Indeed, the organizer of the Stop Concealed Carry Coalition is mis-informed, if he thinks Federal property is gun-free. I guarantee you there are guns in that building.
According to Federal Law,
18 U.S.C. 930
(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.
...
(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;
...
(e)
(1) Except as provided in paragraph (2), whoever knowingly possesses or causes to be present a firearm 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).
So the Cliff's Notes version of this is that if you are one of the 'special' people (a judge, a law enforcement officer, etc), you can have a gun. And we all know that those people never commit crimes with guns, right?
Oh, wait...
Dec 4, 2012 - Civil Suit Seeks To Hold City Responsible For Murder Committed By Phila. Police Officer
PHILADELPHIA (CBS) – Trial resumes this morning in a federal civil case which seeks to hold the city of Philadelphia liable for a murder committed by a police officer in Port Richmond in 2009. The suit seeks millions in damages.
But, the city contends the officer was off-duty when he intervened in a dispute outside his home and shot 21-year-old Billy Panas. Former officer Frank Tepper is now serving a life sentence for the murder.
http://philadelphia.cbslocal.com/2012/12/04/civil-suit-seeks-to-hold-city-responsible-for-murder-committed-by-phila-police-officer/

What is the point of rules that are not enforced?