BostonTeaParty:
Here is a link to some general information about transporting firearms in California:
http://caag.state.ca.us/firearms/travel.htm
As far as assault weapons go, the way I read state law is that nonresidents such as yourself can bring assault weapons into the state only if you are going directly to or from an organized, sponsored competition where you are going to use the assault weapon; the competition is conducted at a licensed target range; and you transport the assault weapon unloaded in a locked container.
Here are the specific sections from the Cal. Penal Code:
12280. (a) (1) Any person who, within this state, manufactures or causes to be manufactured, distributes, transports, or imports into the state, keeps for sale, or offers or exposes for sale, or who gives or lends any assault weapon, except as provided by this chapter, is guilty of a felony, and upon conviction shall be punished by imprisonment in the state prison for four, six, or eight years.
...
(b) Except as provided in Section 12288, and in subdivisions (c)and (d), any person who, within this state, possesses any assault
weapon, except as provided in this chapter, is guilty of a public offense and upon conviction shall be punished by imprisonment in the
state prison, or in a county jail, not exceeding one year....
...
(p) Subdivisions (a) and (b) shall not apply to the possession and importation of an assault weapon into this state by a nonresident if
all of the following conditions are met:
(1) The person is attending or going directly to or coming directly from an organized competitive match or league competition that involves the use of an assault weapon.
(2) The competition or match is conducted on the premises of one of the following:
(i) A target range that holds a regulatory or business license for the purpose of practicing shooting at that target range.
(ii) A target range of a public or private club or organization that is organized for the purpose of practicing shooting at targets.
(3) The match or competition is sponsored by, conducted under the auspices of, or approved by, a law enforcement agency or a nationally or state recognized entity that fosters proficiency in, or promotes
education about, firearms.
(4) The assault weapon is transported in accordance with Section 12026.1 or 12026.2.
(5) The person is 18 years of age or over and is not in a class of persons prohibited from possessing firearms by virtue of Section
12021 or 12021.1 of this code or Section 8100 or 8103 of the Welfare and Institutions Code.
....
As far as I can tell, these are the only conditions under which a nonresident can bring an AR-15 into California under state law. Whether the federal law you cited trumps state law, I have no idea, but if it were me, I wouldn't want to be the test case. I would bring a shotgun or a lever action rifle instead!
Hope this helps,
Ed, Esq. [:D]