By the time you turn 21 the paperwork will still be in the process mode.
Here's the atf contact info
Get who you talked with this way if there is a problem down the road you already have verbal documentation (so to speak) with ATf contact info.
Name
date
Time

They have a fairly decent turn around response time.


If you have any questions relating to NFA, please contact the ATF National Firearms Act Branch.
Bureau of Alcohol, Tobacco, Firearms and Explosives
National Firearms Act Branch

244 Needy Road
Martinsburg, West Virginia 25405 USA
Voice (304) 616-4500
Fax (304) 616-4501