Here is the actual CA law and CA DOJ letter pertaining to large capacity magazines.
CA Penal Code 12020
(a) Any person in this state who does any of the following is punishable by imprisonment in a county jail not exceeding one year or in the state prison:
(2) Commencing January 1, 2000, manufactures or causes to be manufactured, imports into the state, keeps for sale, or offers or exposes for sale, or who gives, or lends, any large-capacity magazine.
(b) Subdivision (a) does not apply to any of the following:
(19) The sale of, giving of, lending of, importation into this state of, or purchase of, any large-capacity magazine to or by any federal, state, county, city and county, or city agency that is charged with the enforcement of any law, for use by agency employees in the discharge of their official duties whether on or off duty, and where the use is authorized by the agency and is within the course and scope of their duties.
(20) The sale to, lending to, transfer to, purchase by, receipt of, or importation into this state of, a large capacity magazine by a sworn peace officer as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2 who is authorized to carry a firearm in the course and scope of his or her duties.
(21) The sale or purchase of any large-capacity magazine to or by a person licensed pursuant to Section 12071.
(22) The loan of a lawfully possessed large-capacity magazine between two individuals if all of the following conditions are met:
(A) The person being loaned the large-capacity magazine is not prohibited by Section 12021, 12021.1, or 12101 of this code or Section 8100 or 8103 of the Welfare and Institutions Code from possessing firearms or ammunition.
(B) The loan of the large-capacity magazine occurs at a place or location where the possession of the large-capacity magazine is not otherwise prohibited and the person who lends the large-capacity magazine remains in the accessible vicinity of the person to whom the large-capacity magazine is loaned.
(23) The importation of a large-capacity magazine by a person who lawfully possessed the large-capacity magazine in the state prior to January 1, 2000, lawfully took it out of the state, and is returning to the state with the large-capacity magazine previously lawfully possessed in the state.
(24) The lending or giving of any large-capacity magazine to a person licensed pursuant to Section 12071, or to a gunsmith, for the purposes of maintenance, repair, or modification of that large-capacity magazine.
(25) The return to its owner of any large-capacity magazine by a person specified in paragraph (24).
(26) The importation into this state of, or sale of, any large-capacity magazine by a person who has been issued a permit to engage in those activities pursuant to Section 12079, when those activities are in accordance with the terms and conditions of that permit.
(27) The sale of, giving of, lending of, importation into this state of, or purchase of, any large-capacity magazine, to or by entities that operate armored vehicle businesses pursuant to the laws of this state.
(28) The lending of large-capacity magazines by the entities specified in paragraph (27) to their authorized employees, while in the course and scope of their employment for purposes that pertain to the entity's armored vehicle business.
(29) The return of those large-capacity magazines to those entities specified in paragraph (27) by those employees specified in paragraph (28).
(30)(A) The manufacture of a large-capacity magazine for any federal, state, county, city and county, or city agency that is charged with the enforcement of any law, for use by agency employees in the discharge of their official duties whether on or off duty, and where the use is authorized by the agency and is within the course and scope of their duties.
(B) The manufacture of a large-capacity magazine for use by a sworn peace officer as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2 who is authorized to carry a firearm in the course and scope of his or her duties.
(C) The manufacture of a large-capacity magazine for export or for sale to government agencies or the military pursuant to applicable federal regulations.
(31) The loan of a large-capacity magazine for use solely as a prop for a motion picture, television, or video production.
(32) The purchase of a large-capacity magazine by the holder of a special weapons permit issued pursuant to Section 12095, 12230, 12250, 12286, or 12305, for any of the following purposes:
(A) For use solely as a prop for a motion picture, television, or video production.
(B) For export pursuant to federal regulations.
(C) For resale to law enforcement agencies, government agencies, or the military, pursuant to applicable federal regulations.
(c)(25) As used in this section, "large-capacity magazine" means any ammunition feeding device with the capacity to accept more than 10 rounds, but shall not be construed to include any of the following:
(A) A feeding device that has been permanently altered so that it cannot accommodate more than 10 rounds.
(B) A .22 caliber tube ammunition feeding device.
(C) A tubular magazine that is contained in a lever-action firearm.
CA DOJ letter Clarifying CA law regarding large capacity magazines.