Here are the relevant regs:
§ 178.40a Transfer and possession of large capacity ammunition feeding
devices.
(a) Prohibition. No person shall transfer or possess a large
capacity ammunition feeding device.
(b) Exceptions. The provisions of paragraph (a) of this section
shall not apply to:
(1) The possession or transfer of any large capacity ammunition
feeding device otherwise lawfully possessed on September 13, 1994;
(2) The manufacture for, transfer to, or possession by the United
States or a department or agency of the United States or a State or a
department, agency, or political subdivision of a State, or a transfer to
or possession by a law enforcement officer employed by such an entity for
purposes of law enforcement;
(3) The transfer to a licensee under title I of the Atomic Energy Act
of 1954 for purposes of establishing and maintaining an on-site physical
protection system and security organization required by Federal law, or
possession by an employee or contractor of such licensee on-site for such
purposes or off-site for purposes of licensee-authorized training or
transportation of nuclear materials;
(4) The possession, by an individual who is retired from service with
a law enforcement agency and is not otherwise prohibited from receiving
ammunition, of a large capacity ammunition feeding device transferred to
the individual by the agency upon such retirement;
(5) The manufacture, transfer, or possession of any large capacity
ammunition feeding device by a manufacturer or importer for the purpose of
testing or experimentation in accordance with § 178.153; or
(6) The manufacture, transfer, or possession of any large capacity
ammunition feeding device by a manufacturer or importer for the purpose of
exportation in accordance with the Arms Export Control Act (22 U.S.C.
2778).
(c) Importation, manufacture, and dealing in large capacity
ammunition feeding devices. Possession and transfer of large capacity
ammunition feeding devices by persons who manufacture, import, or deal in
such devices will be presumed to be lawful if such persons maintain
evidence establishing that the devices are possessed and transferred for
sale to purchasers specified in paragraph (b) of this section. Examples
of acceptable evidence include the following:
(1) Contracts between persons who import or manufacture such devices
and persons who deal in such devices stating that the devices may only be
sold to law enforcement agencies or other purchasers specified in
paragraph (b) of this section;
(2) Copies of purchase orders submitted to persons who manufacture,
import, or deal in such devices by law enforcement agencies or other
purchasers specified in paragraph (b) of this section;
(3) Copies of letters submitted to persons who manufacture, import,
or deal in such devices by government agencies or other purchasers
specified in paragraph (b) of this section expressing an interest in
purchasing the devices;
(4) Letters from persons who deal in such devices to persons who
import or manufacture such devices stating that sales will only be made to
law enforcement agencies or other purchasers specified in paragraph (b) of
this section; and
(5) Letters from law enforcement officers purchasing in accordance
with paragraph (b)(2) of this section and § 178.132.
(Paragraph (c) approved by the Office of Management and Budget under
control number 1512-0526)
[T.D. ATF-363, 60 FR 17452, Apr. 6, 1995, as amended by T.D. ATF-383, 61
FR 39321, July 29, 1996]
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Mike