Boys Anti-Tank Rifle in .55 Boys with a 36-inch barrel. A British bolt-action anti-tank rifle designed by Captain Boys and produced by BSA, intended to defeat early tank armor during World War II. Type: Rifle Action: Bolt-Action Caliber: .55 Boys Capacity: 5 Year introduced: 1937, UK Weight: 392 oz Overall length: 63.5" Status: Discontinued Military use: Yes Intended use: Anti-Tank, Military