Shooting people with armor-piercing bullets isn't very nice, for a number of reasons. For one, chemists went to all that trouble of creating fibers for bullet-resistant vests, and sharp-tipped projectiles make all their hard work for naught! A standard-issue nylon vest can't withstand a rifle-fired, armor-piercing bullet traveling at 850 meters per second from a range of, say, a few feet.

The U.S. Army Soldiers System Command, in Natick, Massachusetts, has applied to patent new armor that laughs off armor-piercing bullets. The armor has a three-part defense: a ceramic exterior; an aluminum layer fractured into an array of "plugs"; and a tough nylon backstop. The bullet hits the ceramic outer layer, which loosens an aluminum plug from the middle layer. The plug pops out and accelerates, nearly to bullet speed. By the time the bullet makes it through the ceramic layer-nanoseconds later-it catches up with the the aluminum, which proceeds to wrap itself around the bullet. This creates a larger surface area, essentially emasculating the bullet of its piercing ability. Aluminum-wrapped bullet hits the nylon backstop and comes safely to rest.