As a matter of course, any firearm used in a reported criminal incident (including a self defense incident) will have a NCIC check done on it. That being said, once it has been determined not to be stolen, the person possessing it is usually listed as the legal owner. If you have paperwork all the better. (I'm a active duty police officer and most of the stuff we recover is used illegally and/or stolen but if you used something you can legally own, you are in good shape)
"Badges? We ain't got no badges. We don't need no badges. I don't have to show you any stinking badges."