The Last of the Fast Guns.

A rich, dying Easterner hires gunfighter Brad Ellison to find his brother and heir in Mexico. En route, it becomes clear to Ellison that his is a dying profession. At a remote rancho, Ellison enlists ranch foreman Miles Lang to help him search the hills where the missing man is rumored to have lived. They find nothing ...except that someone wants to kill them; and Ellison becomes wrapped in a maze of double crosses.