yeah, but most officers would be happy to run a check on a firearm for you (in my experience).....although, if it comes back that it is stolen they are required to confiscate it
Exactly why it should be run before you purchase. In my experience their are always officers at gun shows. You can probably tell the seller to follow you over to one of the cops so they can run the serial number. If the seller refuses or gives a lame excuse why you shouldn't bother with it, then it would be a good indicator not to purchase. :-)