An arrangement for rapidly stopping the movable parts of machine cannons with independent external drives wherein a rotating element, which rotates in dependence to a rotating control drum drivingly connected to the breech block, is stopped at misfiring or delayed firing within the breech block locking period of the firing cycle by a locking element which is actuated by propellant charge gas pressure. The arrangement of the invention prevents a shock-like braking and transfer of the kinetic energy of the movable parts of the machine cannon and provides for an automatic release of the blocking element.The arrangement includes a rotating rod spring coaxially mounted within the control drum by means of which the kinetic energy of the rotating masses of the breech drive are elastically braked. Such energy transfer can even be effected with a delayed ignition because by means of positive interruption of the propellant charge gases traversing an annular chamber the release of the blocking element is prevented and it is not lifted off a cam disc. This blocking element can, however, be separately lifted of the cam disc by means of a release lever.