It seems that the U.S. military has long been attempting to convince itself of the need for a full-automatic combat shotgun for more efficient close-quarters work. Such was the purpose of the HK CAWS, born of the "Close Assault Weapon System" (CAWS) program intended to find a new lethal solution at the most intimate of combat ranges. The HK CAWS entry was headlined by the storied West German concern of Heckler & Koch best known for their ubiquitous HK MP5 series submachine guns with participation from the Winchester/Olin Corporation - the former best known for its long-running rifle line and the latter for its ammunition products. For the purposes of the CAWS entry, Heckler & Koch handled development of the gun system proper with Winchester and Olin working together to develop the specialized ammunition intended for the weapon.
The CAWS program was in consideration throughout the 1980s, entering testing with the American military, before falling to naught.
Work ultimately begat an end-product with a then-non-traditional "bullpup" configuration which featured the action set behind the trigger group and pistol grip. In this way, a full-length barrel could be retained while promoting a more compact overall length for the gun body itself. The oversized receiver not only contained the majority of the internal workings but also doubled as the shoulder stock when firing. The gun was devised as ambidextrous which did not favor one particular shooter over the other. The receiver was largely rectangular and featureless with a straight detachable box magazine inserted into the frontal base section of the shoulder stock. Along the top of the receiver was a carrying handle encompassing the charging handle - accessible by either free hand of the operator. The wide gap found in this ring also ensured a gloved hand could access the handle to cock the weapon. The pistol grip was mounted near the center length of the design for the appropriate balance with the integrated curved trigger assembly rounded along two sides by a thin guard ring. The fire selector switch was added to both sides of the gun frame to formally complete the total ambidextrous features of the gun. The fore-end was smooth and featureless, tapering towards the barrel of which only a short section protruded ahead. The barrel assembly lacked any sort of muzzle attachment and kept a smooth, cylindrical uninterrupted shape. As with some of the other HK products of the late-Cold War years, the HK CAWS itself proved a futuristic-looking weapon.
The HK CAWS was fed by a belted 12-guage (18.5x76mmR), 10-round box magazine. The integrated fire selector offered a standard safety, semi-automatic, and full-automatic function for firing. The primary action (an HK patent) was of recoil-operation common to machine guns with a rate-of-fire between 200- to 300-rounds-per-minute being reached. Effective range stood at approximately 150 meters - any target caught within the sights of the gun was sure to be utterly decimated through the repeat-fire nature of the weapon. A optical scope was optional for increased accuracy as close-to-medium ranges.
As good an entry as the CAWS appeared on paper and in trials, the system simply did not convince U.S. military authorities who decided to keep with their current collection of manual pump-action and semi-automatic combat shotguns. This lack of endorsement led to the CAWS program eventually being cancelled within time. The CAWS product was not revisted after its short window of attention during the 1980s.