The Model 640 Centennial is a fully hammerless double-action-only J-frame in stainless steel chambered for .357 Magnum. It combines the snag-free Centennial profile with genuine magnum capability in an all-stainless package. Type: Revolver Action: DAO Caliber: .357 Mag Capacity: 5 Year introduced: 1990, USA Weight: 23 oz Overall length: 6.6" Status: Active Intended use: Carry, Backup