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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.

News and Updates

Texas Forensic Science Commission Supports NIST Recommendations

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

Blog Posts

Building a Firearms Toolmark Database

Got Evidence? How to Improve Forensic Science

Feature stories and explainers

Preserving the Kennedy Assassination Bullets in Digital Form

View firearms and toolmarks publications View firearms and toolmarks research projects

Featured Videos

Preserving the JFK Assassination Bullets

Preserving the JFK Assassination Bullets

Forensic Marks on a Cartridge Case

Forensic Marks on a Cartridge Case

Matching Crime-Scene Bullets Segment by Segment

Matching Crime-Scene Bullets Segment by Segment

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