 Requirements were issued in 1949 that the pistol had to be chambered for 9 mm Parabellum and could not exceed 7 inches in length or weigh more than 25 ounces.Candidates included Browning Hi-Power variants by Canada's Inglis and Belgium's Fabrique Nationale, and Smith & Wesson's S&W Model 39.Colt entered a modified version of their M1911 pistol that was chambered for 9 mm Parabellum, had an aluminum alloy frame, a short 4.25-inch barrel, and a 9-round magazine.