The 10 mm is, in our humble opinion, the most underrated and under appreciated round. Obviously, we are not the only ones who feel this way, because the 10 mm has its own cult following. It was designed to be a medium-velocity pistol cartridge with better external ballistics (i.e., flatter trajectory, greater range) than the .45 ACP and capable of greater stopping power than the 9×19mm Parabellum. Due to undesirable recoil, it was lacking in popularity. Had it not been for Colt’s Patent Fire Arms Manufacturing Company making the unexpected decision in 1987 to bring out their Delta Elite pistol (a 10 mm Auto version of the M 1911) and later, the FBI’s adoption of the caliber in 1989, the cartridge might have sunk into obsolescence, becoming an obscure footnote in firearms history. Firearms chambered in this round include the Colt Delta Elite, Glock 20, Glock 29 and the Dan Wesson M1911.