The Model 40 Centennial was the first fully hammerless double-action-only revolver S&W produced, introduced as a commemorative design in 1952. The completely concealed hammer made it the prototype for all subsequent Centennial J-frames including the 442 and 642. Type: Revolver Action: DAO Caliber: .38 Spl Capacity: 5 Year introduced: 1952, USA Weight: 19.5 oz Overall length: 6.5" Status: Discontinued Intended use: Carry, Backup