action mechanism vs gun

action mechanism and gun both are nouns.

Word	Noun	Adjective	Verb	Adverb
action mechanism	Yes	No	No	No
gun	Yes	No	Yes	No

action mechanism (noun)	gun (noun)
the operating part that transmits power to a mechanism	the discharge of a firearm as signal or as a salute in military ceremonies
	a weapon that discharges a missile at high velocity (especially from a metal tube or barrel)
	large but transportable armament
	a hand-operated pump that resembles a pistol; forces grease into parts of a machine
	a pedal that controls the throttle valve
	a professional killer who uses a gun
	a person who shoots a gun (as regards their ability)

action mechanism (verb)	gun (verb)
	shoot with a gun