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The lead-in method for bullet impacts in metal panels
1ai2-3D Forensics, Vaughan, Ontario L4L 8A4, Canada.
Forensic Science International
|August 1, 2021
Summary
The lead-in method for determining bullet trajectory at shooting scenes is less studied. This research defines and tests its accuracy, finding characteristic error curves for different calibers and ammunition types.
Area of Science:
- Forensic Science
- Ballistics
- Crime Scene Investigation
Background:
- Trajectory rods are standard for documenting bullet paths but fail on thin materials.
- Elliptical and lead-in methods are alternatives, but the elliptical method struggles with deformed impacts, and the lead-in method is less understood.
Purpose of the Study:
- To define the lead-in method for bullet trajectory analysis.
- To test the performance and accuracy of the lead-in method using blind participants and various calibers/ammunition.
Main Methods:
- Defined the lead-in method for trajectory analysis.
- Conducted tests with 15 blind participants, 5 calibers, and 2 ammunition types per caliber.
- Analyzed the characteristic error curves associated with each caliber/ammunition combination and impact angle.
Main Results:
- Each caliber and ammunition combination exhibited a unique error curve that varied with impact angle.
- Errors were not constant and could exceed 20 degrees.
- Higher angles of incidence resulted in greater error ranges due to a smaller lead-in area.
Conclusions:
- The lead-in method's accuracy is dependent on caliber, ammunition, and impact angle.
- The study provides a proposed method of use, limitations, and accuracy insights for the lead-in technique.
- Further research is needed to refine the lead-in method for broader application in forensic ballistics.
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