Rheinmetall AG is an actual company in the real world known for making weapons and military vehicles.
↑Fallout 2 item description: "The German Rheinmetal AG company created the ultimate minigun. The Vindicator throws over 90,000 caseless shells per minute down its six carbon-polymer barrels. As the pinnacle of Teutonic engineering skill, it is the ultimate hand-held weapon. Min ST: 7." (PRO ITEM.MSG (Fallout 2))
↑Van Buren tech demo in-game description: "Manufactured by Rheinmetall AG, this 9mm machinepistol is capable of one-handed use for both single shot and burst attacks. Though it is wildly inaccurate, its potential for loads of short-range damage is high."