Just a thought... Many police departments switched from a 9mm duty weapon to a .45 calibre due to people hopped up on drugs. Im not saying the zombies in the story are crack addicts, but if a normal human can amp up on crack and meth and get shot multiple times and still function for quite a while due to the drugs keeping everything going, why can't the zombies be drugged up and able to take round after round to the chest? Of course a head shot stops ya cold, as would hitting an artery. It would be interesting with CJ's "bleed out" revelation if they could find a way to test it more. For example by cutting the femoral artery, or the carotid artery, or by a chest shot to the heart. Would definetly save on bullets in the future.