The Smith & Wesson K-38 Combat Masterpiece Revolver Model 15 is a six-shot double action revolver, with adjustable open sights, built on the medium-size "K" frame. It is chambered for the .38 Special cartridge and is fitted with a 4-inch (100 mm) barrel, though additional barrel options have been offered at various times during its production. Originally known as the K-38 Combat Masterpiece, it was renamed the Model 15 in 1957 when all Smith & Wesson revolvers were given numerical model numbers. It is a shorter barrel version of the Smith & Wesson Model 14 Target Masterpiece and essentially an adjustable-sight version of the seminal Smith & Wesson Model 10 ("Military and Police") revolver with target shooting features. The main production run of the Model 15 was from 1949 through 1999. It was discontinued for approximately a decade until 2011, when a re-tooled version was re-released under S&W's Classics Revolvers line.