Cimarron Thunderball, Single Action Only, 9MM, 3.5 Barrel, Steel, Nickel Finish, Birdshead Walnut Grips, Fixed Sights, 6 Rounds PP9MMNTH The Thunderball is a single action 9MM revolver with a 3.5" barrel that features a nickel finish and birdshead walnut grips. With a front blade sight and a rear notched frame, the pistolero will be you next favorite single action revolver in your collection.