Shootout at the Circle-R Corral

From publisher blurb: The Iron Men plague Kempe County’s financial establishments. This gang of bank robbers relies on an array of gizmos and weird science creations to give them a decided edge over any small-town law dogs that might oppose them. Time to call in a posse, amigo! Although this adventure is set in “Kempe County,” moving it elsewhere is as simple as changing the place names.