A Juvenile by defenition is a person under 18years of age and that does not apply to you.
A Juvenile (under 18years of age) may even sell guns at a gun shop with written permission from parents or legal guardian.
(B14) May a parent or guardian purchase firearms or ammunition as a gift for a juvenile (less than 18 years of age)? [Back]
Yes. However, possession of handguns by juveniles (less than 18 years of age) is generally unlawful. Juveniles generally may only receive and possess handguns with the written permission of a parent or guardian for limited purposes, e.g., employment, ranching, farming, target practice or hunting.
(F4) May an employee of a licensed dealer, such as a manager or clerk, who is under 21 years of age, sell handguns and ammunition suitable for use in handguns for the licensee? [Back]
Yes, if the employee is not a prohibited person (e.g., a felon). However, to sell handguns, a person less than 18 years of age must have the prior written consent of a parent or guardian and the written consent must be in the person’s possession at all times. Also, the parent or guardian giving the written consent may not be prohibited by law from possessing a firearm. Moreover, State law must not prohibit the juvenile from possessing the handguns or ammunition.
You must remember the key word is JUVENILE. Under the age of 18. Your original problem was age 21. You are 19 a free to fondle all the handguns you want. Unless state law superseeds federal law.