#breechblock__breech_closer  a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing
  supertype:  closure__block__occlusion__stop__stoppage  an obstruction in a pipe or tube; "we had to call a plumber to clear out the blockage in the drainpipe"
  part of:  breech__rear_of_barrel__rear_of_tube  opening in the rear of the barrel of a gun where bullets can be loaded
     part of:  cask__barrel  a cylindrical container that holds liquids

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