Have you guys seen these? http://www.reapercamo.com/product60.html Black Aces Pro Series 500 Kit for Mossberg 500/590 Price: $99.00 The Black Aces retro receiver kit transforms a standard shotgun into a pump action, magazine-fed tactical weapon. The receiver kit includes all the parts, tools and instructions to replace the receiver and internal components to allow a Mossberg 500/590 (A1) to accept readily available Saiga 12 magazines (5, 8, 10, and 12 round sticks or 12 and 20 round drums). All tools and easy installation instructions are included. No gunsmithing required - install and be ready to fire in minutes!