depends on the state whether a under 21 can be on a nfa trust or not.
if you can you can only be on it as an heir. you will not be allowed to use it unsupervised.
again it depends on your state laws.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...