Double Autos were made with an steel reciever. Steel model were later dropped for the "Twelvette" and "twentyweight" which was made with an aluminum alloy reciever only. Aluminum recievers came in half dozen funky colours with many model/barrel variations. Was in production for 18 or so years, about 70,000 made total. Inertia operated action and fairly mild recoil. Strange to shoot as they have a hollow "drum like" recoil. Discontinued in the early 1970's due to sagging sales in the U.S. Value varries but condition and model are everything... 300-1000 bucks at the top. Brownings son Val was the brainchild, first radical departure from the traditional "humpback" Browning design. I own one and shoot it on a regular basis, mostly crows and upland game.