The M91 Close Assault Weapon System (M91 CAWS), more commonly referred to as the M91 Shotgun, is a United Nations Space Command infantry firearm and the successor to the M90 Close Assault Weapon System.

Overview & Background

The M91 Shotgun is a pump-action, tubular-magazine-fed weapon designed for close-quarters combat in both urban and shipboard environments. The most significant change made to the weapon was with the ammunition used; instead of the standard Soellkraft 8-Gauge shell, the M91 uses the Soellkraft 12-Gauge shell. While the pellets are only half the size of those found in the 8-Gauge shell, the 12-Gauge shell contains 30 pellets instead of 15, technically making both shells equally powerful as each other.

While this change decreases the weapons effective range and reduces the maximum ammo it can carry from 12 shells to 8, these drawbacks are offset by the increased pellet count of the 12-Gauge shells used, which allow the M91 to retain its ability to deal suppressive fire to targets in confined areas and at medium ranges, without affecting its performance at close ranges. The M91 features colored iron sights, which transition from blue, to yellow, to orange, and finally red with every two shells fired.

Gameplay Information


  • Very high damage at close-quarters combat.
  • Can be reloaded at anytime.
  • Very effective against shields.


  • Not good for long range combat.
  • Once the barrel is empty, reloading all eight shells takes long enough to leave the player vulnerable to attacks.

Developer Information



  • The lights on the shotgun change depending on ammo.
    • Full: Blue
    • Half: Orange
    • Empty: Red
  • Before all levels were released, the shotgun's lights were green, making its appearance similar to the M90 Close Assault Weapon in Halo 2.


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