M90A shotgun

"I believe that the sound of racking the pump of a shotgun is universally recognized as "kiss your ass goodbye"."

- Anonymous E2-BAG/1/7 serviceman

The M90A Close Assault Weapon System, or M90A CAWS, is a powerful pump-action shotgun in the service of the United Nations Space Command as a standard close-quarters assault weapon. It is a variant of the M90 shotgun that is part of the widespread DTM series produced by Weapon System Technologies.

Design
The M90A fires the tremendously powerful 8-gauge magnum cartridge, generally the 0000-variant, feeding from from a 6-shell dual-tubular non-detachable. The weapon has an overall length of 123.9 cm and a barrel length of 61 cm. It weighs 5.4 kg empty and 5.7 when fully loaded. It has a characteristic shape, with the prominent non-detachable magazine positioned above the barrel, atop which are positioned a set blue-glowing illuminated iron sights. Below the barrel, the forend (or "pump") follows a protruding rod. Into the forend is inserted a reddish button. On the weapon's left side, mounted along the barrel, is a flashlight. The adjustable stock, pistol grip and forend of the weapon have a matte black finish, with the rest of the weapon being a dark, metallic grey. The receiver port of the weapon is located on top of its body, roughly in-line with the trigger on the underside. It features a chrome finish, distinguishing it from the rest of the weapon's body.

Functionality
When using standard 0000 8-Gauge Magnum ammunition, the weapon does not fire a single projectile but a spray of small pellets known as "buckshot", each of which leaves the weapon's barrel travelling at 300–400 m/s in a plume of fiery gasses. After the weapon is discharged via the depression of a trigger positioned at the top of the pistol grip, the forend of the weapon (which acts as a foregrip for the user's non-dominant hand) must be retracted towards the stock by the user, ejecting the spent shell of the round just fired. When the forend is fully retracted, the way will have been cleared for an elevator to position a new shell from the magazine so that it can be loaded as the forend is once again pushed forward in the direction of the muzzle. At any point, the weapon's non-detachable magazine can be topped off or reloaded with more individual shells via the receiver.

Performance
The M90A is a simple weapon, quite easy for any shooter to make use of. When firing standard ammunition, it possesses an effective range of 40m, an extreme degree of stopping power at close range, and a situationally beneficial lack of propensity to cause unintended damage to hard targets such as spacecraft hulls. It features noticeably milder recoil than other variants of the DTM series. A marine of E2-BAG/1/7 noted that the M90A's usefulness outside of its specific role was somewhat limited, musing that it would perhaps be better thought of as a tool than a weapon.

History
The M90A was prominently employed by during the Battle of Earth, including the Battle of Mombasa, the Attack on Crow's Nest, and the Battle of Voi, by UNSC marines, NMPD officers, and in at least one case, civilian combatants. It was also used by during the Battle of The Ark. After the war, an M90A was displayed in the Museum of Humanity.

UNSC remarks
The following remarks were obtained by Dr. Robert McLees as part of his document Machines, Materiel and Munitions from the Human-Covenant Conflict, 2525 - Present from anonymous members of the UNSC Marine Corps unit E2-BAG/1/7.
 * “The kick is milder with the As — not that it was that bad to begin with — sometimes progress just seems like change, if you catch my meaning.”
 * “The adjustable stock on the M90 works just fine, but I’ve got a soft spot in my heart for the WST DTM/LE model — old habits die hard, I guess."
 * "I believe that the sound of racking the pump of a shotgun is universally recognized as "kiss your ass goodbye"."
 * “Actually, I think the jury is still out on whether it means ‘STFU and STFD’ or ‘you ain’t gonna make it.”
 * “The action I saw against the Flood on Delta Halo was pretty limited — thankfully — and you would think that the M90 would be the ultimate anti-Flood weapon, right? Except that a shotgun is effective because it delivers a massive shock to a delicately balanced system of organs and the Flood don’t have that delicately balanced system of organs — it’s like shooting a mike foxtrot tree! All you can really hope to do is disassemble them as rapidly as possible in the correct order.”
 * “The shotgun is a specialist weapon — it has its uses, but they are limited. Maybe it is more accurate to call it a tool, as opposed to a weapon?”

List of appearances

 * ''Believe
 * Enemy Weapon (First appearance)
 * Halo 3
 * Halo 3: ODST