COLLINSVILLE, Va.— Andy Parker’s resolve to fight for gun control formed in the hours after his daughter was shot and killed on live television. In his first interviews after the tragedy, he briefly mentioned the issue as he eulogized Alison. By Friday, he was pledging a full-scale fight for tougher gun laws on national TV. ”This will be my mission,” he told reporters. While his articulate Southern voice renews a push for gun restrictions, winning such measures has proved nearly impossible in the U.S., even after other high-profile tragedies garnered sympathy across the country and elicited similar pledges of activism from victim’s relatives. And Parker is starting his battle in unforgiving territory.