Not technically illegal for them to own the pistol, nor is it illegal for you to buy it from them. They just cannot purchase one from an LGS due to the age restriction. They can purchase through private sale or have one gifted to them.
When it comes to a holster, I don't think you should worry about adding "bling" especially if its just snakeskin wrap. Most of the kydex holsters I've purchased are a solid color, or old glory.
If you were to cover/drill through the S/N, could you have the S/N engraved elsewhere on the firearm?
My thinking is how an SBR has to have the trust engraved on the lower receiver.
This might be a better question for big brother...
Transferring between states is sort of like shipping a firearm. The firearm must be transferred in the state it will end up in. In this case a FFL in GA, even though the resident is from SC.
"May I lawfully transfer a firearm to a friend who resides in a different State? Under Federal law, an...