Gun Runners — Robert A. Carter

A gun-running ring in Sanderson is selling rifles to Mexican bandits over the border. When a US marshal is sent to investigate he is killed by Juan Martin, a member of the gang. Marshal Curtis is sent to escort Martin to Waco for questioning but on the journey the killer is silenced forever. Curtis is given the task of tracking down the rest of the gun-runners. His prime suspect is D.J. Souther, the leading citizen of Sanderson.