Originally posted by rustiswordz
its a Jackhammer. It uses preloaded colour coded magazines.
The feed system consists of the 10 shot, revolver type detachable cylinders, named "Ammo Cassette". The cassette may have 10 chambers for more or less conventional 12 gauge shotgun shells, or may be designed like the "cap and ball" era revolver cylinders. In the latter case, each chamber is factory pre-loaded with powder, primer and a projectiles of one or another type, then hermetically sealed in the plastic film cover. Prior to load the "Ammo Cassette" into the gun, one must remove the plastic sealing and then insert the cassette. When all charges from the cassette are fired, it can be disposed of or sent to the factory for reload.
This doesn't look like one at all... 
Designed and built by Maxwell G. Atchisson in 1972. This prototype weapon, which was a handmade, tool-room test platform, it gave birth to an entirely new class of military weapon, the assault shotgun. By using some M16 rifle components, in order to reduce development costs and to facilitate ease of fabrication, the Atchisson has nearly the same dimensions and configuration as the M16 rifle. For maximum effectiveness 00 buckshot should be used, but either #4 buckshot or 1 ounce slug can be used equally well. Of a simple design, its barrel screwed into a long, tubular receiver which housed the bolt and the recoil spring. A Model 1918 BAR trigger mechanism, equipped with a Thompson Submachine Gun pistol grip was used as the trigger assembly.
Between the years of 1973 and 1979 Maxwell Atchisson designed an improved version of his 1972 prototype. With many improvements to the original prototype, most visibly being the entire mechanism being closely encased in twin stock halves forming a clamshell arrangement. The production clamshell was made out of glass-reinforced Zytel, the same plastic used on the M16A2 rifle. Production was to be in the US and Korea (by Daewoo). The pre-1984 version was produced to the 1981 design specs, while the 1984 version had some improvements, most notable the addition to mount either an M6 or M7 bayonet (as used on the M16 family of rifles) and the removal of the checker non-slip pattern from the fore-arm of the clamshell. Plans where drawn for an ambidextrous selector lever, to be introduced in a later production model. All production Atchisson's had the ability to launch 22 mm NATO standard rifle grenades, by the inclusion of integral gas check grooves near the muzzle. The square cut gas check grooves can be utilized as mounting surfaces for auxiliary muzzle attachments such as choke tubes, a shot spreader and flash & sound suppressors. There are 2 magazines designed and proven for the Atchisson at the time. The 7 round, single-column, single-feed box magazine and the 20 round assault drum. In Korea a 3rd magazine was under development, being a 10 to 12 round, staggered, double-column, single-feed box magazine. The following figures might represent what a 10 or 12 round fully loaded magazine might have weighted, 10 round magazine: 1.20 kg, 12 round magazine: 1.44 kg.
