The Lone Gun (1954)

"They threw him a badge...a belt-full of bullets...and the toughest clean-up job in the West !"

Cruze arrives in town and when he stands up to the three Moran brothers, he gets appointed Marshal. First the brothers kill a rancher while framing another man. But when the jailer is murdered, Cruze gets evidence the Morans did it. He tries to raise a posse to chase them down but the townsmen refuse to go. So he rides off by himself to face the three of them.