shooting iron vs side arm

shooting iron and side arm both are nouns.

Word	Noun	Adjective	Verb	Adverb
shooting iron	Yes	No	No	No
side arm	Yes	No	No	No

As nouns, shooting iron and side arm are synonyms defined as:

shooting iron and side arm: a firearm that is held and fired with one hand

Other synonyms of shooting iron include handgun, pistol.

shooting iron (noun)	side arm (noun)
a firearm that is held and fired with one hand	a firearm that is held and fired with one hand