Presenter Information

Jenna A. Campbell, B.A.*

Michael Van Stipdonk, Ph.D., Stephanie Wetzel, Ph.D., Det. Brian Kohlhepp, M.A.

Forensic Science & Law Program, Duquesne University, Pittsburgh, PA 15282, U.S.A.

Abstract

Gunshot residue (GSR) is a chemical reaction that occurs when a firearm is discharged, which emits a cloud of gases from the barrel of the gun. It consists of both the burned and unburned propellant and primer components. These components are either organic or inorganic in nature, respectively. The organic components are located in the gunpowder part of the bullet, while the inorganic components are located in the primer part of the bullet. The primer consists of lead, barium, and antimony. These elements are considered heavy metals. Additionally, lead, barium, and antimony are the three key elements found in the primer that characterize GSR. This study aimed to develop a method to differentiate among the inorganic components found in different types of ammunition used in a variety of firearms. Four types of firearms were used: a 20 Gauge Pardner SBI Shotgun; a .30-06 Ruger M77 Rifle; a .22 Ruger Super Single Six Revolver; and a 9 mm Beretta 92 FS Pistol. Each weapon was discharged five times for each of the four caliber and ammunition types. The ammunition consisted of 9mm, .22, .30-06, and 20 gauge calibers each for the four ammunition manufacturers, Federal Premium, Hornady, Remington, and Winchester. The right and left hands were tested for GSR by using aluminum stubs with a double-sided sticky carbon adhesive plating. The hands were stubbed starting with the dominant hand’s trigger finger, moving down towards the thumb. A control and blank were also analyzed. The control stub was used on a clean hand and the blank stub was solely the sticky carbon adhesive. The metallic components on each stub were optimally visualized and identified on the Scanning Electron Microscope coupled with an Electron Dispersive X-Ray Spectrometer (SEM-EDX). The results were examined by comparing the stub’s quantities and identities across each ammunition type. This study was significant in its ability to identify and quantify the metallic components of different ammunitions in various firearms. It can help narrow down the type of ammunition used, or even the type of firearm, that produced the specific GSR on the shooter’s hands. Even by quantifying the amount of GSR alone, it can help narrow down the specific firearm used, depending on the amount of GSR present. Eventually, a comprehensive database will be produced so that the forensic science community can benefit by enabling them to compare and contrast their own GSR results.

School

Bayer School of Natural and Environmental Sciences

Advisor

Michael Van Stipdonk, Ph.D.

Submission Type

Paper

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Analysis of Metallic Components of GSR from Various Types of Ammunition and Firearms Utilizing an SEM-EDX

Gunshot residue (GSR) is a chemical reaction that occurs when a firearm is discharged, which emits a cloud of gases from the barrel of the gun. It consists of both the burned and unburned propellant and primer components. These components are either organic or inorganic in nature, respectively. The organic components are located in the gunpowder part of the bullet, while the inorganic components are located in the primer part of the bullet. The primer consists of lead, barium, and antimony. These elements are considered heavy metals. Additionally, lead, barium, and antimony are the three key elements found in the primer that characterize GSR. This study aimed to develop a method to differentiate among the inorganic components found in different types of ammunition used in a variety of firearms. Four types of firearms were used: a 20 Gauge Pardner SBI Shotgun; a .30-06 Ruger M77 Rifle; a .22 Ruger Super Single Six Revolver; and a 9 mm Beretta 92 FS Pistol. Each weapon was discharged five times for each of the four caliber and ammunition types. The ammunition consisted of 9mm, .22, .30-06, and 20 gauge calibers each for the four ammunition manufacturers, Federal Premium, Hornady, Remington, and Winchester. The right and left hands were tested for GSR by using aluminum stubs with a double-sided sticky carbon adhesive plating. The hands were stubbed starting with the dominant hand’s trigger finger, moving down towards the thumb. A control and blank were also analyzed. The control stub was used on a clean hand and the blank stub was solely the sticky carbon adhesive. The metallic components on each stub were optimally visualized and identified on the Scanning Electron Microscope coupled with an Electron Dispersive X-Ray Spectrometer (SEM-EDX). The results were examined by comparing the stub’s quantities and identities across each ammunition type. This study was significant in its ability to identify and quantify the metallic components of different ammunitions in various firearms. It can help narrow down the type of ammunition used, or even the type of firearm, that produced the specific GSR on the shooter’s hands. Even by quantifying the amount of GSR alone, it can help narrow down the specific firearm used, depending on the amount of GSR present. Eventually, a comprehensive database will be produced so that the forensic science community can benefit by enabling them to compare and contrast their own GSR results.