All,
There's a lot bad information above concerning shotgun magazines. The key is that certain shotguns are "Assault Weapons" and a felony to import, or possess, without a permit or registration. The key requirements are contained in California's Penal Code section 30515 quoted in pertinent part below:
(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 does not have a fixed magazine.
(8) Any shotgun with a revolving cylinder.
Many years ago, California defined a "Fixed magazine" as one that required a tool to remove. That definition is now toast. The current definition is that the action of the weapon must be disassembled in order to remove the magazine.
Additionally, please note that Penal Code section 30510 defines a number of weapons as being "Assault Weapons" regardless of their features.
California also maintains a list of "Not Unsafe" handguns that can be sold to non-exempt persons ("The Roster"). The roster has no applicability to weapons bought into the state by visitors, but the "Assault Weapon" restrictions do apply.
California generally prohibits concealed carry (both on the person and in vehicles) and loaded carry. California has two very different definitions of when a weapon is loaded. Nearly all of the state is governed by the general definition, which requires that there be ammunition in the weapon, such that it could be fired by the normal operation of the weapon. Under the general definition there is no need to keep ammunition in a separate container. But certain places in the state, including a portion of the city of Sacramento, are governed by the special definition, which holds that a weapon is loaded when the weapon and ammunition are under the control of the same person.
