Long guns are not a problem through UPS as long as the receiving FFL is agreeable. I've done this several times for warranty work back to the mfg. Only thing is you need to ship from a 'hub' location.
Handguns are usually cheaper FFL-to-FFL as long as there aren't any added fees.
Handguns are usually cheaper FFL-to-FFL as long as there aren't any added fees.