Outland is a 1981 science fiction film starring Sean Connery as the new federal marshal for a mining colony on a moon of Jupiter. The film was directed by Peter Hyams and contains similar themes with the classic western High Noon.
The following weapons were used in the film Outland:
The main weapon seen in this movie is a sawed off Browning 2000 shotgun. Federal Marshal William O'Niel (Sean Connery), Sheppard (Peter Boyle), as well as other marshals are seen using the shotgun, but it appears that there was only one practical shotgun used in the film. The two hitmen hired to kill O'Niel use them as well, with infrared scopes attached. In the scenes where multiple guns are present it's likely the others are props. Interesting to note is that one of the hitmen is P.H. Moriarty, who would later be seen as Hatchet Harry in Lock, Stock and Two Smoking Barrels. O'Niel's shotgun is tapped for the giant scope mount that the hitmen use. You can see the small screw hole just forward of the loading port. This supports the "one gun" theory.