User blog comment:Willbachbakal/Singleplayer Weapons: Revolver Shotgun/@comment-1940820-20110404212322/@comment-1330314-20110405063312

The Ejectable Drum upgrade works a lot more like the Tommy Gun's drum magazine actually, since both involve using a drum to hold the weapon's rounds, but you're right. By Auto-Fire I mean that the Shotgun's fire rate goes from single-action to automatic, i.e. you'll be able to empty your entire clip in about two seconds just by holding down the fire button.