Laws governing silencers: http://ag.ca.gov/firearms/dwcl/12500.php - - - - [Here is an EXCERPT from the website for you] - - - - 2007 Dangerous Weapons Control Law 12500 thru 12520 Silencers CHAPTER 5. FIREARM DEVICES ARTICLE 1. GENERAL PROVISIONS * 12500. The term "silencer" as used in this chapter means any device or attachment of any kind designed, used, or intended for use in silencing, diminishing, or muffling the report of a firearm. The term "silencer" also includes any combination of parts, designed or redesigned, and intended for use in assembling a silencer or fabricating a silencer and any part intended only for use in such assembly or fabrication. * 12501. Section 12520 shall not apply to, or affect, any of the following: (a) The sale to, purchase by, or possession of silencers by agencies listed in Section 830.1, or the military or naval forces of this state or of the United States for use in the discharge of their official duties. (b) The possession of silencers by regular, salaried, full-time peace officers who are employed by an agency listed in Section 830.1, or by the military or naval forces of this state or of the United States when on duty and when the use of silencers is authorized by the agency and is within the course and scope of their duties. (c) The manufacture, possession, transportation, or sale or other transfer of silencers to an entity described in subdivision (a) by dealers or manufacturers registered under Chapter 53 (commencing with Section 5801) of Title 26 of the United States Code, and the regulations issued pursuant thereto. ARTICLE 2. UNLAWFUL POSSESSION OF FIREARM SILENCERS * 12520. Any person, firm, or corporation who within this state possesses a silencer is guilty of a felony and upon conviction thereof shall be punished by imprisonment in the state prison or by a fine not to exceed ten thousand dollars ($10,000) or by both.

From my answer here to Where can I buy a silencer? http://www.answerbag.com/q_view/7867 First, make sure you are able to legally purchase a silencer :) Unlike conventional firearms, each change of possession or ownership of a Title 2 weapon (silencer, machine gun, sawed-off shotgun, pengun, etc.) must be approved in advance by BATF. This includes not only the sale of such a weapon, but also the act of giving or loaning it to another person. Failure to comply can result in a $250,000 fine, 10 years in prison, or both. Although the weapon can be moved by its registered owner within the owner's state or residence, transportation across state lines requires prior BATF approval. These requirements were instituted by the National Firearms Act of 1934 and were incorporated into the Gun Control Act of 1968. To the best of our knowledge, silencers are legal for private ownership in the following states: AL, AR, AK, AZ, CO, CT, FL, GA, ID, IN, KY, LA, ME, MD, MS, MT, NE, NV, NH, NM, NC, ND, OH, OK, OR, PA, SC, SD, TN, TX, UT, VA, WA, WV, WI, and WY. Additionally, they maybe owned by Class 3 dealers and Class 2 manufacturers (but not individuals) in: CA, IA, KS, MA, MO, and MI. Territorial law prohibits possession in the Territories and Possessions of the United States. There are no known restrictions on governmental ownership. If your state is not listed, check with your local office of the Bureau of Alcohol, Tobacco, & Firearms or your state's Attorney General. If they are not legal in your state of residence, we cannot sell to you. Please do not ask us to violate state or federal law. As with any firearm, an individual owner must take possession through a licensed dealer in his state of residence. In the case of Title 2 weapons (silencers, machine guns, etc.), the dealer must be what is known as a class 3 dealer, meaning that he has paid an annual special occupational tax in conjunction with his firearms license to permit him to deal in Title 2 weapons without paying the individual $200 transfer tax on each weapon. The $200 transfer tax is assessed each time a Title 2 weapon changes hands. The exceptions are to (or from) a governmental agency or a class 3 dealer. Interestingly, many class 3 dealers do not have a storefront and deal in these weapons as a sideline.. Each time a Title 2 weapon changes hands, the transfer must be approved in advance by the Bureau of Alcohol, Tobacco & Firearms. It normally takes 4-5 weeks for BATF to approve the transfer between dealers or to law enforcement agencies, and the transfer to individuals requires 3-4 months. The procedure for obtaining one of our suppressors is to order (and pay for) the unit. The weapon should be ordered through your class 3 dealer. Although you may order direct, it must be delivered through your dealer. We then transfer the weapon to your class 3 dealer. Your dealer will then assist you in completing the necessary paperwork to transfer the weapon to you. This will include your submitting fingerprints and two passport size photos on your application. In addition, your local chief law enforcement officer (sheriff or chief of police) will need to sign the application. Along with your $200 transfer tax, the application is sent to BATF. When the application is approved (and not before), your dealer turns over possession to you. Your dealer will charge a fee for handling of the weapon. We are not in the business of being a sales tax collector for states other than Idaho, but we do not encourage your avoidance of sales or use taxes. If you are eligible to own any conventional firearm, you are also eligible to own a Title 2 weapon provided that there are no state laws prohibiting such ownership. This means basically that you must be free of all felony convictions and be over 21 years of age. Your dealer can usually help you find a suitable law enforcement signature in the rare instance where your sheriff is personally anti-gun and refuses to sign your application. Your other option is to form a corporation, which does not require a law enforcement signature. Federal law prohibits exportation of silencers except to governmental agencies with an End User Certificate. Please contact us by telephone for further details if you represent a foreign government agency. You might google for an answer at http://www.google.com/ or try this site http://www.impactguns.com/store/silencers.html