Lol, it's the Pancor Jackhammer select fire 12g shotgun. Only three were made, this one and two other prototypes for military testing. It actually did great in the tests, although they eventually passed on it. By then the company had gone bankrupt, though, because they weren't able to take any other contracts pending US Army adoption. It was made in 1987... I think somebody had gone to the movies once or twice the year before
I think it would actually be a really sweet project to build one of these up for USCMC trooping. Not that I need ANOTHER project, but what can ya do : /
EDIT:
Something like this