I've sold SxS's to out of state individuals and bought them from out of state - person to person, no FFL.
Just because you physically did it does not make it legal.
Correct ! And just because you got away with it "for now"-hope that the buyer does not have one of those guns stolen-or worse a backtrace if ends up in robbery/death,you might not later.
Your risking a felony-and perhaps losing your guns and right to buy guns to avoid a transfer fee that a buyer should pay anyway.
https://www.atf.gov/questions-and-answer...state-he-or-sheAn unlicensed person who is not prohibited from receiving or possessing firearms may purchase a firearm from an out–of–State source,
provided the transfer takes place through a Federal firearms licensee in his or her State of residence.
[18 U.S.C 922(a)(3) and 922(b)(3); 27 CFR 478.29]