Striations
Definition
Fine parallel scratches on a fired bullet's surface, produced by asperities on the barrel's land surfaces. Each striation reflects the surface topography of the barrel at a specific location.
- Cause
- Asperities on barrel land surfaces
- Records
- Barrel surface topography at that point
- Comparison tool
- Comparison microscope
- Location
- Fired bullet surface
Common questions
What does an examiner look for under the comparison microscope?+
A consecutive matching sequence of striae, meaning a run of ridges and valleys on the questioned bullet that lines up with the same sequence on a known test-fired bullet, judged against the examiner's training and established sufficiency criteria.
Why do land and groove striations get analysed separately?+
Each land and groove engraving on the bullet corresponds to a distinct region of the barrel's bore, so examiners compare each engraved area independently, which increases confidence when multiple areas each show a consistent pattern.
Related terms
- AFTE Theory of Identification
- The Association of Firearm and Tool Mark Examiners' standard (1992, revised 2011) for reporting tool-mark comparison conclusions as Identification, Inconclusive, or Elimination...
- BalliScan 3D
- Foster and Freeman's three-dimensional topographic bullet comparison instrument that maps striated surfaces using structured-light interferometry for both optical and digital comparison workflows.
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Comparison Microscope
- Two compound microscope bodies connected by an optical bridge that presents one half of each body's image in a single split eyepiece...
- Consecutive Matching Striae (CMS)
- A run of adjacent, individually corresponding striae observed across two bullets in the comparison microscope split field. The length of the longest...
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
- Leica FSC
- Leica Forensic Comparison System; a motorised zoom comparison microscope used in firearms and toolmark examination at CFSL laboratories in India, European national...
- PCAST Report (2016)
- The President's Council of Advisors on Science and Technology 2016 report on forensic science that found firearms mark analysis had not yet...
- Projectina PAG II
- A high-precision Swiss comparison microscope with motorised stages and quantitative striation-angle measurement, used at Swiss cantonal forensic labs and German LKA laboratories.