I live in california and I have a 1300 defender with a folding stock, tactical light and two side saddles... if nobody responds to this Im going to assume its all legit.
There are no specific California regulations for pump shotguns. They are regulated by the National Firearms Act of 1934 which says the barrel must be 18" or over, and the overall length must be 26" or over.
But a pump action isnt considered "semi-auto" is it? I've shot my bad boy plenty of times at the local range (often shooting next to some kind of a law enforcement official) and nobody has had a single bad word for me.