Exporting firearms and ammunition from the U.S. normally requires a license--from the State Department for rifles, handguns, and rifle or handgun ammunition, and from the Commerce Department for shotguns and shotshells. But for many years, the State Department’s International Trafficking in Arms Regulations (ITAR) have allowed Americans to temporarily export up to three non-automatic firearms and up to 1,000 rounds of ammunition without a permit, as long as the firearms were declared and presented to a Customs officer. This was done by bringing the firearms to a Customs office at some point before the trip and completing Customs Form 4457--a form that can be completed for any personal property and that is normally used to prove that the traveler owned the property before going abroad, thus protecting the traveler from paying import duties on items already owned. The traveler would retain the form and present it upon reentry if needed.
But a 2012 State Department rule change added an important new requirement that the traveler declare rifles or handguns “upon each departure” by presenting documentation generated through the Commerce Department’s “Automated Export System” (AES)--an online reporting tool designed for use by businesses. (Non-“combat” shotguns are not regulated by the State Department, so the AES requirement does not apply to temporary shotgun exports.) The rule change was buried in a Federal Register notice aimed at authorizing the temporary export of gas masks by government employees and contractors.
Fortunately, the change was never enforced—until now. In postings on the Immigration and Customs Enforcement (ICE) website and in internal ICE documents obtained by NRA-ILA, ICE makes clear that it has begun enforcing the rule change. Form 4457 may no longer be used for firearms, and electronic declarations will be the norm.
The solution turned out to be gun registration:
To establish such proof, a bill of sale, receipt, copy of ATF Form 4473, household effects inventory, packing list, or registration on Customs Forms 4457 or 4455 may be used, if the registration form is completed prior to departure from the U.S.
This means if you leave the country with a gun and do not have it when you return (because the gun was lost, or you returned it by some other method than bringing it with you), you may well find yourself charged with unauthorized export of arms. Furthermore, this registration may violate a provision of the Firearms Owners Protection Act of 1986:
(a) The Attorney General may prescribe only such rules and regulations as are necessary to carry out the provisions of this chapter, including—
(1) regulations providing that a person licensed under this chapter, when dealing with another person so licensed, shall provide such other licensed person a certified copy of this license;(2) regulations providing for the issuance, at a reasonable cost, to a person licensed under this chapter, of certified copies of his license for use as provided under regulations issued under paragraph (1) of this subsection; and(3) regulations providing for effective receipt and secure storage of firearms relinquished by or seized from persons described in subsection (d)(8) or (g)(8) of section 922. No such rule or regulation prescribed after the date of the enactment of the Firearms Owners’ Protection Act may require that records required to be maintained under this chapter or any portion of the contents of such records, be recorded at or transferred to a facility owned, managed, or controlled by the United States or any State or any political subdivision thereof, nor that any system of registration of firearms, firearms owners, or firearms transactions or dispositions be established. Nothing in this section expands or restricts the Secretary’s  authority to inquire into the disposition of any firearm in the course of a criminal investigation.