The Heckler & Koch CAWS (H&K CAWS) is a prototype automatic shotgun—designed as a combat shotgun—co-produced by Heckler & Koch and Winchester/Olin during the 1980s. It was Heckler & Koch's entry in to the U.S military's Close Assault Weapon System program.
Superior version of the combat shotgun, but also a fair bit more expensive. Longer range and more shells per burst, but smaller magazine capacity. It does more damage per shot than the FN FAL but less damage per burst.
Outside of the Fallout universe, the H&K CAWS was a recoil-operated, bullpup-configuration shotgun prototype designed to fire high-impulse shotshells using tungsten buckshot or flechettes with an effective range of 100–150 meters and a 10-round box magazine. It had a fire selector switch similar to the G11, with a full-automatic firing rate of approx. 240 rounds per minute. It never reached production due to the cancellation of the CAWS project by the US.