I read he shot himself by accident and was discharged-
http://www.wnd.com/2004/08/26004/
“While Kerry claims the injury came from shrapnel from an underwater mine, Larry Thurlow, an officer on shore with Kerry that day, insists the wound was the result of Kerry’s decision to throw a concussion grenade into a rice pile. The “shrapnel,” he says, was actually rice pellets.”