Firearms are permitted in checked luggage, but they must be declared at the United Air Line's ticket counter during check-in. All firearms must be in unloaded and stored in a locked hard-sided container. The lock must be one that can only be opened by the gun owner; common luggage locks that can be easily opened if pressure is applied do not qualify.
Up to 11 lbs. of small arms ammunition is permitted in checked luggage. Ammunition must be securely packed in wood, metal or fiber boxes, or other packaging specifically designed for ammunition. Ammunition may be kept in the same case as the firearm so long as it is packed according to regulations. Firearm magazines or clips are not permitted for packing ammunition unless they securely and completely enclose the ammunition.
Flares and gun powder, including black powder and percussion caps, are never permitted in checked or carry-on luggage. Flare guns are permitted in checked luggage if they are stored following firearm regulations.
Regulations for bringing firearms on international flights vary depending on the destination country. It is suggested that passengers traveling on international flights check with the authorities in the destination country regarding firearm regulations.