First, tell your niece "Semper Fi" from a former active duty Marine.
The transfer must go through a FFL. So your choices are to buy the gun and present it to her, which would be quite a gesture. Then take her to the FFL and transfer it to her.
The other option is to maybe give your niece a gift certificate for the firearm. This is pretty much what a group of fellow workers did for my years ago on my 30th birthday. I ended up with a Beretta 92FS
