California has a ban on silencers/suppressors. DD must be designated as Curios & Relics, and the person must have a collector's permit, otherwise they are banned. A "Dangerous Weapons Permit" is required for the possession of shot barreled riffles/shotguns and automatic weapons. These permits are usually granted to the film industry and are extremely hard to obtain otherwise. Most AOW's are banned. The only exceptions are smoothbore firearms and pistols that have a combination smoothbore a riffle barrel.