R. S. Belcher 
The Shotgun Arcana [EPUB ebook] 

1870. A haven for the blessed and the damned, including a fallen angel, a mad scientist and a pirate queen, Golgotha has come through many nightmarish trials. But now an army of outlaws, lunatics, serial killers, and cannibals are converging on the town, drawn by a grisly relic that dates back to the Donner Party… and the dawn of humanity. Sheriff Jon Highfather and his deputies already have their hands full dealing with train robbers and several brutal murders. But with some of the most vicious killers on Earth riding into Golgotha in just a few days time, the town and its people will be tested as never before—and some of them will never be the same.