The Boys Anti-tank Rifle is a British .55 caliber anti-tank Rifle, developed shortly before the outbreak of World War II, for the purpose of allowing infantry to fight against enemy armored threats. As with all anti-tank rifles, the Boys was not necessarily meant to destroy the Tank outright, but to inflict a mobility kill by destroying the tank's tracks, or to kill the tank's crew by firing through the armor or vision slits.
Though the Boys was reasonably effective at the start of the war, the rapid pace of tank development through World War II quickly outstripped the Boys' effectiveness; worse, for anything the Boys could still damage, so too would the Browning M2, which the British had in ever more plentiful supply and which were useful in several other roles that the Boys was not. By 1943, the Boys was withdrawn from frontline service, replaced by the PIAT.
In anime, the Boys Anti-tank Rifle is famously used by Lynette Bishop in Strike Witches, as well as Karin in Blue Archive.