In my case I've been denied then had my appeal "denied" 3 times - and in each case had to go through yards or paperwork and affidavits and fingerprinting to prove I WASN"T a prohibited person.
In each case I eventually got a 'proceed' letter from the FBI. 90 ++ days after the initial decline.
After the second time I asked why they had no record of the last time I went through all this - the response was that since they destroyed all NICS records after 90 days - no record of my previous sucessful documentation and overturning of the declines was on file.
The FBI has a system in place just for people in your situation. You can set up a voluntary appeal file and get a PIN number for that file. You will giving the NICS permission to maintain the file. All you have to do is have the dealer tell the NICS that you have an appeal file and give them the PIN number. See the url and check page 8 of the attached newsletter.
http://www.atf.treas.gov/firearms/newsletter/0205fflnewsletter.pdf
Here is the text from the newletter.
The Federal Bureau of Investigation’s (FBI) NICS
Section recently sent to all Federal Firearms
Licensees (FFLs) a letter announcing a new
process that may be utilized by lawful firearms
purchasers to prevent erroneous denials or
extended delays because for example, a purchaser
may have a name or date of birth similar to that of
a prohibited person.
This process permits applicants to request that the
FBI NICS Section maintain information about
them in the Voluntary Appeal File (VAF), a
separate file to be checked by the NICS. Potential
purchasers may apply to be considered for entry
into the VAF by, among other things, signing an
applicant statement which authorizes the FBI
NICS Section to retain information that would
otherwise be destroyed upon the approval of the
firearm transaction.
At the conclusion of the FBI NICS Section’s
research, the applicant will receive a letter from the
FBI NICS Section indicating the outcome of the
research as being successful, unsuccessful, or the
information insufficient. Successful applicants will
be provided a unique personal identifier number
(UPIN), which they will provide to the FFL for all
future firearms purchases. The applicant will retain
the original letter. ATF recommends the UPIN be
placed in block 18(a) of the ATF Form 4473, along
with information about Government issued
identification documents, until such time that the
form may be revised with a block for the UPIN.
In the future, the UPIN will be provided to the Call
Center Representative during the initial background
check. In the interim, all subsequent NICS checks
on those individuals with UPINs must be
conducted through the FBI NICS Section
Customer Service at 1-877-444-6427. Select option
six from the automated menu to be transferred to a
VAF Customer Service Representative. The FFL
must state that they are conducting a NICS check
on an individual who has provided a UPIN. The
FFL will provide the UPIN to the Customer
Service Representative and the rest of the process
will remain the same.
For a copy of the FBI NICS letter or for further
information regarding the VAF, you may contact
the FBI NICS Section Customer Service at
telephone number 1-877-444-6427.