S&W shotguns are very underappreciated. I own and shoot a 12ga. and 20ga. 1000Ms and love them. They were made from the early to mid 70s through the mid 80s, if I'm not mistaken, in Howa, Japan. A lot of people didn't like them due to their poorly designed gas system.
If you shotgun is a 1000, its a 2 3/4in chamber, if its a 1000M its a 3in chamber.
Info is really hard to come by with these guns a lot of people didn't like them.