breech vs rear of barrel

breech and rear of barrel both are nouns.

Word	Noun	Adjective	Verb	Adverb
breech	Yes	No	No	No
rear of barrel	Yes	No	No	No

As nouns, breech and rear of barrel are synonyms defined as:

breech and rear of barrel: opening in the rear of the barrel of a gun where bullets can be loaded

Other synonyms of breech include rear of tube.

breech (noun)	rear of barrel (noun)
opening in the rear of the barrel of a gun where bullets can be loaded	opening in the rear of the barrel of a gun where bullets can be loaded