Who's game are you playing? Arguing the finer points of the law is going to cost you $400+ an hour for your lawyer to do with you in court. Theres a list of ATF rulings. Theres some oldies but goodies in there. Open bolt being machine guns, Auto sear being a machine gun by itself etc. Those "Rulings" can be ignored too if you feel like it because they arent "laws". Go for it.
https://www.atf.gov/rules-and-regulations/firearms-rulings
The ATF-NFA publishes a handbook. It is in your best interest to use their guidelines and "Rulings" when you build and adhere to those guidelines. 2002-6 is an ATF ruling. Ignore ATF rulings all you like. "Conspicuously" as noted in 27 CFR 178.92 is defined in the 2002-06 ruling.
From
RULING 2002-06
"In accordance with 27 CFR 178.92 and 27 CFR 179.102, identification of
firearms, armor piercing ammunition, and large capacity ammunition feeding
devices, the terms "conspicuously" and "legibly" as used therein mean,
respectively, that the markings are wholly unobstructed from plain view and
that the markings contain exclusively Roman letters and Arabic numerals"
"The above regulations require markings that legibly identify each item
or package and require that such markings are conspicuous. ATF has
consistently taken the position that "legibly" marked means using exclusively
Roman letters (A, a, B, b, C, c, and so forth) and Arabic numerals (1, 2, 3,
4, 5, 6, and so forth), and
"conspicuous" means that all required markings
must be placed in such a manner as to be wholly unobstructed from plain
view. "
"Similarly, firearms and large capacity ammunition feeding devices
which contain required markings obstructed in whole or in part from plain
view must be remarked with required markings that satisfy the
conspicuousness requirements described above.
For example, required
markings may not be placed on a portion of the barrel where the markings
would be wholly or partially obstructed from view by another part of the
firearm, such as a flash suppressor or bayonet mount."
§ 178.92 Identification of firearms,
armor piercing ammunition, and
large capacity ammunition feeding
devices.
(a)(1) Firearms. Each licensed manufacturer
or licensed importer of any
firearm manufactured or imported
shall legibly identify each such firearm
by engraving, casting, stamping (impressing),
or otherwise conspicuously
placing or causing to be engraved, cast,
stamped (impressed) or placed on the
frame or receiver thereof in a manner
not susceptible of being readily obliterated,
altered, or removed, an individual
serial number not duplicating any serial
number placed by the manufacturer
or importer on any other firearm,
and by engraving, casting, stamping
(impressing), or otherwise conspicuously
placing or causing to be engraved,
cast, stamped (impressed) or
placed on the frame, receiver, or barrel
thereof in a manner not susceptible of
being readily obliterated, altered or removed,
the model, if such designation
has been made; the caliber or gauge;
the name (or recognized abbreviation
of same) of the manufacturer and also,
when applicable, of the importer; in the
case of a domestically made firearm,
the city and State (or recognized abbreviation
thereof) wherein the licensed
manufacturer maintains its
place of business; and in the case of an
imported firearm, the name of the
country in which manufactured and
the city and State (or recognized a
As far as Bullpups go...
(3) Exceptions—(i) Alternate means of
identification. The Director may authorize
other means of identification of
the licensed manufacturer or licensed
importer upon receipt of a letter application,
in duplicate, showing that such
other identification is reasonable and
will not hinder the effective administration
of this part.
