The Chaney Edge by Robert Vaughan
It Takes Two Loyal Brothers to Outsmart a Texas Outlaw.
Buck Chaney first crosses paths with Rufus Blanton on a West Texas train car halted suddenly in the night. Rufus is on board-and set on robbing every passenger. When a shootout with Buck leaves two of his gunmen dead, the outlaw gets away with his life - but without any loot. He'll come back to haunt Buck Chaney and his brother Lance.