Shotgun by Lesley Selander

5.30

Clay Hardin, a Deputy U.S. Marshal, is about to turn in his badge and take the job as the territory's Indian commissioner until the notorious Ben Thompson slays the marshal when he tried to make an arrest. Clay turns his back on a white-collar job and his girl to pursue the gang. Picking up a bounty hunter and a beautiful half-breed woman along the way, the little band follows the trail into Apache land where the lawman discovers that the outlaws plan to sell repeating rifles to the Indians.