Federal law requires that you be 21 years or age or older to purchase a stripped receiver or frame. If a frame or receiver can only be made into a long gun (rifle or shotgun), it is still a frame or receiver not a handgun or long gun. However, they still are “firearms” by definition, and subject to the same GCA limitations as any other firearms. See Section 921(a)(3)(b). 18 U.S.C. Section 922(b)(1) makes it unlawful for a licensee to sell any firearm other than a shotgun or rifle to any person under the age of 21.