It's a DARPA study called "The Meanderings of a Weapon Oriented Mind When Applied in a Vacuum Such as the Moon" and it was made on July 15, 1965, and declassified on December 31, 1971. This was an early "bluesky" paper on the creation of a first generation of infantry weapons for use in hard vacuum and a minimum of gravity. While not particularly fierce - it was thought that holing a space suit was a mission-kill at the time - these weapons are likely to be widely encountered in places where smart submachineguns can't be banged out in the nearest nanofabricator, but there's a ready source of tube and compressed gas. They're also optimized for minimal mass, in order to reduce their total cost of ownership (likely to be dominated by their launch costs, presumably via chemical rockets).
Please, enjoy the space oddity. It's in the public domain now, so rehost the hell out of it so it never ends up lost!