When using the newly added FFV from the gunner/commander position of a MBT (tested with Kuma), the turned in position seems to inherit the maximum horizontal and vertical movement from the turned out (FFV) position. The gunner of the Kuma can turn the main turret only 180° (90° in each direction) instead of 360° and the commander has also a limited turning ability.
This occurs when the player has turned out of the gunner/commander position at least once and then closes the hatch again.