Semester

Summer

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Forensic and Investigative Science

Committee Chair

Keith B Morris

Committee Member

Jamie S Spaulding

Committee Member

Tina Moroose

Abstract

Firearms examination has been a mainstay of Forensic Science for over a century. One of the principal assessments performed by firearm examiners is the comparison of fired projectiles to a suspect firearm. The AFTE theory of identification, as it pertains to firearms and toolmarks, supports the basis that the barrel of a firearm will impart class and individualizing characteristics onto the fired projectile. The characteristics are developed by the interaction of the projectile surface with the lands of the barrel. Features on the lands, which are incidental to the process of manufacturing, dictate the characteristics observed on the fired projectile. There is also a general opinion that features on lands around the muzzle of the barrel impart majority of the striations seen on fired projectiles, as it is the last point of contact. While there have been many studies looking at individualizing characteristics on fired projectiles, no other study to the best of our knowledge has been conducted to address this opinion nor to understand the location and distribution of features within a barrel. The aim of this study was to identify the features on the lands within the barrels of three 9 mm pistols that impart striations on fired projectiles and understand the general spread of those features. The barrels of these three firearms were rifled with three different manufacturing techniques, broach, button, and hammer forge rifling. Additionally, each of the three firearm barrels were cast in triplicate and the topographies of these casts were captured via confocal microscopy. Within this exploratory data set, it has been shown that potential contributing features were found along the entire length of all three barrels, contradicting the general opinion that these potential contributing features would be clustered near the muzzle. Though these results require further validation this study still provides useful foundational information to firearm examiners. The findings of this study also aid the validity of performing comparisons between fired projectiles and suspect firearms where part of barrel has been sawn off.

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