Abstract: A cartridge receiving drum construction for providing gas-tight closure of a separation interstice between a gun barrel and cartridge receiving drum which is rotatably mounted in a housing of the gun adjacent the loading end of the barrel, comprising a drum having a plurality of through bores defining projectile guideways for receiving a cartridge which are alignable with the gun barrel. The end of the drum adjacent the gun barrel defines a front surface with a circular groove therein concentrically arranged around each projectile guideway. An elastic seal capable of withstanding a very high temperature is arranged in the groove and a plurality of relatively small diameter bores extend inwardly from the inner end of the groove and are connected laterally into a similar small diameter bore into the guideway at a spaced location from the front face of the drum barrel.