Vendetta (Western Frontier Justice War) by Jesse Storm

On a fateful Sunday, a gang called The Bronze Boys rob a local church, killing several people. One of the victims is Betty, wife of an ordinary builder named Myles. Myles is waging a personal vendetta against the gang. But he will have to face Albie Warwick, the head of the gang who is smarter and more shrewd than the rest of the Oregon bandits.