This sheds some light on the stance from the state of Georgia side of things:
Do you have the question, can I gift a gun for the holidays? Watch Independent Program Attorney Matt Kilgo teach what you need to know before you buy.
www.uslawshield.com
All that said, here's the deal. I gave my 22 year old daughter a Ruger LC380 for Christmas a year ago when she was 21, as a gift. I didn't sell it to her, but the principal of transfer is the same. I purchased the gun, wrapped it up, put it under the tree. She has now had it for a year. Nothing prevents her from moving to another state and taking that little pistol with her.
I don't see how its any different than my 1905 S&W M&P .38 6" revolver. It was my great grandfather's (a sheriff in the early 1900's), then my grandfather's, then my uncle's (my mother's brother), and then he gave it to me before he died, as he had no children. At some point, I will give it to my son. Not very soon I hope! Anyway, there never was or has been a bill of sale or was one required, or an FFL transfer, for that pistol that has been in the family for over a hundred years. It's never been sold, just gifted from one generation to the next. I've had it for the past 25 years.
I guess the question is whether guns are "registered" in Georgia or in Pennsylvania. I am pretty certain they are not in Georgia, at least they were not when I lived there (where my family is from). The real intent of the law is ensuring that an out of state party goes through a background check, but if it had been to an in-state individual, there would be no such requirement. If you had been a Georgia resident, purchased the gun from a family member, then left the state, there would be no issue and no FFL requirement.
Personally, I don't see how the lack of an FFL transfer on the gun you got from a relative out of state will ever come up, unless you embark on a crime spree with a 2 shot derringer. If you want to make it "right", then next time you go to Georgia, take it in the trunk in a locked case, get your relative there to go to a local FFL with you, and have them ship it to an FFL in PA.
Me? I would just put it in my gun safe, carry it, shoot it, whatever. Not even sure I would want to hold an "incriminating" bill of sale... and I will stop there.