M90A Close Assault Weapon System
Official designation: M90A CAWS
Length (o/a): 123.9 cm (48.8 in.)
Length (barrel): 61 cm (24 in.)
Weight (empty): 5.4 kg (11.9 lbs)
Weight (loaded): 5.7 kg (12.6 lbs)
Cartridge: 8 gauge magnum (3.75”)
Max. effective range: 40 meters (131 ft)
Muzzle velocity: 300-400 m/s (980-1300 f/s) [depending on the ammunition]
Magazine capacity: 6 rounds
Rate of fire: pump-action
Unit Replacement cost: cR. 2200
The M90 is a pump-action magazine-fed (dual tubular non-detachable type) weapon. It fires 8 gauge magnum (3.75”) rounds.
The Weapon System Technologies DTM series is the most common shotgun in the galaxy—used by UNSC Special Forces, civilian security personnel, and sportsmen alike.
Although many prefer the larger magazine capacity and rate of fire of the MA5 and BR55, the M90’s immense stopping power, ease of use, and reduced capacity for puncturing the hulls of spacecraft over many other UNSC weapon systems (with standard 0000 ammunition) are greatly appreciated.
“The kick is milder with the ehs—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 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 balance 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?”
 The DTM series of shotguns are available in 20gauge -10gauge for the civilian market—the 8gauge is only sold to law enforcement and military agencies.
CPL GROVE, ROBERT 081225-78081-RG was employed as a law enforcement officer in Elysium City prior to entering the Marine Corps; he is referring to the WST DTM/LE (law enforcement) model which had a solid stock and no pistol grip.