automatic vs automatic firearm

automatic and automatic firearm both are nouns.

Word	Noun	Adjective	Verb	Adverb
automatic	Yes	Yes	No	No
automatic firearm	Yes	No	No	No

As nouns, automatic firearm is a hypernym of automatic; that is, automatic firearm is a word with a broader meaning than automatic:

automatic: a pistol that will keep firing until the ammunition is gone or the trigger is released
automatic firearm: a firearm that reloads itself and keeps firing until the trigger is released

Other hypernyms of automatic include automatic gun, automatic weapon, handgun, pistol, shooting iron, side arm.

automatic (noun)	automatic firearm (noun)
self-loading rifle capable of automatic fire	a firearm that reloads itself and keeps firing until the trigger is released
a pistol that will keep firing until the ammunition is gone or the trigger is released

automatic (adjective)	automatic firearm (adjective)
operating with minimal human intervention; independent of external control
without volition or conscious control
resembling the unthinking functioning of a machine