High Quality Content by WIKIPEDIA articles! The .500 S&W Magnum is a fifty-caliber (12.7 mm) semi-rimmed handgun cartridge developed by Cor-Bon in partnership with the Smith & Wesson "X-Gun" engineering team for use in the Smith & Wesson Model 500 X-frame revolver and introduced in February 2003 at the SHOT show. Its primary design purpose was as a hunting handgun cartridge capable of taking all North American game species.