breech closer vs stoppage

breech closer and stoppage both are nouns.

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

As nouns, stoppage is a hypernym of breech closer; that is, stoppage 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breech closer: a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing
stoppage: an obstruction in a pipe or tube

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

breech closer (noun)	stoppage (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a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing	the act of stopping something
	an obstruction in a pipe or tube
	the state of inactivity following an interruption