Got to be 21 to own a weapon? How's that work?
"(a) The militia of the United States consists of all able-bodied males at least 17 years of age and, except as provided in section 313 of title 32 , under 45 years of age who are, or who have made a declaration of intention to become, citizens of the United States and of female citizens of the United States who are members of the National Guard.
US Code, Title 10, 311
Unfortunately I don't think that will help
Other wise we would have the 18/21 long gun/handgun rules now.