There is a LOT of information out there about shipping firearms... some of it is just wrong, some of it is not quite wrong.
Fedex DOES ship firearms.
Handguns MUST go overnight, and can be insured.
Long guns MAY go ground.
Note that you must ship from a FedEx depot. Authorized centers (such as FedEx Kinkos) are not allowed to accept firearms shipments. You must notify the FedEx employee that you are shipping firearms.
Please read the FedEx terms and conditions for more information.
UPS also ships firearms. The same basic rules apply.
Please read the UPS terms for shipping firearms:
USPS DOES ship firearms, but generally only FFLs may ship handguns. Unloaded rifles and shotguns may be mailed pursuant to federal, state and local laws.
Do your homework, and get the facts from the shiping company. You may find that some employees are not aware of company policy, so you may need to get a supervisor. If you have questions about shipping firearms, contact the shipping company of YOUR preference.