Unlike human fingerprints, a gun's "fingerprint" changes over time. Every shot fired slightly alters the microscopic striations in the barrel. Experts may only fire a limited number of test rounds because the fifth shot might already look different from the first. 2. Success Rates and "Expensive Failures"
When a gun is fired, several mechanical actions leave distinct impressions on the ammunition. These marks are primarily categorized into two types: 1. Striation Marks (on the bullet)
: When the gun fires, the casing is forced backward against the breech face, transferring its texture to the metal. bullet fingerprinting
Despite its usefulness, "bullet fingerprinting" is not always a definitive proof of guilt. Several factors can complicate or even invalidate a match. 1. Barrel Evolution
: The pin strikes the primer at the back of the casing, leaving a unique indentation. Striation Marks (on the bullet) : When the
Bullet fingerprinting, more formally known as , is a forensic technique used to match a fired bullet or shell casing to a specific firearm. The "fingerprint" consists of unique, microscopic marks left on the ammunition by the gun's internal components during the firing process. While often portrayed as a flawless investigative tool in television dramas, the reality of its scientific reliability is a subject of significant debate within the forensic community. How It Works: The Mechanical Fingerprint
: Microscopic flaws in the manufacturing process or wear and tear from use create a "signature" unique to that specific barrel. 2. Impression Marks (on the casing) The "fingerprint" consists of unique
To manage these vast amounts of data, law enforcement uses specialized databases and imaging systems.