People often have their lawfully owned and registered firearms seized by law enforcement in the course of an arrest. For instance, a person arrested for a violation of Penal Code section 25850 (c)(7) - carrying a loaded firearm in a vehicle - will most likely have that firearm seized by law enforcement as a result of the arrest, even if the firearm is lawfully owned and registered to them.
People that have their lawfully owned and registered firearms seized as a result of an arrest can potentially have those firearms returned to them. The law does not permit the retention of firearms lawfully possessed by a person at the time of the arrest upon charges which he is subsequently exonerated. See Espinosa v. Superior Court (1975) 50 Cal.App.3d 347, 353.
This means that if a person is arrested for carrying a loaded gun in a vehicle, and the charges are ultimately dismissed or the person is acquitted at a jury trial, then the person has a right to have that firearm returned to them. In order to have the firearm returned to them, the person's lawyer should file a non-statutory motion to return property, and provide an order to the judge ordering law enforcement to release the firearm(s) back to the person. The person will then be required to fill out the Law Enforcement Release of firearms form by first creating an account with the California Firearms Application Reporting System.
The CA DOJ no longer accepts paper applications to return firearms in the possession of law enforcement.