The unbranded four-chamber .50 caliber revolver is a handgun favored by Ornix. It fits his minimum requirements of being ridiculously high powered and man-portable. Ammunition capacity is not a consideration.
Unlike Thad, Ornix is shown to handle the weapon with a degree of skill.
The .50 caliber revolver is completely discharged over the course of The Dualist, and may or may not have been brought aboard the Sabrosa.