I’d submit that there are state legislatures, my own state of Connecticut for one, that would craft its tort law such that the simple act of owning a gun, that was subsequently used in a crime, is grounds for a law suit in civil court. You then get to spend your hard earned money defending how you stored the weapon, and proving that you were prudent in its storage, and were not negligent in any way. Then you get to sit around and hope that a jury finds the preponderance of the evidence is in your favor. The more infamous the crime committed with the stolen weapon, the more likely you will be found liable. It is just human nature, and our civil system often brings that quickly to light.
The law suits will go something like this, You owned the weapon, it was stolen, if you had not had the weapon to be stolen, then thus and such criminal would not have had it to commit this or that heinous crime. As the legal owner of the weapon you are liable for the pain and suffering of the victims, because you were negligent in its storage. A database of ‘weapon signatures’ only makes this simpler. No longer to they need the weapon, just a spent round or casing, to ‘prove’ your weapon was used. Now, I’m talking civil court here, where the rules are a lot more liberal. It even likely that you will be sued for this negligence without anyone having been ever criminally charged for the crime. Your weapon injured my client, you have to pay for damages.
In effect, the law would place the burden on you, the owner, to demonstrate that the weapon was adequately stored. I can see the juries interpretation of adequate varying widely from case to case. Even if you win the lawsuit, if the suit brought against you had prima fascia merit, and the tort law could make that easy to prove, your recourse to recover your expenses from this trial will be limited at best, impossible at worst. Just one more area for the anti-gunners to score points, by making gun owners fear the financial repercussions of gun ownership.