Photo by Michael Beddow, UC Davis: closeup of microstamp on shell casing

New technology currently being tested by the University of California at Davis could make it easier for police to identify the gun from which shells left at a crime scene have been fired. The technology, called microstamping, works by stamping each shell with an identifying mark unique to the gun from which it was fired. The recently concluded study found that microstamping is feasible, however it did not work equally well for all guns and ammunition in the pilot and wider testing should be done.

Microstamping technology uses a laser to cut a pattern or code into the head of a firing pin or another internal surface. The method is similar to that used to engrave codes on computer chips. When the trigger is pulled, the firing pin hits the cartridge case or primer and stamps the code onto it. In principle, the spent cartridge can then be matched to a specific gun.

In October 2007, Gov. Arnold Schwarzenegger signed into law AB 1471, requiring that all new models of semiautomatic pistols sold in California on or after Jan. 1, 2010, be engraved in two or more places with an identifying code that is transferred to the cartridge case on firing. Similar legislation has been proposed in other states and at the federal level.

In March 2008, a report from the National Research Council, part of the National Academies of Science, described microstamping as a "promising" approach and called for more in-depth studies on the durability of microstamped marks under different firing conditions.

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