You have to go to a UPS terminal near you to ship a firearm. YOu cannot go to a UPS store. THrow a copy of the FFL in the box with the gun and show the clerk the FFL if absolutely needed. No need to tell him what is in the box, if he asks be honest .
If the shipper is NOT an FFL he should not have a copy of the FFL, period. BATFE does not want FFLs to give copies to anyone except other FFLs. There is no duty to show UPS a FFL copy, period!