breech closer(n = noun.artifact) breechblock - a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing;
is a kind of block, blockage, closure, occlusion, stop, stoppage
is a part of breech, rear of barrel, rear of tube

bear's breech, breech, breech action, breech birth, breech delivery, breech pin, breech presentation, breech screw, breech sight, closer, file closer, frank breech, frank breech delivery