Seven years ago, New York started a database of "ballistic fingerprints" for all new handguns sold in the state. The bill's backers sold it as a crime-solving device, arguing that the state would now have a sample of a spent shell and bullet for every new gun sold. This, they said, would help police connect future evidence from crime scenes to specific guns.
Since then, the authorities have entered 200,000 newly purchased guns into the database and spent $1 million dollars a year on the system. Yet it hasn't led to a single solved crime. The only other state with such a database, Maryland, can attribute at least one conviction to the system since it was created in 2000-more than zero, but few enough that the state's own Police Forensics Division has suggested scrapping the program because of its demonstrated lack of benefits.
This hasn't come as a surprise to gun rights activists, who pointed to several potential problems when the databases were originally debated. Among them: The markings left by a gun are not guaranteed to be the same over the long term and can be deliberately changed with simple expedients such as filing inside the barrel; the vast majority of guns used in crimes are stolen or otherwise obtained in a black market, not used by their original legal owner; devoting so much record keeping to every gun sold guarantees wasted effort, since less than 1 percent of all guns sold will ever be used in a crime.
Article here. Apart from the almost complete failure of the existing databases in helping solve crimes, the other, more pernicious attribute of such databases is that they create a de facto gun registration scheme. And as history has shown us time and again, gun registration is often the first step towards gun confiscation. Indeed, registration is a necessary first step. And governments have murdered hundreds of millions of their own disarmed citizens within just the last century. Such atrocities are far more likely against an unarmed populace than an armed one.