Last Gun: the Legend of John Selman — Gene Shelton

This is a work of fiction based on the life and times of John Henry Selman, one of the Old West's deadliest but least-known gunmen. Selman lived on both sides of the law-as leader of the vigilant Texas Home Guard and hired gun for the Seven Rivers gang. He was a deadly accurate shooter and left a bloody trail across the West. And in a gunfight that would create a legend, John Selman faced the West's most infamous outlaw, John Wesley Hardin, in one of the most notorious gunfights the Old West has ever known.