Ok I'm working on getting my silencer here in Washington State and I know I cant shoot it here but I have a good friend in Idaho who has a small range behind his house, what do I need to take with me as far as paper work?  Also what do I need to do to take it to Idaho is there any legal work I need to do first?  Also I did a search and cant find it now but I know I saw the article here that states I can do everything except shoot it here.  The reason is I have a aquaitance how is a small town cop who informed me it is illegal to mount it up here, where I informed him he is wrong but you know town clowns they know it all, I just want to show him that I can.
Thanks,
Mike

Long story short, Employ/Use = Putting a bullet down the tube.

ATTORNEY GENERAL OF WASHINGTON CRIMES -- FIREARMS     It is not unlawful under RCW 9.41.250 to merely possess a device for suppressing the noise of a firearm.                         August 30, 1988 Honorable Kent Pullen                             Cite as: State Senator, 47th District                      AGO 1988 No. 16 Institutions Building Olympia, Washington 98504 Dear Senator Pullen:     By letter previously acknowledged, you have asked for our opinion on a question we have paraphrased as follows:     Is it unlawful under RCW 9.41.250 to possess a device for     suppressing the noise of a firearm?     We answer your question in the negative for the reasons set forth in our analysis.                            ANALYSIS     RCW 9.41.250, the provision about which you have inquired, provides:     Every person who shall manufacture, sell or dispose of or have     in his possession any instrument or weapon of the kind usually     known as slung shot, sand club, or metal knuckles, or spring     blade knife, or any knife the blade of which is automatically     released by a spring mechanism or other mechanical device, or     any knife having a blade which opens, or falls, or is ejected     into position by the force of gravity, or by an outward,     downward, or centrifugal thrust or movement; who shall     furtively carry with intent to conceal any dagger, dirk,     pistol or other dangerous weapon; or who shall use any     contrivance or device for suppressing the noise of any     firearm, shall be guilty of a gross misdemeanor. (Emphasis added.) Hon. Kent Pullen                2                 AGO 1988 No. 16     In essence, your question is concerned with whether the term "use" in the underscored language of RCW 9.41.250 includes mere possession of a noise suppression device.  Absent a statutory definition, words in a statute are to be given their ordinary meaning.  Davis v. Department of Empl. Sec., 108 Wn.2d 272, 737 P.2d 1262 (1987).  The ordinary meaning of the term "use" is to put a thing into service or action.  Webster's Third New International Dictionary, 2523-2524 (1981).  Thus, the use of a device for suppressing the noise of a firearm contemplates employing that device or putting it into service.  Although use of such a device may be incident to possession, use is quite different from simply possessing the device or exercising control over it.     In our opinion, the language of RCW 9.41.250 about which you have inquired is unambiguous.  It does not prohibit mere possession of a device to suppress the noise of a firearm.     Even if the term "use" in RCW 9.41.250 were ambiguous, rules of statutory construction would dictate against interpreting the term to include mere possession.  First, RCW 9.41.250 is a criminal statute.  Where two reasonable constructions of a criminal statute are possible, a court is required to adopt the interpretation most favorable to a person accused of violating the statute.  State v. Gore, 101 Wn.2d 481, 681 P.2d 227 (1984).  Here, of course, that would be an interpretation excluding mere possession.  Second, where the Legislature employs certain language in one part of a statute and different language in another part, a difference in legislative intent is indicated.  United Parcel Serv., Inc. v. Department of Rev., 102 Wn.2d 355, 687 P.2d 186 (1984).  The Legislature has employed the term "possession" in RCW 9.41.250 and thereby has made mere possession of certain weapons a misdemeanor. The Legislature did not employ that same term with reference to noise suppression devices.  According to this rule of construction, the Legislature's failure to do so indicates that it did not intend "use" to include mere possession.     We trust that the foregoing will be of assistance to you,                           Sincerely,                      KENNETH O. EIKENBERRY                        Attorney General                            [signed]                          Maureen Hart jf               Sr. Assistant Attorney General

Regardless of the law, an LEO might take possession of a firearm with an attached silencer and let the court decide whether or not is is illegal.

From what I gather you want to keep a copy of your approved transfer form with you any time you are in possession of an NFA item. Keep the original in a fire proof (ATF proof) safe deposit box.

Yes but are bank safe deposit boxes ATF proof