To sort of expand on what Tailo said, the NFA stamp is a tax stamp. It's tax information, but regulated by the BATFE. Many local LEOs are not very familiar with the NFA process. You have no requirement to produce the tax stamp without a subpoena. How you wish to proceed is based on your own personal philosophy. As Tailo pointed out, refusing to cooperate may be your right, but there are side-effects relating to you being inconvenienced. If a LEO does have the initiative, they can detain you in accordance with their state laws to obtain a subpoena to force you to produce the documentation. Or, if they can articulate suspicion that the gun may not be legal, they can impound it until there is proof. This can happen from a number of ways. If I see a guy with an SBR in his car that is obviously a custom build, and I inspect the rifle and do not see the manufacturer of the SBR engraved on the receiver, that is a clue that the rifle may not be legal. However, if I see it engraved, then it would be more justifiable for me to identify the guy, photograph the weapon, take measurements, and then send the guy on his way. I could then submit the information for a subpoena and obtain the information either from him, or directly from the BATFE through our regional branch office. On the other hand, what I do is carry a small 3x5 laminated copy of my Form 1/Form 4 with stamp, with the stamp serial number visible, on my weapon. Every SBR I own has a laminated mini copy of my NFA paperwork in the grip of the weapon. I can quickly pull out the paperwork and show someone it's legit. If they had further questions, they would have difficulty further detaining me or impounding my weapon at that time because the presence of a copy of the paperwork would likely be enough to eliminate PC or RAS for a detention. Now, inside of your state is on you. However, if I'm in Wisconsin or Nebraska at a shooting course, I'd much rather be done and over with the interaction in 20 minutes than to have my rifle taken for two weeks and then have to drive 6 hours back down to another state to go pick it up.
Again, it's all dependent upon LEO knowledge, which is unfortunate in some respects. I know that people like JonJon will tell you to hold fast and not give up any information, and you would not be wrong in this. This is a legitimate reaction, provided you have confirmation of the ability to do so from your legal counsel/lawyer. Understand that this method does make it a bit more necessary to have the phone number of a good NFA-educated attorney at your disposal in case you have concerns or issues arise.
Obviously, IANAL; and being in LE, I will have a different perspective. It's up to you to decide which option you would choose.
With all that being said, I've never had an issue with any LE. My problem has always been with moron know-it-alls at public ranges who think they are God's gift to firearms knowledge, and try to accuse you of breaking the law because they're too ignorant of gun laws. I have had to "educate" several people at ranges about the legality of NFA subjects like SBRs, and had to explain to them that it's none of their damn business how I conduct my own personal firearms affairs. Sometimes I think gun owners can be our own worst enemies.
Keep in mind that I'm not suggesting what any of you should do one way or the other. I'm just explaining some options.
Last edited by Reedo302; 04-23-2012 at 02:50 PM.