breechblock vs stoppage

breechblock and stoppage both are nouns.

Word	Noun	Adjective	Verb	Adverb
breechblock	Yes	No	No	No
stoppage	Yes	No	No	No

As nouns, stoppage is a hypernym of breechblock; that is, stoppage is a word with a broader meaning than breechblock:

breechblock: a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing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 breechblock include block, blockage, closure, occlusion, stop.

breechblock (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a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing	the act of stopping something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