You're making the common error of confusing citizenship with residence...
An american RESIDENT can leave the US with 1000 rounds for personal use without any paperwork. And his post spoke only about the Canadian import regulations leading the rest of us to reasonably conclude that he was unaware of the USATF export regs.
Your right.
"123. 17(c) Temporary export of firearms and ammunition for personal use -
U.S. persons may export temporarily not more than three non-automatic firearms and not more than 1,000 cartridges of ammunition provided that this is for the person's exclusive use and not for re-export or other transfer of ownership (i.e., firearms for use on hunting trips)."
US Persons is defined as:
" U.S. person means a person (as defined in § 120.14 of this part) who is a protected individual as defined by 8 U.S.C. 1324b(a)(3). It also means any corporation, business association, partnership, society, trust or any other entity, organization or group that is incorporated to do business in the United States. It also includes any governmental (federal, state or local) entity. It does not include any foreign person as defined in § 120.16 of this part."
8 U.S.C. 1324b(a)(3) defines a protected indiviudal as
"(3) “Protected individual” defined
As used in paragraph (1), the term “protected individual” means an individual who—
(A) is a citizen or national of the United States, or
(B) is an alien who is lawfully admitted for permanent residence, is granted the status of an alien lawfully admitted for temporary residence under section 1160 (a) or 1255a (a)(1) of this title, is admitted as a refugee under section 1157 of this title, or is granted asylum under section 1158 of this title; but does not include
(i) an alien who fails to apply for naturalization within six months of the date the alien first becomes eligible (by virtue of period of lawful permanent residence) to apply for naturalization or, if later, within six months after November 6, 1986, and
(ii) an alien who has applied on a timely basis, but has not been naturalized as a citizen within 2 years after the date of the application, unless the alien can establish that the alien is actively pursuing naturalization, except that time consumed in the Service’s processing the application shall not be counted toward the 2-year period"
Back on topic, I will be buying a FiveSeven shortly. I'm told it's a cool little gun. I need something for body armoured zombies
