US Code Title 18
§ 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.
Title 39 CFR 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.
(p)
Penalties and other law. (1) Alleged violations of these rules and regulations are heard, and the penalties prescribed herein are imposed, either in a Federal district court or by a Federal magistrate in accordance with applicable court rules. Questions regarding such rules should be directed to the regional counsel for the region involved.
(2) Whoever shall be found guilty of violating the rules and regulations in this section while on property under the charge and control of the Postal Service is subject to fine of not more than $50 or imprisonment of not more than 30 days, or both. Nothing contained in these rules and regulations shall be construed to abrogate any other Federal laws or regulations of any State and local laws and regulations applicable to any area in which the property is situated.
q)
Enforcement. (1) Members of the U.S. Postal Service security force shall exercise the powers provided by 18 U.S.C. 3061(c)(2) and shall be responsible for enforcing the regulations in this section in a manner that will protect Postal Service property and persons thereon ....