The Smith & Wesson Model 39 was the first U.S. designed double action semi-automatic pistol marketed in the United States. The German Walther P38 DA pistol impressed American ordnance personnel during World War II. The Army Ordnance Corps issued a proposal for an American equivalent to the P38. In 1949, Smith & Wesson began development of the Model 39 chambered in 9×19mm Luger and it entered the market in 1955. This is considered a first generation pistol. Since the Model 39 came out, S&W has continuously developed the design into its third generation pistols now on the market. First generation models use a 2 digit model number, second generation use 3 digits, and third generation models use 4 digits. The Model 39 was originally manufactured with an anodized aluminum frame, a curved backstrap and a blued carbon steel slide that carried the manual safety. The grip was of three pieces made of two walnut wood panels joined by a metal backstrap. It has a magazine release located at the rear of the trigger guard, similar to the M1911A1 it was designed to replace. The Model 39 was produced in limited numbers with a steel frame. This steel-frame model provided the basis for the Model 52target pistol. The Model 52 had a longer barrel and slide and was one of the few semi-automatic pistols ever chambered for the.38 Special cartridge. 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 rounds. The Model 39 used a conventional slide, barrel bushing, slide arrangement as opposed to the exposed barrel arrangement of the P38. Model 39 locking is done by a modification of the Browning P35 cam-locked breech. First generation Model 39 slides used either a long, spring steel extractor or a spring-loaded, pivoting claw extractor. Long extractors tended to be fragile and were replaced by the pivoting type. However, the long extractor proved to be more reliable than the pivoting version. The Model 39 employed many features common to the Walther P38 such as a decocking safety that disconnected the trigger and hammer. Smith & Wesson even copied the 8-round single-stack magazine as well but added a magazine catch cutout to it. The overall length of the Model 39 was 7.6 inches, the barrel is 4 inches long. The weight of the Model 39 was 1.72 pounds; this light weight is due to its aluminum frame. The Illinois State Police adopted the Model 39 in 1968, an action which helped ingratiate semi-automatic pistols with law enforcement. This publicity helped commercial sales and set the stage for the more acceptable Model 59 with its high capacity magazine at least in undercover or detective police use where the DA feature was considered by many to be superior to single-stack semi-automatics and revolvers of the time. A modified version of the Model 39 with a wider grip frame to accommodate a 14-round magazine was used by Naval Special Warfare units during the Vietnam War. It was issued to officers-in-charge of MST-2 detachments as their sidearm. SEAL Teams used either the Model 39 without modification or a modified version, the Mk 22 Mod 0, which was called the "hush puppy". The modified pistol had a suppressor with a slide lock. The Mk 22 Mod 0 had raised iron sights, to provide easier sighting over a bulky suppressor. The gun's purpose was to eliminate sentry dogs or guards without alarming the main target.
