In the case of delayed firing of a cartridge or a so-called hang-fire condition in an externally powered firing weapon there must be prevented that further cartridges are fed into the firing weapon. In a known safety or monitoring apparatus of this type a deflector must be pivoted such that the infed cartridges, instead of arriving at the firing weapon, arrive at an ejection channel. The change-over of this deflector requires high acceleration forces because a great mass must be pivoted through a large pivot angle in a short period of time. In accordance with the invention the deflector comprises two segment members which are displaceable in the direction of the cartridge axes, one of which segment members selectively protrudes into the travel path of the cartridges.