 In, Boys
/ref> At an ideal angle, the Mark 2 round was able to pierce 0.91 inches (23.2 mm) of armour at , 0.82 inches (20.9 mm) at and 0.74 inches (18.8 mm) at .

APCR tungsten round

An experimental armour-piercing composite rigid (APCR) .55 Boys round was designed in 1942. It used a

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first i ...

core instead of a steel core, which greatly increased its penetrating ability and gave a boost to its muzzle velocity from the Mark II's 884 m/s to approximately 944 m/s (3100 ft/s). It differs from the Mark I and II rounds because of its two-part bullet. This model was never officially adopted because far better anti-tank rounds and weapons, such as the PIAT, were entering service at the time. The .55 Boys, even with a greatly improved bullet, was simply too weak to defeat the tanks being fielded by the Axis powers.

Notes

{{DEFAULTSORT:550 Pistol and rifle cartridges Military cartridges British firearm cartridges