A Worldwide Study of Bullets Fired From 10 Consecutively Rifled 9MM RUGER Pistol Barrels-Analysis of Examiner Error...

Area of Science:

• Forensic Science
• Ballistics
• Firearms Examination

Background:

• A continuing study initiated over twenty years ago by Brundage et al. investigates the accuracy of firearms examiners.
• The research focuses on the ability to associate fired bullets with the specific barrels through which they were fired.

Purpose of the Study:

• To update and report on the results of an ongoing "10-barrel test" assessing forensic firearms examiners' proficiency.
• To quantify the error rates in bullet-barrel association by firearms examiners.

Main Methods:

• Utilized data from 697 participants and over 240 test sets involving bullets fired from 10 consecutively rifled RUGER P-85 pistol barrels.
• Employed a Bayesian approach to analyze the collected data.
• Assigned posterior average examiner error rates using vague prior information.

Main Results:

• The study reports on the cumulative results of this decades-long investigation.
• The most conservative value for the average examiner error rate was determined.
• A posterior mean error rate of 0.053% was calculated, with a 95% probability interval of [1.1 × 10^-5 %, 0.16%].

Conclusions:

• The findings provide a statistically robust assessment of firearms examiner accuracy in bullet-barrel comparisons.
• The low calculated error rate suggests a high degree of reliability in the field of firearms examination.
• This ongoing study contributes valuable data to the understanding of forensic firearms analysis capabilities.