Smith & Wesson "N" to the largest .44 Magnum type frame. In 2003, the even larger "X" frame was introduced for the .500 S&W Magnum. Most Smith & Wesson revolvers have been equipped with an internal locking mechanism since the acquisition by Saf-T-Hammer. The mechanism is relatively unobtrusive, is activated with a special key, and renders the firearm inoperable. While the lock can simply be left disengaged, most gun enthusiasts prefer "pre-lock" guns. In 1953 the U.S. Army was looking for a pistol to replace the Colt 1911A1. To obtain a bid from the U.S. Government, Smith & Wesson began working on a
Smith & Wesson Model 39 wadcutter bullets only). The shape of the rimmed cartridge limited the magazine capacity to five rounds. A further variant, the Model 952, in 9mm Luger, is still produced in limited quantities by Smith & Wesson's Performance Center. The Model 52 was discontinued in 1992 when the machinery to manufacture the pistol broke down and it was deemed too costly to replace. The Model 39 was the basis for the later Smith & Wesson Model 59, retaining the original 9mm Parabellum caliber, but incorporating a wider aluminum frame with a straight backstrap to accommodate a double-column magazine that could hold 14