Anti-tank guns deployed during World War II were often manned by specialist infantry rather than artillery crews, and issued to light infantry units accordingly.[1] The anti-tank guns of the 1930s were of small caliber; nearly all major armies possessing them used 37mm ammunition, except for the British Army, which had developed the 40mm Ordnance QF 2-pounder.[2] As World War II progressed, the appearance of heavier tanks rendered these weapons obsolete and anti-tank guns likewise began firing larger and more effective armor-piercing shot.[3] The development of the compact hollow charge projectile permanently altered anti-tank warfare, since this type of ammunition did not depend on a high muzzle velocity and could be fired from low-recoil, man-portable light weapons, such as the Panzerfaust and the American series of recoilless rifles.[3]