Obama's executive orders do not revoke the definitions of a gun dealer. That creates a conflict in law. Statutory Law vs Executive Orders. If the FBI comes calling file an FOIA. That will stop the process in its tracks.
In your FOIA, ask for all the documents that classify you as a gun dealer. Having none, they have no choice but to abate enforcement.
The Executive Orders are really voluntary compliance proffers. Unlawful laws are not laws. 16 Am Jur 2d, Sec 177 late 2d, Sec 256