This can be done legally. Here is a good bit of information from AOPA:
Transporting Firearms in General Aviation Aircraft
Occasionally, AOPA gets questions from our members asking whether or not they can carry firearms with them in their general aviation aircraft. The answer varies depending on the circumstances. This report was written to provide guidance on the transporting of firearms in a general aviation aircraft, whether the transporter would fall under federal or state jurisdiction, and what the laws are when crossing the U.S. border in any direction.
The transportation of any firearm, while allowed by the federal government as part of the citizen constitutional right to bear arms, does have limitations, some restrictions, and certain regulatory requirements.
Overview of the regulations
The U.S. Treasury Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) controls these regulations. First of all, all military weapons or military style/type firearms are prohibited. However, certain firearms are acceptable and suitable for sporting, hunting, and general transportation. The Federal Firearms Regulations Reference Guide details the Gun Control Act, the National Firearms Act, the Arms Export Control Act, and all relevant regulations and rulings. Title 27 CFR of the ATF Regulations describes the importation of arms, ammunition, and implements of war; commerce in firearms and ammunition; and much more. If you want to import or export weapons or ammunition, you must do so through a licensed importer, dealer, or manufacturer. Also, if the National Firearms Act prohibits certain weapons, ammunition, or similar devices from coming into the country, you will not be able to import them unless the ATF provides you with written authorization to do so.
Carrying a concealed firearm on an airport
The regulations that apply to carrying a concealed firearm on an airport or into an FBO fall under the jurisdiction of either federal or state government, depending on where you are on airport property. Federal law on firearms possession applies to the so-called "sterile" area (the area beyond the metal detectors) of passenger terminals. Read the Transportation Security Administration's (TSA's) page on Traveling with Firearms and Ammunition and check Transportation Security Regulations Part 1542 "Airport Security" (formerly FAA Part 107) for more details. Possession of firearms outside the "sterile" area (e.g., at the FBO or airport vehicle parking lot) is governed by state law.
In the case of concealed firearms, remember that many states have a provision in their laws that allows the owner of a business to prohibit customers from carrying concealed firearms if a notice is posted to that effect at the entrance to the business. If you violate the owner's wishes, you've violated state law.
The federal safe passage provision
The federal statute that has some applicability here is 18 USC 926A, Interstate Transportation of Firearms, known as the Federal Safe Passage Act. This law provides that anyone who is not prohibited from possessing firearms under federal law (those prohibited include felons, the dishonorably discharged, etc.) may transport firearms from any place where they can lawfully possess and carry such firearms to any other place where they can lawfully possess and carry such firearms. If you can lawfully possess and carry a firearm in both Pennsylvania and Florida, then you can lawfully travel through any state in which you cannot lawfully possess and carry a firearm while on your way from Pennsylvania to Florida. In order to qualify for the federal protection afforded by the act, you have to comply with a few requirements such as unloading and storing the firearm. Here is what 18 USC 926A, Interstate Transportation of Firearms, states:
"Notwithstanding any other provision of any law or any rule or regulation of a State or any political subdivision thereof, any person who is not otherwise prohibited by this chapter from transporting, shipping, or receiving a firearm shall be entitled to transport a firearm for any lawful purpose from any place where he may lawfully possess and carry such firearm to any other place where he may lawfully possess and carry such firearm if, during such transportation the firearm is unloaded, and neither the firearm nor any ammunition being transported is readily accessible or is directly accessible from the passenger compartment of such transporting vehicle: Provided, That in the case of a vehicle without a compartment separate from the driver's compartment the firearm or ammunition shall be contained in a locked container other than the glove compartment or console."
Disclaimer: The preceding was not intended as legal advice and should not be taken as such. It is recommended that you contact an attorney in your state who specializes in this area of the law.
States and local governments
Individual states, local communities, municipalities, and counties may have their own specific regulations. At the state level, many states have a requirement to register and obtain a special permit to carry small firearms such as pistols. Any private pilot desiring to transport a firearm, weapon, or similar device must review the appropriate regulations and should contact the local airport management or law enforcement authorities for approval to land at any airport if any firearm is on board. Further, even if a permit has been obtained to carry a small firearm in one state, it does not mean other states have to accept this permit by reciprocity.
Title 49 CFR, Department of Transportation Hazardous Material Regulations Part 172.101, governs the transportation, packing, and labeling of ammunition. It is best not to travel with ammunition but rather to purchase it at your destination. However, if ammunition must be transported, travel with only the amount needed for the sporting or hunting event.
Firearms carried as part of any survival gear, kit, or equipment are subject to the same requirements stated above. However, flare guns, canisters, cartridges, or other types of signaling devices are not considered firearms and are regulated by Department of Transportation Title 49 CFR Hazardous Material Regulations.
When traveling to Canada on sporting or hunting trips, prior permission to enter that country must be obtained. Both U.S. Customs and Canadian Customs must be contacted to obtain prior permission for entry. Register the firearm prior to leaving the United States as suggested by the ATF below. Also contact the Canada Department of Justice for import approval.
Any firearm to be imported into Canada must be declared to Canada Customs upon entry arrival and a prior permit is required. Prior to leaving the U.S. the firearm must be registered with U.S. Customs to make certain returning into the U.S. will not be a problem. Review the information on Importing a Firearm or Weapon Into Canada and from the Canada Firearms Centre for details on the Canada permit application process.
As a general guideline, taking firearms into Mexico is not recommended because of the risk of major problems or delays to your trip. This is because, although prior permission must be obtained from the Mexico secretary of Environmental and Natural Resources at the Customs airport of entry upon arrival, the procedure for doing this is not clear or documented. If contact is made prior to departure with a U.S. office of the Mexico Consulate, they may be able to assist. A minimum process time of 45 days should be expected when completing the documents for approval. The consulate might also advise what firearms are and are not permitted.
Canada and Mexico are specifically listed above, but other countries will not allow you to enter with a firearm even if you are only traveling through the country on the way to your final destination. If you plan to take your firearms or ammunition to another country, you should contact officials at that country's embassy or consulate to learn about its regulations.
Purchase of firearms internationally
Any firearm purchased outside of the United States that has not been registered by the owner MUST NOT BE IMPORTED INTO THE UNITED STATES until the proper ATF import permit (ATF Form 6) has been obtained. For further information about importing any firearm, contact the Bureau of Alcohol, Tobacco, Firearms and Explosives, U.S. Department of Justice, Washington, D.C. 20226; or call 202/927-8320.
Foreign nationals living and working in the United States must be aware of the ATF requirements and comply accordingly. Any foreign national visiting, or for whatever reason only in the U.S. temporarily, must comply. The process for aliens bringing firearms into the United States is outlined below and in the supporting links.
New requirements for import permits for nonimmigrant aliens bringing firearms and ammunition into the United States
The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and the U.S. Customs Service announce new regulations affecting the purchase, possession, and importation of firearms and ammunition by nonimmigrant aliens entering the United States. The rules serve to implement the provisions of Public Law 105-277, passed by Congress in 1998 to amend the Gun Control Act of 1968.
Among other provisions relating to domestic sales of firearms and ammunition, the new regulations require nonimmigrant aliens who bring firearms or ammunition into the United States for hunting or sporting purposes to obtain an approved import permit from ATF prior to entering the United States. The regulations became effective February 19, 2002.
In order to obtain an import permit, a nonimmigrant alien must file an ATF Form 6. An interactive, electronic version of the form is currently available on the ATF Web site.
The form is also available from any ATF field office and the ATF Imports Branch (650 Massachusetts Avenue N.W., Washington, D.C. 20226). General information and filing instructions are included with each form. A nonimmigrant alien applying for an import permit must submit the Form 6 accompanied by documentation (such as a valid hunting license or permit lawfully issued in the United States or an invitation to a shooting match) that establishes that he falls within an exception to the general prohibition on nonimmigrant aliens possessing or receiving firearms or ammunition.
Upon receiving the Form 6, ATF's Firearms Import Branch in Washington, D.C., examines it and either approves the permit application or denies it. If the contemplated importation is approved, the permit is valid for 12 months from the date of approval. ATF then returns the approved permit and attached documentation to the applicant, along with a restriction stating that the specified firearm or ammunition must be taken out of the United States when the individual leaves this country.
The ATF Form 6 and any other necessary documents must then be presented to Customs at the time of entry into the United States. The Customs officer handling the importation will determine whether the entry is in order and will then allow the nonimmigrant alien to bring the firearms into the United States.
The ATF Web site has a detailed section of frequently asked questions for nonimmigrant aliens regarding firearms and ammunition.
You do not need an ATF permit if you can demonstrate that you are returning with the same firearms or ammunition that you took out of the United States. To prevent problems when returning, you should register your firearms and related equipment by taking them to any CBP office before you leave the United States. The CBP officer will register them on the same CBP Form 4457 used to register cameras or computers.
Updated Monday, November 24, 2008