DO NOT carry the gun loaded.
DO NOT conceal the gun or any part of it (i.e. the mag) loaded or not.
DONOT carry it outside a locked container, loaded or not,within 1000 feet of a school.
Legally, the safest way is to carry it is in a locked container. "One that does not allow access to the firearm without first opening the lock,or, destroying the lock, the locking mechanism,or the container."
The container statute, nor the case law interpreting it, does not specify any material from which the container must be made. It says "secure container". As you can see...
Calif. Penal Code § 12026.1.Firearm in trunk of motor vehicle or in locked container(a)Section 12025 shall not be construed to prohibit any citizen of the United States over the age of 18 years who resides or is temporarily within this state, and who is not prohibited by state or federal law from possessing, receiving, owning, or purchasing a firearm, from transporting or carrying any pistol, revolver, or other firearm capable of being concealed upon the person, provided that the following applies to the firearm:(1)The firearm is within a motor vehicle and it is locked in the vehicle's trunk or in a locked container in the vehicle other than the utility or glove compartment.(2)The firearm is carried by the person directly to or from any motor vehicle for any lawful purpose and, while carrying the firearm, the firearm is contained within a locked container.(b)The provisions of this section do not prohibit or limit the otherwise lawful carrying or transportation of any pistol, revolver, or other firearm capable of being concealed upon the person in accordance with this chapter.(c)As used in this section, "locked container" means a secure container which is fully enclosed and locked by a padlock, key lock, combination lock, or similar locking device.