Edwin S. Porter’s 1903 “The Great Train Robbery” is widely regarded as one of the first major narrative films — using a then-advanced clutch of techniques to tell a real, almost epic (at 12 minutes) story rather than simply to record a vignette. It also helped solidify the Western as a form specially suited to this new medium, even if it was shot in New York and New Jersey.

Telling a tale that begins that same year, Brian Skiba’s new “Gunslingers” is another “eastern Western,” shot in Kentucky. But the prolific writer-director’s latest provides an illustration of how the genre became somewhat fossilized via formulaic writing and overexposure even before 1950s television began churning out Western content in bulk. The modern-day equivalent of a Poverty Row “oater,” it’s more violent and profane than the sagebrush programmers of yore. Still, those factors can scarcely hide a serious lack of conviction...