Everybody knows the only way to stop a Zombie is to blow his head off! Body armor on a Zombie just slows him down more.
BTW, ever watch a TV show or movie where someone actually has a gun then shoots the Vampire/Zombie/Werewolf/whatever in the chest to no effect? Am I the only one who yells "HEAD SHOT, YOU IDIOT!" at the screen? It may not "kill" them, but I gotta believe even the baddest monster out there is gonna be slowed down a bit with a large portion of their brain missing or chopped into hamburger.