The 10mm Auto (10x25mm), which I have carried on duty and used in competition, has become one of my favorite self-defense and pistol hunting calibers. Loaded to the max, it’s quite powerful and was designed to deliver .41 Magnum ballistics in a semiauto handgun. But the .41 Magnum revolver round remains energy boss at a maximum of 1,135 foot-pounds of muzzle energy (me), while the ten has made it to 1,015 foot-pounds with lighter projectiles at 2,420 feet-per-second (fps).