El Dorado (1967)

Hired gunman Cole Thornton (John Wayne) turns down a job with Bart Jason (Edward Asner) as it would mean having to fight an old sheriff friend (Robert Mitchum). Some months later, he finds out the lawman is on the bottle and a top gunfighter (Christopher George) is heading his way to help Jason. Along with young Mississippi (James Caan), handy with a knife and now armed with a diabolical shotgun, Cole returns to help.