One of my college professors worked on long range ship gun munitions in the late 70s that were steerable through analog computers. He described the spinning of the round was used to drive an oil pump. Reservoirs around the circumference contained oil which could be moved from one side to another. As the round spun the oil was moved back and forth to change the center of mass, steering the round in flight. All controlled by a radio connection back to the ship. Very cool stuff.