You've got 2 combinations of elevation/rotation. First for the frame, then for the gun.
If you liken it to how tanks are modeled, the ring is the turret, and the gun flex mount is the MG on top of the tank's turret. Only the gun has a limited range of motion, and you would have to constantly jump back to the turret, move its position/orientation, then jump back to the gun to see if what you want to hit is in your field of fire.
Rinse/repeat if the target is moving. It's too clunky. You need a way to do that all from 1 position (i.e. no jumping from turret to gun and back)