"The law, which does not apply to long guns, will take effect July 1. The new measure also increases certain penalties. For example, theft of a firearm — now a misdemeanor that carries a 30-day sentence — will become a felony with a mandatory six month incarceration. It also makes exceptions for people with certain mental illnesses and criminal convictions."
No matter what laws are in effect in any state, federal laws may be given priority, i.e., while on federal property or in a federal building. Leave the state, and you must abide by that state's laws as well as applicable federal laws. Use your weapon in the commission of a federal crime and only federal laws apply, and you have no argument when your weapon is confiscated.