Here it is, straight from the horses mouth (UPS website):
Shipping Firearms
Special Procedures for Shipping Firearms
Use These UPS Services for Your Firearm Shipment
UPS accepts packages containing firearms, as defined by Title 18, Chapter 44, and Title 26, Chapter 53 of the United States Code, for transportation from and between licensed importers, licensed manufacturers, licensed dealers, and licensed collectors, as defined in Title 18, Chapter 44 of the United States Code, law enforcement agencies of the United States (or of any department or agency of the United States) and law enforcement agencies of any state or department agency (or political subdivision of any state), and from and between persons not otherwise prohibited from shipping firearms by federal, state or local law and when such shipment complies with all applicable federal, state and local laws applicable to the shipper, recipient and package.
Handguns, as defined by 18 U.S.C. § 921,will be accepted for transportation only via UPS Next Day Air® Early A.M.®, UPS Next Day Air®, or UPS Next Day Air Saver® services. (Note: UPS Express CriticalSM Service is not available for firearms).
UPS accepts firearm parts for shipment, provided the part is not a "firearm" as defined under federal law; the contents of the package cannot be assembled to form a firearm; and the package otherwise complies with federal, state, and local law. (Note: Receivers or frames of a firearm, firearm mufflers and silencers are considered "firearms" and are accepted for transportation only if shipped in accordance with UPS's requirements for shipping firearms.)
UPS does not accept automatic weapons, including machine guns, for shipment.
Firearms, including handguns, and firearm parts are not accepted for shipment internationally
Ammunition may be accepted for shipment internationally provided it is shipped in accordance with the UPS Guide for Shipping International Goods.
UPS ReturnsSM Services are not available for packages containing firearms.
Follow These Packing Requirements
Packages containing handguns must be separated from other packages being delivered to UPS.
Ammunition cannot be included in packages that contain firearms (including handguns). Ammunition must be shipped in accordance with the UPS Guide for Shipping Ground and Air Hazardous Materials, or the UPS Guide for Shipping International Dangerous Goods.
Small arms ammunition, as defined in 49 C.F.R. § 173.59, will be transported only when packaged and labeled in compliance with 49 C.F.R. § 172 regarding hazardous materials shipments.
About Documentation and Labeling
The shipper must use Delivery Confirmation Adult Signature Required service for each package containing a firearm, including a handgun, and affix a UPS label requesting an adult signature upon delivery.
Getting Your Firearm Shipment to UPS
You can only ship your package that contains a handgun from UPS daily pickup accounts or through UPS Customer Centers (counters at UPS operational facilities). Note: Handguns are not accepted for shipment through UPS Internet Shipping, UPS Drop Boxes, or UPS On-Call PickupSM, or at The UPS Store® or any third party retailer.
When you are shipping a package that contains a handgun, you must verbally notify the UPS driver or UPS Customer Center clerk.
You can ship a firearm (excluding handguns), from a UPS daily pickup account, UPS On-Call Pickup, One-Time Pickup, or a UPS Customer Center. Note: Firearms are not accepted for shipment through UPS Internet Shipping, UPS Drop Boxes, or at The UPS Store or any third party retailer.
See the terms and conditions in the UPS Tariff/Terms and Conditions of Service for information regarding firearm shipments.
Theres a lot on the BATF website too but I didn't have anough room to copy and paste it!
