Check your state laws.  Federal law prohibits FFLs to transfer handguns to someone under 21. If your state allows (NC for example does with PPP) 18-20 year olds to purchase private party, there is no reason not too.

Federal Law

Exactly. Check state laws. Here's an experience i had this week in Virginia. New laws regarding and preventing private sales of firearms in Virginia have caused lots of confusion. I had a couple 18-20 year old buyers send me links to articles stating they could buy handguns in a private sale but not from an FFL. I called the Virginia State Police firearms division, and they told me yes, buyers under 21 can buy a handgun, but only at a gun show where state police do background checks without filling out the 4474 form that would automatically deny an 18 year old. So for us in Virginia, there is no more private sale and all sales have to go through FFL, with the exception of 10-20 year olds for handguns, and that is only until October 2020 when the law will change regarding that. This makes it extremely difficult to advertise and sell a firearm.
Bruce

And BATFE is pulling a fast one by aiding FFLs to initiate NICS checks in violation of Code of Federal Regulations (CFR).

FFLs have access to NICS data ONLY when performing a check under the Brady law.

The bureaucrats are running in the face of the very regulations they issued.

They do not want to initiate an actual CFR change to allow them to do what they are encouraging.
These changes typically take at least 90 days.
Thirty to 60 days of 'advertising' the change in Federal Register, then 30 days of adjudication of the comments received.
ONLY then may the change in CFR be then published again as final.

This is the Administrative Procedure Act that define how changes MUST be  done.