Terry Molly, Fookes Barry, Bridge Candice M
National Center for Forensic Science, University of Central Florida, PO Box 162367, Orlando, FL, 32816-2367, USA.
Forensic Sci Int. 2017 Jul;276:51-63. doi: 10.1016/j.forsciint.2017.04.015. Epub 2017 May 1.
Ammunition is typically composed of a lead-based priming mixture which contributes to the characteristics most commonly used for the identification of gunshot residue (GSR). Due to the health risks often associated with lead, the use of lead-free primers in ammunitions is becoming more popular. Thus, the presence of GSR is becoming more difficult to discern based on the traditional means, i.e. the presence of lead (Pb), barium (Ba), and antimony (Sb). While research has been conducted on the differences between lead-based and lead-free muzzle discharge residue, few have researched other components of ammunition which may lead to other means of characterizing GSR. This research, therefore, covers that gap by focusing on the priming cup present in ammunition and the residue which may originate from it, that can contribute to muzzle discharge residue. In this study, a lead-based and a lead-free ammunition from four different manufacturers were chosen. The cartridges were fired using a Glock 17, 9mm Parabellum, collected post-fire, and subsequently de-primed resulting in the removal of the anvil. The GSR present on the anvils and cups was analyzed using scanning electron microscopy coupled with energy dispersive x-ray spectrometry (SEM-EDX). The data was then processed using unit vector analysis for normalization and analyzed using principal component analysis (PCA) and linear discriminant analysis (LDA). This data was then used to determine the components of the cartridge case which contribute to GSR and develop a method of characterization between lead-free and lead-based ammunition. Such a method will improve the detection of GSR by strengthening the criteria of identification.
弹药通常由含铅的起爆混合物组成，这种混合物决定了最常用于识别枪击残留物（GSR）的特征。由于铅通常存在健康风险，弹药中使用无铅引物正变得越来越普遍。因此，基于传统方法，即根据铅（Pb）、钡（Ba）和锑（Sb）的存在来辨别GSR变得越来越困难。虽然已经对含铅和无铅枪口排出残留物之间的差异进行了研究，但很少有人研究弹药的其他成分，这些成分可能导致其他表征GSR的方法。因此，本研究通过关注弹药中存在的起爆药杯及其可能产生的残留物来填补这一空白，这些残留物可能导致枪口排出残留物。在本研究中，选择了来自四个不同制造商的含铅和无铅弹药。使用格洛克17型9毫米帕拉贝鲁姆手枪发射子弹，射击后收集，随后去除底火，从而移除砧座。使用扫描电子显微镜结合能量色散X射线光谱法（SEM-EDX）分析砧座和药杯上的GSR。然后使用单位向量分析对数据进行归一化处理，并使用主成分分析（PCA）和线性判别分析（LDA）进行分析。然后利用这些数据确定弹壳中对GSR有贡献的成分，并开发一种区分无铅和含铅弹药的表征方法。这种方法将通过加强识别标准来改进GSR的检测。
