The spherical section is the mounting, the traverse is kind of like a HL elevation motor on its side pressing the gun against a spring and the elevation is a wheel with a peg that engages a slot on the side of the gun. Kind of difficult to describe without a piccy, but obvious when you open it up
As for recoil, I'm not sure how you can seperate the main barrel from the rest of the assembly

Did they recoil in real life?