When the player is connected to a static autonomous weapon system (HMG,GMG) and activates the PIP view (no default key afaik), the view of the static weapon is pitched down and shows the barrel of the gun instead of where the gun is actually pointing at.
Not to be mistaken with the turret view when controlling the gun directly, only the PIP is affected. Also the AI of the static weapon should be disabled. {F24940}