Based on the John M. Browning-designed M1911, the Colt Commander is a single-action, semi-automatic, magazine-fed, and recoil-operated handgun. It was the first Colt handgun chambered in the 9mm Parabellum and the first American pistol with an aluminum alloy frame that was mass-produced. After World War II, the American government looked for a lighter alternative to the M1911 handgun for the officers. The 9mm Parabellum-chambered M1911 variant offered by Colt included an aluminum alloy frame, a short 4.25-inch barrel, and a 9-round magazine. Colt released their candidate into production in 1950. The Commander was produced by Colt in a number of versions and was available in both .38 Super and .45 ACP chamberings. Colt launched the all-steel "Colt Combat Commander" in 1970, with a satin nickel variant available as an option. The variant with an aluminum frame was given the new title "Lightweight Commander" to set it apart from the other two types. Other variations include models Combat Commander, Commander Gold Cup Colt, Combat Elite, and Concealed Carry Officer (a limited run of the Colt Commander in 7.65mm Luger made for export in the 70s.)