Smith & Wesson Model 66, Double/Single Action, Metal Frame Revolver, K-Frame, 357 Magnum, 4.25 Barrel, Stainless Steel, Matte Finish, Rubber Grips, Adjustable Sights, 6 Rounds 162662 Since its introduction in 1899, the K-Frame has been a favorite for military and police professionals as well as target shooters and enthusiasts. The Model 66 features Ball-Detent Lock-Up, Full Top Strap and Barrel Serration and Matte Stainless finish.