I have a mossberg 600AT. I was looking to gain a little info about it. It is very similar to the 500. It has a vented rib, set full choke, and a 30in barrel. This is one of the best shooting shotguns that I own and deff my go-to gun. It was my first shotgun and until now never really wondered about the history behind it. I have honestly never really heard of a 600 before, other than owning one of course. Any background would be great. Thanks.