The US does not have a gun show exception. All dealers must do the same background check and paperwork that they do in stores, and the dealers will also do this

The US does not have a gun show exception. All dealers must do the same background check and paperwork that they do in stores, and the dealers will also do this for any individual buyer & seller who ask. Some private sellers (a minority, in my experience) don't insist on having a dealer do the transfer, but that has nothing to do with where the sake takes place.