I just sent an XP-100 from Oregon to Minnesota via FedEX. I had a copy of the recipients FFL and that was all I needed. It had to go overnight, but I have heard of situations where if the gun is 'deactivated', as in a T/C frame only with no barrel, a revolver without a cylinder, or maybe even an XP without a bolt, can be shipped ground. If this is true, two packages going ground is cheaper than one going overnight.
Larry