A Noose for the Desperado by Clifton Adams

Outlaw Tall Cameron rides in to Ocotillo, Arizona and is immediatey set up by Marta, a Mexican hell-cat, for a gunning down by a bent US Marshall. Cameron survives the attempt and works his way into the local gang, joining in the vicious raids against smuggling parties from south of the border. Along the way we soon realize that Tall Cameron isn't much of a noble rogue, but is about as unhinged as they come. In fact, no one in Ocotillo is dealing with a full deck. It's the last town north of Hell, where loyalty lasts as long as the next silver dollar. It's dark and bloody, and as bleak as a desert-fried skull.