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. It was primarily developed as a lighter and more compact iteration of its predecessor, the M90, that didn't sacrifice on the weapon's extreme stopping power. With this in mind, 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.

This transition to a less powerful shell gauge produced the intended effect of reducing the materials needed in constructing the M91, decreasing its weight and making the weapon easier to use in general. In an effort to further increase this ease of use, the overall length of the M91's barrel and ammo tube was shortened to make it more compact. 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 an additional quality-of-life feature in the form of the coloured iron sights, which transition from blue, to yellow, to orange, and finally red with every two shells fired.

Despite it's increased effectiveness over its predecessor, the M91 has not yet been put into service across all branches of the UNSC Armed Forces, due to the increased production costs that come with manufacturing a completely new weapon model. Due to the importance of its original mission, Operation: RED FLAG, the UNSC Pillar of Autumn is one of few ships to be outfitted with a large complement of M91 Shotguns as of 2552.

Gameplay Information


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Developer Information






vde UNSC infantry weapons in SPV3
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