Rome,
I don't think it's that "gray" and this discussion has been hashed out quite a few times on the C&R FFL mailing list. When I read the following, I think it's pretty clear. Found on page 119 of the green book (page 281 of the PDF).
c. Licensed Collector's Activities
Subject to other applicable provisions of the law and regulations, a
collector's license entitles its holder to transport, ship, receive and
acquire curios or relics in interstate or foreign commerce and to dispose of
curios or relics in interstate or foreign commerce to any other Federal
firearms licensee. Dispositions of curios or relics by licensed collectors
are not subject to the requirements of the Brady law; however, dispositions
should not be made to any person whom the collector knows or has reasonable
cause to believe is a felon or is within any other category of persons to whom
sales are prohibited by 18 U.S.C. 922(d).
However, ATF has recognized only assembled firearms as curios or relics.
Moreover, ATF's classification of surplus military firearms as curios or
relics has extended only to those firearms in their original military
configuration.
Frames or receivers of curios or relics are not generally recognized as
curios or relics by ATF since they are not of special interest or value as
collectors' items. Specifically, they do not meet the definition of curio or
relic in 27 CFR 178.11 as firearms of special interest to collectors by reason
of a quality other than is ordinarily associated with sporting firearms or
offensive or defensive weapons.
--
Mike
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