The idea of necking the 45 ACP down to 10mm is not a new idea. During the early 90’s, long before the development of the 40 SUPER, Charles Petty who was a respected gun-writer developed the 10mm Centaur together with Ray Herriott who was the designer and Richard Beebe of Redding Reloading made dies for it. The Centaur is based on the 45 ACP necked to .40cal (10mm) using 10mm Auto dies.