Bad advice. How do you plan to get the gun back?
People constantly give this advice or pawning it. They don't have a clue what they're talking about and the legal aspects of it.
If you leave a firearm at a gun shop then the dealer has to be entered into their books. If he has firearms in his shop that are not in his books and is inspected by ATF he's in a lot of legal trouble. FFL dealers know this. When you return that dealer cannot legally let you have the gun back since you are an out of state resident. To get your gun returned the gun shop will have to ship it to an FFL in your home state and you can pick it up from the FFL at home. After you pay the FFL fees for both dealers.
Where is this in federal/state law? If there is no "sale" involved does it fall under a different category?