AA12 is a really cool firearm I. I think the original Blowback version from the 70's is truly exiting though!
http://world.guns.ru/shotgun/usa/atchisson-aa-12-e.html
And I wasn't meaning to reserect such an old thread but I wanted people to know that you didn't have to cycle all the rounds through a pump shotgun to unload one.
Brother In Arms