We often hear about “bullet proof” vests. TV/movie good guys shot while wearing one immediately fall to the ground, breathless and momentarily incapacitated, even though the bullet did not penetrate the vest. Dramatic, but mostly nonsensical. There is no such thing as a “bullet proof” vest, merely vests designed to be bullet resistant, capable, depending on design, of stopping some, but not all, cartridges. The vests worn by these US troops, for example, are commonly rated to stop the usual rifle caliber cartridges of known enemies. However, they are heavy, hot and somewhat restrict movement. Graphic: Pfc. Ty Correll provides...