So - What are they going to do now - Go door to door confiscating weapons? What a feel good joke.
Don't know but CA, in general, has been anti-gun for a long time so I wouldn't doubt some record is present that would enable a mass confiscation.
All they have to do is give a deadline for turning them in and a lot of people will willingly give them up. Make just a couple of highly publicized raids and the sheeple will rush to disarm themselves, never realizing that they have just been victimized by the government.