It is a Md. 11. There were no fore runners, it was Remington's first auto shotgun and John Browning's first long gun deal outside Winchester - a mistake Winchester soon came to regret. The patents listed mean nothing really helpful, it was common in those days to list all of a company's patents that MIGHT apply. Savage later purchased production rights as well. Browning made an exclusive deal with FN of Belgium and that stated a long and happy run for both of them. Sadly, Europe priced their manufactoring out of reach for most American sportsman and Brownings are now made in Japan. The old "long recoil" operated auto loading shotguns have long been replaced by softer recoiling and cheaper to make gas operated rigs.
I have one my father purchased, used, about '46 from a disabled GI who had bought it new before WWII but would never be able to hunt again. It was lightly rusted, had no barrel rib and the plain grain stock was badly oil soaked. I took it in '69, had a Herter's rib installed, hot blued it myself, added a Herter's highly figured crotch walnut butt stock and forearm, then added a Pachmeyer recoil pad. My father loved it but died in '90 so it now sits in my gun safe. It's still a beautiful tool and as functional as it was when new; I love to use it in dove fields.