They aren't quite like USPS in that I've not heard them claiming the sidewalk as property.
TITLE 18 - CRIMES AND CRIMINAL PROCEDURE
PART I - CRIMES
CHAPTER 44 - FIREARMS
-HEAD-
Sec. 930. Possession of firearms and dangerous weapons in Federal
facilities
-STATUTE-
(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.
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(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.
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(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 2 1/2 inches in length.
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(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.
