Bigbulls is correct about everything except one....you DO NOT have to ship a handgun overnight. More urban legend.

Last time I shipped a revolver to Smith & Wesson I shipped it UPS regular ground and did not ship overnight.

UPS may have a rule asking for overnight shipping and might void insurance if you do not ship overnight but there is no gov't regulation for overnight shipping.

TITLE 27--ALCOHOL, TOBACCO PRODUCTS, AND FIREARMS

CHAPTER II--BUREAU OF ALCOHOL, TOBACCO, FIREARMS, AND EXPLOSIVES,
DEPARTMENT OF JUSTICE

PART 478_COMMERCE IN FIREARMS AND AMMUNITION--Table of Contents

Subpart C_Administrative and Miscellaneous Provisions

Sec. 478.31 Delivery by common or contract carrier.

(a) No person shall knowingly deliver or cause to be delivered to
any common or contract carrier for transportation or shipment in
interstate or foreign commerce to any person other than a licensed
importer, licensed manufacturer, licensed dealer, or licensed collector,
any package or other container in which there is any firearm or
ammunition without written notice to the carrier that such firearm or
ammunition is being transported or shipped: Provided, That any passenger
who owns or legally possesses a firearm or ammunition being transported
aboard any common or contract carrier for movement with the passenger in
interstate or foreign commerce may deliver said firearm or ammunition
into the custody of the pilot, captain, conductor or operator of such
common or contract carrier for the duration of that trip without
violating any provision of this part.
(b) No common or contract carrier shall require or cause any label,
tag, or other written notice to be placed on the outside of any package,
luggage, or other container indicating that such package, luggage, or
other container contains a firearm.
(c) No common or contract carrier shall transport or deliver in
interstate or foreign commerce any firearm or ammunition with knowledge
or reasonable cause to believe that the shipment, transportation, or
receipt thereof would be in violation of any provision of this part:
Provided, however, That the provisions of this paragraph shall not apply
in respect to the transportation of firearms or ammunition in in-bond
shipment under Customs laws and regulations.
(d) No common or contract carrier shall knowingly deliver in
interstate or foreign commerce any firearm without obtaining written
acknowledgement of receipt from the recipient of the package or other
container in which there is a firearm: Provided, That this paragraph
shall not apply with respect to the return of a firearm to a passenger
who places firearms in the carrier's custody for the duration of the
trip.

[33 FR 18555, Dec. 14, 1968. Redesignated at 40 FR 16385, Apr. 15, 1975,
and amended by T.D. ATF-354, 59 FR 7112, Feb. 14, 1994; T.D. ATF-361, 60
FR 10786, Feb. 27, 1995]