Keep in mind that California law treats handguns on the "Safe Handgun Roster" and "Illegally Configured" weapons separately.
The "Safe Handgun Roster" lists weapons that have been tested by a DOJ-Certified lab as meeting California's safety requirements. A California dealer cannot sell a handgun to a non-exempt person unless it is listed on the roster. A non-exempt California resident cannot import an off-roster handgun that they acquired outside of the state while a resident of California.
But the roster does not apply to handguns that are bought into the state by visitors and new residents.
However, California does have some configuration requirements that are unique to California, and that apply to all weapons and persons. The first of these is the "Assault Weapon" statute. A semi-auto handgun having a detachable magazine and a threaded barrel is an "Assault Weapon" and a felony to possess unless registered or permitted as an "Assault Weapon." A 1911 with a compensator would be an illegal "Assault Weapon."
California has chosen to define "Short Barrel Shotgun" differently than does the federal law. The result is that .45/410 Gauge weapons like the Taurus "Judge" are illegal "Short Barrel Shotguns."
California has very strict penalties for Carrying Concealed without a Permit, and for Carrying a Loaded Firearm where prohibited. A first time offense for either is a felony if the weapon is not registered in the California DOJ system to the offender. Also please note that unloaded "Open Carry" is prohibited in most populated areas of the state.
California has two different definitions of when a firearm is loaded. Under the general definition, there must be ammunition in the weapon that could be fired through the normal manipulation of the weapon. It is not required that a round be in the chamber, but there is case law holding that shotgun shells in a buttstock sleeve did not make the shotgun loaded. Under the special definition (only applicable to certain situations and locations), a firearm is loaded whenever the weapon and ammunition are under the control of the same person, even if the weapon and ammunition are in separate locked containers.
California has a statute that bans the manufacture, importation and possession of magazines with a capacity of more than 10 rounds. That statute is currently being challenged on constitutional grounds. The District Court has issued an injunction prohibiting enforcement of the possession clause of the statute. The provisions against manufacturing and importation still remain. Violation is a felony. (Credit to "LiveLife" for the reminder on this point)