may take from fifteen minutes to one hour to compare each groove, and looking searchingly into the comparison microscope is impossible for more than about three hours a day, otherwise the operator is likely to suffer severely from eye-strain, fatigue, and headache. At this rate, it would take one operator something like four or five years to search one manufacturer’s record bullets for one year’s production of one caliber of gun.

More than 70 years later, ballistic imaging technology has demonstrated its capacity to address some of these concerns, providing an initial analysis and sorting of massive volumes of evidence that—now, as then—are impossible for a human examiner to process. The question is whether the technology has advanced to the point that a massive, national database of exhibits and images from new and imported firearms is any more tractable than the collection Hatcher described as well intentioned but dangerous.

In this chapter, we present the argument from the preceding chapters in order to answer the primary, titular question of our study: Is a national reference ballistic image database (RBID) a feasible, accurate, and technically capable proposition? In Section 9–A, we discuss the basic question of how many guns would be included in a national RBID, followed in Section 9–B with an outline of other general assumptions on the shape and content of a national RBID. Subject to those assumptions, we consider in Section 9–C the technical aspects of establishing such a database from the information management and manufacturing perspectives, the statistical feasibility of such a database, and other perspectives on the issue. Section 9–D presents our general conclusions. We then discuss the implications of our conclusions on subnational, state-level RBIDs that currently exist or that may be created (Section 9–E). This is important because conclusions for or against a national RBID impact not only state RBIDs but—depending on the weight placed on supporting arguments—on the long-term viability of a crime-evidence database like the National Integrated Ballistic Information Network (NIBIN) as well. Some detailed probabilistic calculations related to the statistical feasibility of an RBID are laid out more fully in the appendix to this chapter, in Section 9–F.

9–A
A NATIONAL REFERENCE DATABASE: HOW MANY GUNS?

An important consideration in evaluating the feasibility of a national RBID is the magnitude by which ballistic imaging workload would increase: How many guns would have to be entered into such a database?

Yearly firearm production figures compiled by the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) reveal that domestic firearms manufacturers produce between 3–3.5 million firearms per year (see Table 9-1). Approximately one-third of these, on the order of 1 million,



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