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

anti-tank Anti-tank warfare refers to the military strategies, tactics, and weapon systems designed to counter and destroy enemy armored vehicles, particularly tanks. It originated during World War I following the first deployment of tanks in 1916, and ...

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 Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. It was designed for use with the

Boys anti-tank rifle The Boys anti-tank rifle (officially Rifle, Anti-Tank, .55in, Boys, and sometimes incorrectly spelled "Boyes") is a British anti-tank rifle used during the Second World War. It was often nicknamed the "elephant gun" by its users due to its siz ...

Design

The .55 Boys is a 13.2×99mm Hotchkiss cartridge, necked up in the mid-1930s to accept a .55 caliber bullet. Since the case was left with less of a shoulder, a belt was added to ensure reliable headspacing. The .55 Boys performed poorly compared to contemporary foreign anti-tank rounds, such as the

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

7.92×94mm PatronenA smaller tungsten-cored round fired from a case about the same size as the Boys and the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

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

History

The concept of a small arms round for use against tanks began with the

13.2mm TuF round, designed during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

to counter the first British tanks. In the 1930s, the United Kingdom began designing an anti-tank rifle to address the threat posed by enemy armored vehicles in the event of a war. The gun design was initially trialed using a .50 inch bullet with a belted case. Due to insufficient armor-piercing performance, the caliber was increased to .55. Development of the .55 Boys was initiated by

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

Henry C. Boys, the assistant superintendent of design at the

Royal Small Arms Factory The Royal Small Arms Factory (RSAF), also known by the metonym ''Enfield'', was a UK government-owned rifle factory in Enfield, adjoining the Lee Navigation in the Lea Valley. Some parts were in Waltham Abbey. The factory produced British m ...

, Enfield, in 1934. Boys died before the rifle was officially adopted, and it was named in his honor. The .55 Boys round was a modified .50 BMG round necked up to accept a larger, steel-cored bullet to increase armor penetration. A belt was added to reinforce the case due to the heavy propellant charge.It is incorrectly reported that the belt was added to prevent the round from being chambered in weapons designed for the .50 BMG, though a .55-caliber cartridge could not be chambered in a .50-caliber weapon to begin with. The .55 Boys was adopted and manufactured alongside the Boys anti-tank rifle in 1937 by firms such as

Kynoch Kynoch was a manufacturer of ammunition that was later incorporated into ICI, but remained as a brand name for sporting cartridges. History The firm of Pursall and Phillips operated a 'percussion cap manufactory' at Whittall Street, in Birmin ...

throughout the

Commonwealth of Nations The Commonwealth of Nations, often referred to as the British Commonwealth or simply the Commonwealth, is an International organization, international association of member states of the Commonwealth of Nations, 56 member states, the vast majo ...

. When the United Kingdom entered World War II, the .55 Boys was soon found to be insufficient against even early war

Axis An axis (: axes) may refer to: Mathematics *A specific line (often a directed line) that plays an important role in some contexts. In particular: ** Coordinate axis of a coordinate system *** ''x''-axis, ''y''-axis, ''z''-axis, common names ...

tanks in late 1939 and 1940. However, the UK had to rely on the .55 Boys due to the lack of better infantry anti-tank weapons at the time. When the

PIAT The Projector, Infantry, Anti Tank (PIAT) Mk I was a British man-portable anti-tank weapon developed during the Second World War. The PIAT was designed in 1942 in response to the British Army's need for a more effective infantry anti-tank weapo ...

anti-tank weapon was introduced in 1943, its shaped charge proved far more effective against enemy armor than the .55 Boys. The Boys rifle was phased out of frontline service as the PIAT became the British military's primary handheld anti-tank weapon. Although not highly effective as an anti-tank weapon, the .55 Boys was used until the end of World War II by British and Commonwealth forces. It also saw use during the

Winter War The Winter War was a war between the Soviet Union and Finland. It began with a Soviet invasion of Finland on 30 November 1939, three months after the outbreak of World War II, and ended three and a half months later with the Moscow Peac ...

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 during World War II. It began with a Finnish declaration of war on 25 June 1941 and ended on 19 ...

by Finland. The Boys was issued to

Home Guard Home guard is a title given to various military organizations at various times, with the implication of an emergency or reserve force raised for local defense. The term "home guard" was first officially used in the American Civil War, starting ...

units in the UK for use against "light armored fighting vehicles... which the Home Guard are likely to have to deal with, certainly in the early stages of either an airborne or seaborne landing on our coasts." A handbook for its use noted that, in addition to the expected armor penetration at various distances and angles, 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

The first variant of the .55 Boys used a hardened-steel-core bullet with a lead sleeve, covered with a steel jacket. A ball and tracer version of this round was also developed, along with a practice round featuring an aluminum core to make it more suitable for training. It has a muzzle velocity of approximately .

Mark II

An improved loading, known as the Mark II, was introduced to enhance the round's velocity and penetration. It achieves 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 optimal angle, the Mark II round was capable of penetrating 0.91 inches (23.2 mm) of armor 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 developed in 1942. It featured a

tungsten Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...

core instead of the steel core used in previous rounds, which significantly enhanced its penetrating ability and increased its muzzle velocity from the Mark II's 884 m/s to approximately 944 m/s (3,100 ft/s). This round differed from the Mark I and II rounds due to its two-part bullet design. However, it was never officially adopted, as more effective anti-tank rounds and weapons, such as the PIAT, were being introduced. Despite its improvements, the .55 Boys, even with the enhanced APCR round, was insufficient against the heavily armored tanks of the Wehrmacht. Nevertheless, it remained effective against the more lightly armored tanks of the Imperial Japanese Army in the Asian and Pacific theaters until the end of the war.

Notes

{{DEFAULTSORT:550 Pistol and rifle cartridges Military cartridges British firearm cartridges 13.9x99mmB