I've had that happen.
Idiot came in, filled out the 4473, gets denied by NICS. I give him the NTN# and instructions on how to appeal as well as the consequences of failing to appeal. Eight or none months later I check with him to confirm that he did appeal........"Uh no, FBI wouldn't tell me why, I'll reapply tomorrow". Knowing that the FBI is required by law to tell the reason for the denial within five business days I told him that a storage fee began that day.
Three months later I check in again......"Oh yeah, the FBI sent me a letter about that last month". Turns out he had been on a probationary period for a deferred adjudication when he tried to buy the gun. He had been charged with possession of marijuana or other drug and had a one year period to keep his nose clean. When that year expired, the FBI sent him the approval on his appeal. Thats why the nitwit waited so long he knew he wasn't going to get his appeal until after his period of deferred adjudication was up.
The problem is....he committed a felony the day he answered no to two of the questions on the 4473. Not wanting to get crosswise with ATF I called my IOI and asked "he committed a felony when he lied on the 4473 last March, but the FBI says I can transfer.....true?" My IOI said "The USAO does not accept those types of charges".
Right then I knew the only point of the 4473 was to bury a dealer. I charged that little snot $350 in late fees and regret not charging him more.