Don’t know what made me think of this scene: two riders are alone in a vast wasteland. Somehow, one of them has a broken leg, so the other one leaves him behind to go for help. As he rides a distance away, he hears a gunshot and looks down to see his empty holster.
It’s not exact, but this film Three Godfathers contains a scene in which a wounded man kills himself after being left behind in the desert.
Thanks, but that’s not it, but I read the synopsis and that movie sounds a lot darker than the comedy I always thought it was.
Not exactly a Western, but that sounds like a scene from The Stand (by Stephen King).