Building a Comprehensive Ballistics Database?

Linuxathome asks: "I'm a resident in the Washington DC-Baltimore Metropolitan area. If you've kept up with the news lately, you've probably have heard about the serial killings. I realize that this question may spark a political debate, but my question pertains to current technology. The gun law debate has been recently re-ignited. And the hot topic of current is in regards to fingerprinting firearms. Gun rights supporters argue that the technology behind fingerprinting is not reliable (see John Dingell). Dingell estimates there are approximately 50 million gun owners in the US (I don't have estimates of how many guns are out there). Is an image database of 50 million spent casings not feasible?" What issues, both technical and political, would there be surrounding the creation (and the current hold up) of such a database?