If for some reason the ATF or FBI traces a gun to you...
...It might save you a few hours worth of questioning if nothing else...
If the FBI / local cops actually follow the law and the Constitution
they shouldn't be arresting you and interrogating you unless they already have probable cause that you've committed a crime.
They shouldn't be searching your home w/o your permission unless a judge has signed a search warrant based on probable cause that the crime gun will be found there. The warrant should, in theory, only be valid if it is based on recent credible information - not "stale" information that several years ago you bought a gun from a gun dealer and no information about what's happened to it since then,
and knowing that Georgia is a state where guns are freely sold & traded without anybody updating the government records about that gun's current location.
Now if cops ask, rather than demanding, that you voluntarily do a Q&A session about some gun that you used to own, remember it's voluntary! You can say NO.
Or you could you but initially agree but not let it go on too long; you may end the interview at any time.