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From the perspective of pure Newtonian physics, the 10mm Auto cartridge is the ballistic equivalent of about one and one half 9mm Parabellum rounds. It’s roughly on par with the .357 Magnum. Devised by Jeff Cooper back in the 1980s to pack magnum revolver power into an autoloading pistol, the 10mm Auto throws a 180-gr. .40-caliber bullet at around 1,300 feet per second. The end result will reliably drop a feral hog or whitetail deer. It will also put the holy smackdown on two-legged predators of all shapes, sizes and flavors.

The 10mm Auto case is 25.2mm long. The proven .40 S&W round launches the same bullet, yet its case length is only 21.6mm. Despite the prodigious horsepower of the 10mm Auto, the grip circumference of this new XD(M) measures out to a single millimeter larger than the 9mm GLOCK.

In the field of social ballistics, big bullets have in the past always reliably equaled big ornery guns. Springfield Armory, however, has somehow warped the natural laws governing the universe to contrive a high-capacity handgun throwing a massive game-dropping round yet occupies no more space than does your typical 9mm service pistol.

In my left hand I currently hold my favorite tricked-out 9mm GLOCK 17. In my right I grasp a new Springfield Armory XD(M) 10mm. The XD(M) is maybe a quarter inch longer, but they’re otherwise about the same size.