For safety's sake,
Simply transport the firearms in a locked container in the trunk, unloaded. Yes, that means you cannot have them available for personal protection. Having rounds in the magazine, in the locked container, is technically not "loaded" but cops don't always know the law. Hell, most of them think that there's a "four-fingers" rule for knives... which there isn't. Being in jail sucks, so you're stuck with adhering to the dumbest possible interpretation of the law, because that's what will end being the opinion of whatever cop you are unfortunate enoguh to encounter. Murphy's Law trumps all human law.
Assault weapons law is pretty clear, except where it isn't. No semi-auto magazines over 10 rounds, except tube-fed rimfires. No AKs. No ARs, except for certain lowers that nobody outside the CA AR community knows about, including cops. No pistol gripped stocks on detachable-magazine semi-auto rifles. No detachable-mag SKSs, regardless of capacity. You do not have to remove the bayonet from your SKS, although most people (and most cops) think that you do.
Such is life, until we can get our laws changed.
As to where to shoot, target shooting is permitted on any land owned by the BLM. You must be 150 feet (maybe yards, I forget) from any road or structure, unless they are on private property and you have the landowner's permission.
Be somewhat careful, as many areas have some weird, and unmarked, boundaries, so that you can be on BLM land (legal to shoot) and then walk a few feet and be on Forest Service land (shooting only allowed in lawful pursuit of birds and mammals), or park land (no shooting at all), or private property (trespassing rules apply). Not to mention the ranchers and landowners who put up fences on public land adjacent to their property or grazing permit land, and post "no hunting or shooting" signs on it.
Leaving your targets behind, or shooting at glass is (a) really jerkish and (b) littering. I was told yesterday by a BLM ranger that, if you're at a "free range", and you shoot at an existing target left by some slob, it becomes "yours", and you're now responsible for packing it out. Whether that's true, and how it could be enforced, I don't know, but that's what the man said.
Contact the BLM and Forest Service ranger district offices for more detailed information about where you can shoot.
Be safe.
Have fun.
Enjoy California. Outside of the cities, which don't really suck any more or any less than other big cities, it's a beautiful state. If you've got the time, take the drive down Highway 1 from Santa Cruz to San Luis Obispo. It's not really describable to anyone who's never driven it.
--Shannon
