Fortunately for us, it's pretty difficult to 'register' a gun without actually having that gun. If the FFL were to write down the SN he would most likely LOOK at the firearm to verify the SN, just like the police would. Also one cannot commit a crime with a 'virtual gun', and certainly there is no reason why any SN would track back to you, the legal owner, without the SN also appearing on the 'crime gun' which would be impossible. The only criminal activity with a public SN (since identify theft of a firearm is completely different than identify theft of a human), is if some garage gun builder stamped YOUR SN on a newly manufactured garage gun (like the handbuilt AKs in Peshawar, etc.) but that's unlikely and a ton of work for little return on investment.

The primary reason I alter or obscure SNs is not because of crooks. It's because of COPS. In the early days of the Internet, I had a pristine side photo of one of my movie guns and you could see the SN clearly. Apparently there were enough BORED COPS throughout the 50 states in the union to run a check on the serial number to see who it belonged to. Well, it was a legally owned firearm and wasn't tied to any crime right? Well, the ATF contacted me and asked me why 19 different police departments were running a check on my gun?!?!?!?!?! DOH!
http://ivo.co.za/wp-content/uploads/...impson-doh.jpg

You pretty much covered all of it, nice work.

Well, now I'm not worried anymore. I figured posting a gun serial number was like posting a license plate number or something. Guess I was right. I still appreciate the concern though, I sure don't want to get arrested or something.