Final Mission (1984)

Vince Deacon, a higly decorated Vietnam War veteran, serves as a SWAT team captain for LAPD. When his family gets attacked by thugs and he kills one of them in self defense he's being suspended by his boss. Deacon and his family decide to spend the weekend camping at a lake to forget about everything but an explosion on their boat kills both his wife and kid. He finds out that Slater, a war buddy-turned-traitor is responsible for the murders. Deacon tracks him down to a small town in the mountains and gets his revenge only to be haunted by a redneck sheriff who happens to be Slater's brother. Not even his former commander, Col. Cain, or the National Guard can stop him now...