3:10 to Yuma (1957)

Glenn Ford and Van Heflin may have both provided their best performances in this movie. I'm pretty sure that the ending is not the one that was originally written and even if it is, it doesn't ring true. Luckily, the rest of the movie has already done its job and the ending isn't that critical to the psychology. Which psychology, by the way, escapes mere mortal's grasp at about 2:45, but Heflin pulls it off with aplomb.