The Rifle, Anti-Tank, .55in, Boys commonly known as the "Boys (or, often and incorrectly,"Boyes") Anti-tank Rifle" was a British anti-tank rifle. There were three main versions of the Boys, an early model (Mark I) which had a circular muzzle brake and T shaped bipod, a later model (Mk II) that had a square muzzle brake and a V shaped bipod, and a third model made for airborne forces with a 30-inch (762 mm) barrel and no muzzle brake. There were also different cartridges, with a later version offering better penetration.
Design and development
The eponymous creator of this firearm was Captain H C Boys (the Assistant Superintendent of Design) who was a member of the British Small Arms Committee and a designer at the Royal Small Arms Factory, Enfield. It was initially called Stanchion but was renamed after Captain Boys as a mark of respect when he died a few days before the rifle was approved for service in November 1937.
A bolt action rifle fed from a five-shot magazine, the weapon was large and heavy with a bipod at the front and a separate grip below the padded butt. In order to combat the recoil caused by the large 0.55 inch (13.9 mm) round, the barrel was mounted on a slide, and a shock absorber was fitted to the bipod along with a muzzle brake on the barrel. The Boys had been designed with numerous small narrow-slotted screws of soft steel set very tight into the body of the weapon, and its repair and maintenance proved a nightmare for British ordnance repair crews.
The cartridge was an adaption of the Browning 0.5 inch, with a belt added firing a 47.6 gram bullet.
At its introduction, the weapon was effective on light armour (16 mm thick) at 100 yards (91 m). There were two main service loads used during the Second World War, the W Mark 1 (60 g AP at 747 m/s) and the W Mark 2 ammunition (47.6 g AP projectile at 884 m/s). The W Mark 1 could penetrate approximately 16 mm of armour at 100 yards, about the thickness used on the frontal armour of a half-track or armoured car, or the side or rear armour of a light tank. Later in the conflict, a more effective round was developed, the W Mark 2, which fired a tungsten-cored projectile at 945 m/s. The W Mark 2 was able to penetrate up to 3/4 inch (19 mm) of armour at 100 yards (~91 m), with the plate inclined at 70° from the horizontal (i.e. 20 degrees from the direct line angle of fire), the effective thickness being ~21.5 mm at 0°. Its effective range against unarmoured targets (e.g. infantry), was much further. Despite its recoil slide and cushioned buttpad, the felt recoil of the weapon (along with noise and muzzle blast) was terrific, frequently causing neck strains and bruised shoulders. Consequently, the Boys was almost never fired as a free weapon (i.e. not affixed to a support) except in emergencies.