Importation of ammunition or ammunition components require an approved ATF Form 6 to import...
CFR
TITLE 27--ALCOHOL, TOBACCO PRODUCTS AND FIREARMS
CHAPTER I--BUREAU OF ALCOHOL, TOBACCO AND FIREARMS, DEPARTMENT OF THE TREASURY
PART 47--IMPORTATION OF ARMS, AMMUNITION AND IMPLEMENTS OF WAR
Subpart A--Scope
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(b) The permit procedures of subpart E of this part are applicable
to all importations of articles on the U.S. Munitions Import List not
subject to controls under 27 CFR Part 178 or 179. U.S. Munitions Import
List articles subject to controls under 27 CFR Part 178 or 27 CFR Part
179 are subject to the import permit procedures of those regulations if
imported into the United States (within the meaning of 27 CFR Parts 178
and 179).
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Subpart C--The U.S. Munitions Import List
Sec. 47.21 The U.S. Munitions Import List.
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category iii--ammunition
(a) Ammunition for the arms in Categories I and II of this section.
(b) Components, parts, accessories, and attachments for articles in
paragraph (a) of this category, including but not limited to cartridge
cases, powder bags, bullets, jackets, cores, shells (excluding shotgun
shells), projectiles, boosters, fuzes and components therefor, primers,
and other detonating devices for such ammunition.
(c) Ammunition belting and linking machines.
(d) Ammunition manufacturing machines and ammunition loading
machines (except handloading ones).
Note: Cartridge and shell casings are included under Category III
unless, prior to their importation, they have been rendered useless
beyond the possibility of restoration for use as a cartridge or shell
casing by means of heating, flame treatment, mangling, crushing,
cutting, or popping.