Every state has different laws regarding guns and whether they can be carried. In some states you can conceal them, in other states you cannot. In some states you need a permit to carry, in other states you do not. California has a unique law -- you can carry a gun, but it must not be concealed, and it must not be loaded.
California's Open Carry law states very clearly that it is not illegal to openly carry a gun that is unloaded. However, according toCaliforniaOpenCarry.org, it is illegal in the following places:
-- schools and "school zones" (within 1000 feet of a K-12 school)
-- California State Parks
-- "federal facilities" within the National Parks
-- US Post Offices and other federal buildings
-- any state or local public building or at any legislative meeting required to be open to the public
-- the State Capitol, legislative offices, office of the Governor, Governor’s residence, etc.
-- “sterile areas” (areas where access is controlled by security screening) of airports
-- areas restricted by local city or county ordinance, often including regional parks
The site points out that there is a myth that if a person is carrying ammunition but it is not in their gun it could be considered "loaded" and thus illegal. That is not true, unless the person is doing so with the intent to commit a felony.
Many police officers either don't know or understand the law, so it is not unusual for an officer to stop and possibly arrest a person for legally carrying an unloaded gun openly. Departments are trying to educate officers and the public about the law. In a 2008 memo, the Los Angeles District Attorney's office wrote:
Police may stop a person who is openly carrying a firearm in a belt holster and may inspect to see if the firearm is loaded. Prompt incidental checks on the person and the weapon may provide probable cause for arrest; however, the person may not be arrested for violating PC § 12031 if ammunition is not in or attached to the weapon so as to allow it to be fired, even though the person may have access to matching ammunition.