stoppage vs breechblock

stoppage and breechblock both are nouns.

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

As nouns, breechblock is a hyponym of stoppage; that is, breechblock is a word with a more specific, narrower meaning than stoppage:

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breechblock: a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing

Other hyponyms of stoppage include breech closer, plug, stopper, stopple, vapor lock, vapour lock.

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the act of stopping something	a metal block in breech-loading firearms that is withdrawn to insert a cartridge and replaced to close the breech before firing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