No God West of Hays

In the 1870s, a young John Wesley Hardin is just beginning to develop his gunslinging reputation. At eighteen, he is already a killer and in Abilene adds to his legend by shooting a man for snoring. He goes on the run pursued by the town's marshal, the formidable Wild Bill Hickok. While on the run, Hardin falls in with a vicious gang of outlaws and falls in love with one of their hostages. He realizes that there are too many of them for him to take on alone. His only option is to ask Hickok for help.
This story first appeared in Alfred Hitchcock's Mystery Magazine.