Wagons to Backsight — J.T. Edson

The wagon train was heading for Backsight, the people looking to the West and a new home. Only Colonel Raines and his scout, Tom Blade, knew the danger that was stalking their every move. Then Tom Blade was dead, killed in an ambush, and Raines rode into Hammerlock to get help from the law. In Hammerlock he found four men who had been friends of Tom Blade.
Three of them were tall men, Texans who would catch the eye in any crowd. The Fourth was a small and insignificant-looking cow hand who hardly seemed to rate a glance. Yet when he spoke, the other three jumped to obey. In his presence the gun-hung toughs of Hammerlock grew silent and uneasy ... for his name was Dusty Fog.