Barbarosa (movie, 1982)

Karl Westover, an inexperienced farm boy, runs away after unintentionally killing a neighbor, whose family pursues him for vengeance. He meets Barbarosa, a gunman of near-mythical proportions, who is himself in danger from his father-in-law Don Braulio, a wealthy Mexican rancher. Don Braulio wants Barbarosa dead for marrying his daughter against the father's will. Barbarosa reluctantly takes the clumsy Karl on as a partner, as both of them look to survive the forces lining up against them.