If you park a Pz4 anywhere. have the motor off, not moving at all, the main gun still moves by itself. About every 10 seconds, your view goes up rather quickly all by itself, as if you'd raised the gun. If you go to any of the other crew positions, this doesn't happen to your POV, and it's obvious that the whole tank itself ain't rocking. Nor do you see the gun tube move when you're not in the gunner's seat. But once you get in the gunner's seat, the gun starts moving around by itself.