Semi-Auto, 9mm, 4" barrel 8+1, Blued. The Smith & Wesson Model 39 is a semiautomatic pistol developed for the United States Army service pistol trials of 1954. After the Army abandoned its search for a new pistol, the Model 39 went on the civilian market in 1955 and was the first of Smith & Wesson's first-generation semi-automatic pistols.