Just to clear up some things from previous posts:
Everything Brown has done so far is legal. The Assembly Bills are all legal in their origin, their contents may be up for challenge, but nothing was done in secret or "mandated" upon people. The bill that outlawed open carry was up for a vote through the legislative process. Jerry Brown just signed it. We live in a republic let's not forget..... There was no failure of procedure. You could have fought to keep it if you had so desired.
In California we are lucky in that we have the Initiative process. Jerry Brown did not "have the citizens vote" on anything as if it were some kind of decree. He used the process, like many other governors before him, and you can use too, to get something on the ballot that the voters could vote on directly. Arnold loved this process because he felt he could take things directly to the voters when the legislature failed to act.
As the previous poster mentioned, there are several Assembly Bills, Senate Bills etc that aim to curb gun ownership in several ways. You can fight these as a California resident. You can also get your own Initiative on the ballot and null and void all of them if you would like.
Some of these bills may suck horribly, but the Supreme Court has made it clear the states CAN restrict the right to bear arms in reasonable ways. In particular HR 1 will pass without issue and is in place in MANY states already. Some of the others will not pass as they stand now, AJR 5 will pass most likely as is completely constitutional to offer support and "urge" congress to act on something.
Our best bet is to defeat these bills before they ever get going. Trying to sue after the fact is just very rough.