breech closer vs blockage

breech closer and blockage both are nouns.

Word	Noun	Adjective	Verb	Adverb
breech closer	Yes	No	No	No
blockage	Yes	No	No	No

As nouns, blockage is a hypernym of breech closer; that is, blockage is a word with a broader meaning than breech closer:

breech closer: a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing
blockage: an obstruction in a pipe or tube

Other hypernyms of breech closer include block, closure, occlusion, stop, stoppage.

breech closer (noun)	blockage (noun)
a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing	the act of blocking
	an obstruction in a pipe or tube
	the physical condition of blocking or filling a passage with an obstruction