Unfortunately, the state of firearm's laws in the U.S. is pitifully labyrinthine-- and H.R. 218 is no relief.
The federal government is not actually entitled to grant privileges and immunities to citizens of various states through legislation, directive or order-- though it is entitled to establish what are and are not federal laws and regulations, and Congress may, from time to time, attempt to elaborate on the Constitutional rights of all Americans through certain legislation.
If you read the law carefully, it only applies to firearms that have been involved in interstate or foreign commerce and is, quite simply, an attempt by the federal government to interfere with the sovereignty of the individual states in the guise of regulating "interstate commerce".
H.R. 218 established the privilege to carry a concealed firearm between states for qualified law enforcement officers and retired officers (who have qualified on their weapon within the last 12 months). In other words, it isn't against federal law. However, that doesn't really change the laws of the state you leave or step into-- no matter what H.R. 218 may say. The law in the individual states apply-- and in some states that means that the law from county to county and from municipality to municipality may also apply.
Even the unconstitutional act itself recognizes certain limitations:
(b) This section shall not be construed to supersede or limit the laws of any State that--
(1) permit private persons or entities to prohibit or restrict the possession of concealed firearms on their property; or
(2) prohibit or restrict the possession of firearms on any State or local government property, installation, building, base, or park.
And, of course, it doesn't limit the power of the federal government to restrict the possession of firearms on federal property or otherwise-- consistent with federal law.
Maybe someday there won't be thousands of firearms laws in the U.S. and the right to keep and bear arms for self-defense will be recognized for all peaceable citizens throughout the country. Until then, know the law wherever you intend to carry your firearm.