CA Fish & Game Code Section 2006

(a)

It is unlawful to possess a loaded rifle or shotgun in any vehicle or conveyance or its attachments which is standing on or along or is being driven on or along any public highway or other way open to the public.

(b)

A rifle or shotgun shall be deemed to be loaded for the purposes of this section when there is an unexpended cartridge or shell in the firing chamber but not when the only cartridges or shells are in the magazine.

(c)

The provisions of this section shall not apply to peace officers or members of the Armed Forces of this state or the United States, while on duty or going to or returning from duty.