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Firearms and toolmarks


What is forensic ballistics? Forensic ballistics involves the examination of evidence from firearms that may have been used in a crime. When a bullet is fired from a gun, the gun leaves microscopic marks on the bullet and cartridge case. These marks are like ballistic fingerprints. If investigators recover bullets from a crime scene, forensic examiners can test-fire a suspect’s gun, then compare the marks on the crime scene bullet to marks on the test-fired bullet. The examiner will then assess how similar the two sets of marks are and determine if the bullets are likely to have been fired from the same gun or different guns. Cartridge cases are compared in the same way.

What we do

For roughly a century, forensic ballistics experts have been comparing bullets and cartridge cases by visually examining them under a split-screen microscope. After comparing the bullets, the examiner can offer an expert opinion as to whether they match but cannot express the strength of the evidence numerically. NIST scientists are developing methods that will allow an examiner to attach an objective, statistically meaningful measure of certainty to their testimony. We also produce the NIST Standard Bullet and the NIST Standard Cartridge Case. These aren’t real bullets or cartridge cases, but precisely manufactured replicas of fired bullets and cartridge cases with known ballistic fingerprints. Crime labs use these standards to calibrate their instruments, which helps ensure that their examinations produce accurate results.

Featured Content

The Research

Projects & Programs

NIST Ballistics Toolmark Database

The NIST Ballistics Toolmark Research Database is an open-access research database of bullet and cartridge case toolmark data. This database will: foster the

Statistics for Ballistics Identification

NIST is making advances in the science and technology for identification of firearms and tool marks; SED provides statistical analyses and designs as a vital


How Good a Match is It? Putting Statistics into Forensic Firearms Identification

On February 14, 1929, gunmen working for Al Capone disguised themselves as police officers, entered the warehouse of a competing gang, and shot seven of their rivals dead. The St. Valentine’s Day Massacre is famous not only in the annals of gangland history, but also the history of forensic science. Capone denied involvement, but an early forensic scientist named Calvin Goddard linked bullets from

Two New Forensic Firearm Examination Standards Added to the OSAC Registry of Approved Standards

NIST Launches an Updated Organization of Scientific Area Committees for Forensic Science

Divide and Conquer: New Algorithm Examines Crime-Scene Bullets Segment by Segment

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