The Webley Mk IV is a British revolver that was introduced in 1939 and used extensively during World War II. It is chambered for the .38 S&W cartridge and features a double-action mechanism, allowing for both single and double-action firing. The revolver is known for its robust design and reliability, making it a favored sidearm among military personnel. The Webley Mk IV was part of the Webley family of revolvers, which were popular in the British armed forces. It was eventually replaced by more modern firearms, but its historical significance and distinctive design continue to be appreciated by collectors and enthusiasts of military history.