Abstract: A grenade machine gun or other weapon which employs superelevation of the barrel comprises a barrel unit and an aiming system mounted upon a support. The aiming system is mounted to the weapon and the support by a coupling unit. The aiming system comprises an imaging and display unit for displaying an image of a scene including a target, angle encoders for providing a signal representing displacement of the imaging unit in elevation relative to the support, and a control unit, e.g. a computer, for selecting either of two states for the coupling unit. The first state entrains the imaging unit to move with the barrel. The second state secures the imaging unit to the support and allows the barrel to move relative to both, i.e. during superelevation of the barrel. The coupling unit may comprise a first part connected to the weapon for rotation in elevation with the barrel unit and a second part connected to the imaging unit.