Riders of the barren plains I. J. Parnham.

When Jeff Steed rides into Carmon and gets caught up in a bank raid, he has to escape from both Sheriff Cassidy Yates and the bank raider Blake Kelly. He assumes the identity of a dead man: the leader of a supply convoy travelling across the Barren Plains to the silver miners at Bleak Point. But Jeff finds the convoy being escorted by the lawman who's been trying to catch him - and the bandit he double-crossed in Barren Plains...