Kenshin,
To answer your question to the best of my knowledge, I pull 12276.1 out from CA DOJ's very own website.
12276.1. (a) Notwithstanding Section 12276, "assault weapon" shall also mean
(6) A semiautomatic shotgun that has both of the following:
(A) A folding or telescoping stock.
(B) A pistol grip that protrudes conspicuously beneath the action of the weapon, thumbhole stock, or vertical handgrip.
(7) A semiautomatic shotgun that has the ability to accept a detachable magazine.
(8) Any shotgun with a revolving cylinder.
In other words, we can legally own a shotgun with a pistol-gripped stock here in the state of California.
As to how the legalese is applied for imported semiautomatic shotguns such as the Fabarms and Benellis, I haven't found a clear answer as that falls under Federal law.
Here's a link to some massive discussion with regard to a telescoping stocks.
ar15.com
-Jim