A stripper (5) is arranged at a breech ring of a large-calibre firearm. A ramming unit is arranged to insert a shell (11) and a charge (10) into the bore and chamber of the firearm during an insertion process. During the extraction process of the ramming unit which follows the insertion process the stripper goes into coaction with the bag charge and retains this in the chamber position. The stripper coacts with blocking means which during at least part of the insertion process prevent the stripper from being turned out. At a predetermined insertion position the ramming unit (12) achieves a releasing of the blocking means and at the releasing of the latter the stripper is released and can assume a turned-out position. The stripper is actuated to the turned-in position by means of a closing mechanism, and during this actuation the blocking means are prepared to again retain the stripper in the turned-in position at a renewed ramming.