The ISAAA-18/12 Automatic Shotgun is a TL-12 version of
Military Police Systems
AA-12
automatic assault shotgun. Claude Murdoch did the conversion into FF&S stats.
The Instellarms Auto Assault - 18/12 is the TL-12 version of it's best selling close quarters battle shotgun.
Of the bull-pup type configuration, this selective fire auto-gun fires the standard 18mm x 70mm round, found throughout space, at a selective SA 5, or a full auto mode of 300 rpm (ROF 5) from 15 round box magazines, or 30 or 60 round drum magazines, with the latter being the standard fitout for the weapon. 30 round drums are usually found employed with the short barrel, in the close quarters combat role, while the 15 round magazines are used to employ the more specialized combat or crowd suppression rounds.
The gas operated system utilizes the millennium old principle of "Constant Recoil", whereby the bolt group runs out on a long two stage recoil/operating spring, eliminating the majority of the felt recoil and thus increasing accuracy (action modifier of .75 for FFS1 design).
The TL 12 version is machined out of Superdense metallic components, with composite laminate furniture. This results in a lighter, more robust weapon, requiring no lubrication, and thus optimized for operations across the environmental spectrum, including vacuum.
The barrel is of the quick change type, with all mounting a fore grip on the barrel, capable of locking in the vertical position, or horizontally along the barrel, allowing accessories to be mounted beneath the barrel. The foregrip consists of a top full length Imperial Mil Standard 950 rail assembly, while the left and right foregrip area comprises 15cm long Imperial Mil Standard 950 rail mounts. All versions of the barrel are equipped with a variable choke muzzle brake, and can be fitted with the 17cm Close Quarters Combat size (short range 10m, Cr 35), the 41.75cm Standard Barrel size (short range 50m, Cr 85), or the 71.3cm Heavy Barrel (short range 100m, Cr 218, short range 130m w/ bipod, Cr 81), for sustained fire.
While the top rail is equipped only with iron sights, the weapon can be fitted with any sighting/pointing device, light or additional fixture built with Imp Mil Standard 950 lugs. Items available for mounting include a bipod, or the 1.8 cm Common Support Weapon, which clip to both of the side rails, or the Superdense Polearm Combat Device, which can be attached to either side rail, leaving a large volume of lug area on the rails available for other fittings.