Well, you made me curious so I looked up MI statutes and they(air handguns) appear to be OK if you are over 18
I give you section 166
166 FIREARMS LAWS OF MICHIGAN — STATUTES
SPRING, GAS, OR AIR OPERATED HANDGUNS
Act 186 of 1959
AN ACT to regulate the use of certain spring, gas or air operated handguns and to provide a penalty for violation of this
act.
History: 1959, Act 186, Eff. Mar. 19, 1960.
The People of the State of Michigan enact:
752.891 Use or possession of BB handgun by minor.
Sec. 1. No person under 18 years of age shall use or possess any handgun designed and manufactured exclusively for propelling
BB’s not exceeding .177 calibre by means of spring, gas or air, outside the curtilage of his domicile unless he is accompanied
by a person over 18 years of age.
History: 1959, Act 186, Eff. Mar. 19, 1960;—Am. 1972, Act 37, Imd. Eff. Feb. 19, 1972.
752.892 Penalty.
Sec. 2. Any person who violates the provisions of this act is guilty of a misdemeanor.
History: 1959, Act 186, Eff. Mar. 19, 1960.