That photo appears on page 340 of Firearms of the American West, 1866-1894, by Lous Garavaglia and Charles Worman. The caption reads:
"The interior of a saloon in Albany County, Wyoming. The Iver Johnson or similar small-frame revolver stuck muzzle down in the glass at the bartender's left adds an element of humorous intrigue to the furnishings. (Courtesy Wyoming State Archives and Historical Dept.)"
No date is given, I'm afraid.
CC Griff