specially adapted for sealing the gap between the forward end of the cartridge chamber and the rearward end of the barrel, e.g. sealing devices for revolvers or revolver-type guns

Full Title

Breech mechanisms, e.g. locks > Mounting of breech-blocks; Accessories for breech-blocks or breech-block mountings > Obturating or packing devices for gas leak prevention in breech mechanisms > specially adapted for sealing the gap between the forward end of the cartridge chamber and the rearward end of the barrel, e.g. sealing devices for revolvers or revolver-type guns