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Statistical Validation of the Individuality of Guns Using High Resolution Topographical Images of Bullets

NCJ Number
Date Published
October 2010
49 pages
Given that a previous study validated the premise that the features transferred from a gun barrel to a bullet are sufficiently unique to allow for a one-to-one association between the barrel and the bullet, except for very poor or very good quality barrels, the current study sought to extend the favorable results obtained in the previous study to barrels of very poor and very good manufacturing quality for both pristine and damaged bullets.
The current study concluded that the trueness of the premise that barrel markings on the bullets fired from a gun are unique to that gun can be extended to the majority of such barrels. Among the barrel brands used in this study, the notable exception to the premise was barrels of Bryco manufacture. For these barrels, the variability found on bullets fired by the same barrel was so extreme that the feasibility of a reliable identification of the firearm from a bullet it fired was questionable; however, another important conclusion is that the ability to determine that a given bullet has been fired by a specific barrel depends on the individual barrel itself and not only on the brand of its manufacture. In addition, the performance of the automated analysis system used in this study is not representative of that of a trained firearms examiner. A trained firearms examiner will perform better than any automated system, because humans have the ability to perform "pattern matching," and this ability is difficult to replicate by an automated system. From the current study, it is clear that the next step in automated ballistic identification techniques will require a different approach to the characterization of the land engraved areas (LEAs), which is the signature generation process. Similarly, innovations will be required in the correlation of these signatures. 23 figures, 5 references, and appended data for the testing of each manufacturer's barrels

Date Published: October 1, 2010