California could ban it for any number of reasons or perhaps it hasn't been submitted to California for approval.
I included here the California definitions of "assault weapon" which makes it illegal for sale in this state.
#8 is a shotgun with rotating cylinder......
The term “assault weapon” also means any firearm that falls under one of the following definitions
pursuant to Penal Code section 12276.1:
(1) A semiautomatic, centerfire rifle that has the capacity to accept a detachable
magazine and any one of the following:
(A) A pistol grip that protrudes conspicuously beneath the action of the weapon.
(B) A thumbhole stock.
(C) A folding or telescoping stock.
(D) A grenade launcher or flare launcher.
(E) A flash suppressor.
(F) A forward pistol grip.
(2) A semiautomatic, centerfire rifle that has a fixed magazine with the capacity to
accept more than 10 rounds.
(3) A semiautomatic, centerfire rifle that has an overall length of less than 30 inches.
(4) A semiautomatic pistol that has the capacity to accept a detachable magazine and
any one of the following:
(A) A threaded barrel, capable of accepting a flash suppressor, forward handgrip,
or silencer.
(B) A second handgrip.
(C) A shroud that is attached to, or partially or completely encircles, the barrel that
allows the bearer to fire the weapon without burning his or her hand, except a slide
that encloses the barrel.
(D) The capacity to accept a detachable magazine at some location outside of the
pistol grip.
(5) A semiautomatic pistol with a fixed magazine that has the capacity to accept more
than 10 rounds.
(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.
California Firearms Laws 2007 11
(

Any shotgun with a revolving cylinder.
The following definitions shall apply relative to defining assault weapons:
(1) "Magazine" shall mean any ammunition feeding device.
(2) "Capacity to accept more than 10 rounds" shall mean capable of
accommodating more than 10 rounds, but shall not be construed to include a feeding
device that has been permanently altered so that it cannot accommodate more than 10
rounds.