NCJ Number
197318
Journal
Journal of Forensic Sciences Volume: 47 Issue: 5 Dated: September 2002 Pages: 950-958
Date Published
September 2002
Length
9 pages
Annotation
This paper reports on a procedure that used inductively coupled plasma-atomic emission spectrometry (ICP-AES) to determine the concentrations of antimony, copper, tin, arsenic, silver, bismuth, and cadmium in lead alloys produced by two smelters and one ammunition manufacturer.
Abstract
Patterns of variations of bullet lead compositions within boxes of cartridges are well established. Less well known, however, are the effects that the various manufacturing processes have on the distribution of element concentrations among the leads produced. The goal of the current study was to monitor the homogeneity within melts of lead and to study the compositional profiles of several consecutive melts from individual producers. Two secondary smelters and an ammunition manufacturer provided specimens for this study. All specimens were analyzed by using ICP-AES. The results of the analyses of these samples show the variations in elemental composition in lead projectile products that result from several steps in typical manufacturing processes. The analysis of the samples from smelter 1 indicate that a variety of compositions were present in the products produced by a single smelter. Analysis of the samples from smelter 2 show that the compositional homogeneity was good within cast leads produced from a well-mixed kettle of molten lead. Consecutive pours without replenishment of a pot can produce tons of lead that has similar compositions, although in some cases distinguishable. The samples from the ammunition manufacturer displayed similar, although generally analytically distinguishable, compositions for the same alloy produced from different production runs, even when another alloy was produced in between. Thus, for any given evidentiary projectile, the forensic examiner can determine an approximate maximum number of potentially indistinguishable bullets by considering the manufacturing processes at the appropriate bullet manufacturing plant. 2 figures, 3 tables, and 35 references