http://www.nssf.org/share/legal/docs/AFTEVol38No1KrivostaNanoTag.pdfNanoTag™ Markings From Another Perspective
By: George G. Krivosta, Suffolk County Crime Laboratory, Hauppauge, New York
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The next series of tests involved placing the NanoTag™ firing pin “0H5K B4M3” into ten different Government Model pistols of different manufacturers and vintages. Firing pins are generally designed to be easily removable for cleaning or replacement. It takes about ten seconds to remove the firing pin from a Government Model pistol and about fifteen seconds to place it back into the weapon. The NanoTag™ firing pin was placed in each weapon and was test fired with ten Winchester brand .45 auto caliber cartridges. Each of these expended cartridge cases was microscopically examined to determine the legibility of the pin’s serial number. If all eight of the characters were decipherable, that impression was graded “Satisfactory” (figure 7). If one or more of the characters was un-decipherable that impression was graded “Unsatisfactory” (Figures 6, 6a). The overall ratio of Satisfactory to Unsatisfactory impressions was 54 to 46.
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The common layman seems to believe that two bullets fired from the same weapon are identical, down to the very last striation placed on them by the weapon. The trained firearms examiner knows how far that is from reality. The layman might also take as gospel that if you could find a way to place a number onto the tip of a firing pin, then you could certainly read it in the impression. Not until this research was performed and many test fires examined from a firing pin that had a known recognizable pattern, did it become apparent how much change could take place, and why matching firing pin impressions can be so challenging.
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Certainly this research has shown that implementing this technology will be much more complicated than burning a serial number on a few parts and dropping them into firearms being manufactured.
Much more available at the link. Even without intentional defacement, only half of the brand new firing pin impressions could be read reliably by a crime lab examiner.
Microstamping is an unreliable technology easily circumvented intentionally or by natural wear. The funny thing about California's AB1471 (the law mandating microstamping)? The police are exempt. If the technology were actually reliable, wouldn't the legislators want the police to follow the same requirements?
eta: Woops, forgot the link.
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