The shotgun uses a lever-action mechanism for reloading, similar to the Winchester repeating rifles of the time, by the same manufactuer. Commercially available pump-action shotguns were developed late in the 19th century. The Model 1887 was designed by the famous firearms engineer John Browning.
The particular specimen seen in Westworld appears to be a short-barreled 1887/1901, an updated version from the early 20th century. It was improved with a trigger block, the ability to fire higher pressure smokeless rounds, etc. Armistice's 1887/1901 seems closely patterned on the shotgun used by Paul Newman's character in the 1972 Western film The Life and Times of Judge Roy Bean.
- There is a continuity error involving the weapon during its use in the pilot episode, The Original. We see Armistice picking up a Model 1887 shotgun for defending the street during the Mariposa Saloon heist, but as soon as we see her shooting, the weapon is clearly a Winchester Model 1873 rifle (which Armistice uses frequently throughout the series).
- 12 gauge double-barreled shotgun - A double-barreled shotgun used for self-defence and hunting (most probably a Charles Parker 1878 model).
- Colt Model 1878 shotgun - A short, double-barreled "coach gun".
- Winchester Model 1873 - A lever-action Winchester rifle, one of the contemporaries of the 1887 shotgun.
- Winchester Model 1897 - A late 19th century, pump-action Winchester shotgun.