Originally developed in the early 1970's, the Auto-Assault Shotgun proved a rugged and reliable shotgun used by the United States Marine Corps during The Resource Wars between 2060 and 2077. It saw action in both the Yangtze and Gobi campaigns. Large quantities of the shotgun were acquired by The Mojave Rangers of Pullerville in Mid-2283 while scavenging desolate military bases north of the Mojave Wasteland.
By late 2283, the shotgun was being manufactured by the Gun Runners after striking a deal with Pullerville to provide Gun Runners with schematics in return for a minor manufacturing plant to be used for weapons and ammo production. The shotgun proved heavily popular with NCR soldiers stationed across the Mojave Wasteland when used with solid slugs, which were more than enough to bring down even the most hopped up of fiends.