The Jackhammer has a unique appearance thanks to its bullpup layout, combat sight rail and weight-reducing Rynite plastic construction. It is gas-operated and fully-automatic only. The floating barrel is driven forward by the gas piston with each shot to allow the 10-round drum magazine to rotate, before moving backwards to form a gas-tight seal. The magazine can either be loaded with ordinary 12 gauge shotgun ammunition, or a special “ammo cassette” can be used. This cassette comes preloaded from the factory with primer, powder and projectiles in 10 individual packages, covered by a plastic film that is removed before loading the magazine. The empty cassette is sent back to the factory after firing to be reloaded.
The bullpup layout allows the Jackhammer to retain a 525mm barrel in a relatively short 787mm overall length, and the Rynite plastic construction keeps weight down to 4.57kg unloaded. These two factors make the jackhammer quite easy to wield for a fully automatic shotgun. The Jackhammer has a fully-automatic rate of fire of 240RPM, which is quite low for an automatic weapon such as a sub machinegun or assault rifle, but the powerful 12 gauge ammunition produces tremendous recoil that would make the jackhammer impossible to control at a higher rate of fire.