The law doesn’t say one can, it simply does not say one cannot. ‘Nulla poena sine lege’ is the legal concept of ‘no penalty without a law” essentially meaning that everything that is not expressly forbidden is allowed. Laws either say that: (A) a person may or shall do something, (B) a person shall not, or (C) the law is silent. In this case, the law doesn’t say much anything about persons in the 18-20 year old age range and firearms.
ARS 13-3102 states a person must be at least twenty-one years old to conceal a deadly weapon like a firearm, and also includes certain exceptions, like if they are on property they lease or own, or that their parents or grandparents lease or own.
ARS 13-3111 imposes certain restrictions and exceptions on minors (age 17 and lower), from carrying or possessing. Also notice it’s not an outright ban and contains exceptions for hunting and sport shooting at ranges and the likes.
ARS 13-3101 defines who a prohibited person is. Age is not a factor in this definition, it only mentions factors like being a convicted felon, or a fugitive, etc.
Given the law says a person must be 21 to conceal, and those under 18 have certain restrictions: it’s concluded that those who are 18-20 can legally open carry and possess a handgun, provided they are not otherwise a prohibited posesssor.
Furthermore, on purchasing firearms, Arizona state law only regulates sales and gifts to minors in 13-3109. It’s not an outright ban, but there are some restrictions, namely you need written parental permission, with a few exceptions for coaches and instructors.
Federal law prohibits those with an FFL from selling handguns or handgun ammo to those under the age of 21.
“Q: Does a customer have to be a certain age to buy firearms or ammunition from a licensee?
ATF.gov Website
Yes. Under the GCA, long guns and long gun ammunition may be sold only to persons 18 years of age or older. Sales of handguns and ammunition for handguns are limited to persons 21 years of age and older. Although some State and local ordinances have lower age requirements, dealers are bound by the minimum age requirements established by the GCA. If State law or local ordinances establish a higher minimum age, the dealer must observe the higher age requirement.
[18 U.S.C. 922(b)(1), 27 CFR 478.99(b)]”
If one is not an FFL holder, and is otherwise allowed to own firearms, a resident of AZ can sell a handgun or other firearm to any resident of Arizona who is 18 years of age or older and whom they don’t believe to be a prohibited possessor, or any resident Arizona under 18 whom they have written parental permission and whom they don’t believe to be a prohibited possessor.
*This is provided as a Legal Information Resource and should not be treated as legal advice.