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.
NFA weapons refer to a federal list of firearms that the government requires owners register. Not all states follow this law, and others have partial restrictions, full banns, or the need to register firearms in the NFA data base. Examples of firearms or other weaponry considered a NFA regulated weapon includes, but is not limited to: Machine guns, firearm suppressors, short barreled riffles and shot guns, and anti-tank guns (.50 caliber and up).