From the New York Times article today, Law Bars a National System for Tracing Bullets and Shells:

"The technology exists to create a national ballistic fingerprint system that would enable law enforcement officials to trace bullets recovered from shootings, like those fired by the Washington-area sniper, to a suspect."

"Such a system would have been of great use in the Washington case, in which six people were shot to death, because so far bullet fragments are virtually the only evidence."

"But because of opposition by the gun industry and the National Rifle Association, only two states have moved to set up a ballistic fingerprint system, and Congress has prohibited a national program, experts say."

A relatively new system " known as the National Integrated Ballistics Information Network, optically scans the markings on bullets or shell casings, converting them into an electronic signature. This information is stored in a database and can be retrieved by computers in 235 police departments around the nation."

Many in law enforcement as well as gun control advocates want to require "gun manufacturers to keep an electronic record of the markings from bullets and shell casings when new guns are test fired. This data would be kept with the serial numbers of the guns. With this information, the agency would be able to trace bullets and shell casings found at a shooting site to the gun maker and eventually to the buyer."

The National Rifle Association opposes such a measure saying it would be the equivalent of a national gun registry. The NRA was successful in having a provision included in the 1968 federal Gun Control Act banning a national gun registry.