Abstract: A pyrotechnically driven device for restricting the area of the nozzle throat in a solid propellant rocket motor is disclosed. In one embodiment, the device includes a piston support mounted to the rocket motor in the exit cone. A restrictor is attached to a piston which is supported by the piston support. The restrictor is movable from a retracted position outside the nozzle throat to a restricting position within the throat upon actuation of the device. The piston and attached restrictor are driven by a pyrotechnic driving means that is actuatable separately from the solid propellant of the rocket motor. A locking means locks the restrictor in its restricting position.