The 1989 California AWB started out by banning firearms by name and model number. Anyone owning one of the listed firearms had to have it registered by 3/31/92. The second version of the ban listed features, ie; semi auto, flash suppressor, abilty to take detachable magazines, pistol grips, etc..... these firearms had to be registered by 12/31/00.
So basically if you had them before a certain date and then registered them, you can keep them or sell them out of state or move them out of state. You cannot buy new listed firearms or bring into the state any firearms that fall under the list.
There are a few exceptions to this. One is if you are moving into the state you can bring one in, but only AFTER a background check has been done on you and you pass (You have to turn the gun over to an FFL while this is being done). The other exemption is for LEO's and they must have a departmental letterhead approving the purchase for duty use.
Included in the AWB are centerfire rifle & pistol magazines with a capacity of more than ten rounds. If you possessed them prior to the ban you could keep them, but no more are allowed into the state (Again the exeption here is fro LEO's). As some have stated before, magazines are not serial numbered, so how would anyone know, and that is true. The only ones you could not possess are the LEO marked ones or ones with a manufactured date on them.
Take a look at these links for further info:
caag.state.ca.us/firearms/forms/pdf/awguide.pdfcaag.state.ca.us/firearms/dwcl/12275.htmMy guns are pictured here:
www.ar15.com/forums/topic.html?b=3&f=118&t=187750&page=37