American infantrymen could soon get a lot more fearsome in the field: The Army has just developed a rifle that will enable soldiers to attack around corners and inside trenches. The bullet itself doesn't curve--cool as that would be. Rather, it can be programmed to explode 1-to-3 meters short of or past a given target, thus allowing its shrapnel to reach a hidden enemy. (See the diagram above.)
The XM25, invented by Alliant Techsystems , relies on a 25-millimeter round with a computer chip inside it. When a soldier sights a target, he can dial in exactly how far beyond, or how far short, of that target that he wishes the bullet to explode. Once fired, the gunsight communicates with the chip inside the bullet, providing precise distance location as it flies, and then triggering the explosion at just the right moment.
The distance-measuring mechanism is where the real ingenuity lies: The bullet also has a small magnet inside it. Since it spins as it flies (due to the rifling inside the barrel), this generates a slight AC current with every rotation. Thus, since the rifle knows exactly how far a bullet travels with every spin, it can gauge how far a bullet has traveled by monitoring its AC current. Wowzers.
It wasn't so long ago that Army critics were bemoaning the fact that it spent few resources inventing new tools for urban guerrilla wars like the ones in Afghanistan or Iraq. Looks like the Army is furiously trying to right that problem: The Army will soon begin field tests and hopes the XM25 will be in use by 2012.