FWIW, that reads more like a rule for employees rather than one for someone walking in from the street. If there isn't a law against it (and I'm taking no stance on that, one way or the other), then I would think that the PO saying "No Guns!" would only have effect in a state where there was a law compelling you to follow such signs.
It seems like it's LEGAL to carry on postal property.... 930 (d)(a)3
Possessing a firearm or other dangerous weapon in a federal facility for other than official purposes, causing such a weapon to be present, or attempting to do so are punishable by a fine, imprisonment for up to 1 year, or both. If the prohibited weapon is intended to be used to commit a crime, the penalty is an increased fine, imprisonment for up to 5 years, or both. See Title 18,
United States Code, Section 930.
§ 930. Possession of firearms and dangerous
weapons in Federal facilities
(a)
Except as provided in subsection
(d),
whoever
knowingly possesses or causes to be present
a firearm or other dangerous weapon in a Federal
facility (other than a Federal court facility),
or attempts to do so, shall be fined under
this title or imprisoned not more than 1 year, or
both.
(b) Whoever, with intent that a firearm or
other dangerous weapon be used in the commission
of a crime, knowingly possesses or causes
to be present such firearm or dangerous weapon
in a Federal facility, or attempts to do so, shall
be fined under this title or imprisoned not more
than 5 years, or both.
(c) A person who kills any person in the course
of a violation of subsection (a) or (b), or in the
course of an attack on a Federal facility involving
the use of a firearm or other dangerous
weapon, or attempts or conspires to do such an
act, shall be punished as provided in sections
1111, 1112, 1113, and 1117.
(d) Subsection (a) shall not apply to—
(1) the lawful performance of official duties
by an officer, agent, or employee of the United
States, a State, or a political subdivision
thereof, who is authorized by law to engage in
or supervise the prevention, detection, investigation,
or prosecution of any violation of
law;
(2) the possession of a firearm or other dangerous
weapon by a Federal official or a member
of the Armed Forces if such possession is
authorized by law; or
(3) the lawful carrying of firearms or other
dangerous weapons in a Federal facility incident
to hunting or other lawful purposes.
(e)(1) Except as provided in paragraph (2), whoever
knowingly possesses or causes to be present
a firearm or other dangerous weapon in a Federal
court facility, or attempts to do so, shall be
fined under this title, imprisoned not more than
2 years, or both.
(2) Paragraph (1) shall not apply to conduct
which is described in paragraph (1) or (2) of subsection
(d).
(f) Nothing in this section limits the power of
a court of the United States to punish for contempt
or to promulgate rules or orders regulating,
restricting, or prohibiting the possession
of weapons within any building housing such
court or any of its proceedings, or upon any
grounds appurtenant to such building.
(g) As used in this section:
(1) The term ‘‘Federal facility’’ means a
building or part thereof owned or leased by the
Federal Government, where Federal employees
are regularly present for the purpose of performing
their official duties.
(2) The term ‘‘dangerous weapon’’ means a
weapon, device, instrument, material, or substance,
animate or inanimate, that is used for,
or is readily capable of, causing death or serious
bodily injury, except that such term does
not include a pocket knife with a blade of less
than 21⁄2 inches in length.
(3) The term ‘‘Federal court facility’’ means
the courtroom, judges’ chambers, witness
rooms, jury deliberation rooms, attorney conference
rooms, prisoner holding cells, offices
of the court clerks, the United States attorney,
and the United States marshal, probation
and parole offices, and adjoining corridors of
any court of the United States.
(h) Notice of the provisions of subsections (a)
and (b) shall be posted conspicuously at each
public entrance to each Federal facility, and notice
of subsection (e) shall be posted conspicuously
at each public entrance to each Federal
court facility, and no person shall be convicted
of an offense under subsection (a) or (e) with respect
to a Federal facility if such notice is not
so posted at such facility, unless such person
had actual notice of subsection (a) or (e), as the
case may be.
(Added Pub. L. 100–690, title VI, § 6215(a), Nov. 18,
1988, 102 Stat. 4361; amended Pub. L. 101–647, title
XXII, § 2205(a), Nov. 29, 1990, 104 Stat. 4857; Pub.
L. 103–322, title VI, § 60014, Sept. 13, 1994, 108
Stat. 1973; Pub. L. 104–294, title VI, § 603(t), (u),
Oct. 11, 1996, 110 Stat. 3506; Pub. L. 107–56, title
VIII, § 811(b), Oct. 26, 2001, 115 Stat. 381; Pub. L.
110–177, title II, § 203, Jan. 7, 2008, 121 Stat. 2537.)
No person on U.S. Postal Service® property may carry or store firearms, explosives, or other dangerous or deadly weapons, either openly or concealed, except for official purposes. See Title 39, Code of Federal Regulations, Section 232.1.
(l) Weapons and explosives.
Notwithstanding the provisions of any other
law, rule or regulation, no person while on postal property may carry firearms,
other dangerous or deadly weapons, or explosives, either openly or concealed,
or store the same on postal property, except for official purposes.
The CFR carves out for "any other law" and under USC 18 930 (d)(a)3 "hunting or other lawful purposes"
well.... CC for self protection is a lawful purpose. why is this even before the supremes?
