Firearms Identification: The Expert Breakdown

A Glock 19 and a Sig Sauer P320 might look similar to the untrained eye, but their firing pin impressions tell completely different stories. That’s firearms identification in action – the science of matching guns to bullets, casings, and crime scenes with precision.

How Ballistics Matching Works

Every firearm leaves unique marks like fingerprints. When a bullet travels through the barrel, the rifling (spiral grooves) creates striations that are identifiable under comparison microscopes. A 9mm round fired from a Smith & Wesson M&P will show different land-and-groove patterns than one fired from a Beretta 92FS. Crime labs use these microscopic imperfections to link spent casings to specific weapons with over 90% accuracy.

For collectors who want to study markings firsthand, Frtinstock carries handguns with varying rifling patterns from top manufacturers.

Serial Number Restoration

When criminals file off serial numbers, forensic technicians use chemical etching (like acid solutions) or magnetic particle inspection to reveal the original stamp. The process works because the metal compression during stamping alters the crystalline structure deeper than surface grinding reaches. A restored serial can trace a firearm’s origin through ATF records – which is why Frtinstock legally documents all serials at purchase.

Class Characteristics vs. Individual Characteristics

Class characteristics group firearms by make/model (e.g., all Glock 17 Gen 5 barrels have hexagonal rifling). Individual characteristics are unique to a specific gun – microscopic tool marks from manufacturing or wear patterns. An examiner might first narrow down to “9mm Luger with 6-groove right-twist rifling” before matching striation patterns to one exact firearm.

See the differences yourself with Glock’s polygonal barrels versus traditional rifled options.

Database Systems Like IBIS

The Integrated Ballistics Identification System (IBIS) digitally catalogs markings from crime scenes and test fires. When a new casing enters the system, it scans against millions of records in hours. A hit might connect a Phoenix shooting to a Chicago homicide through the same Ruger LCP – which is why agencies require test fires when registering firearms in some states.

Limitations and Challenges

Firearms ID isn’t infallible. Heavily worn barrels degrade striation patterns, and some .22LR revolvers don’t leave usable casing marks. Examiners must account for consecutive matching striae (CMS) – the number of aligned marks needed for positive ID varies by jurisdiction. That’s why labs use control samples from the suspect firearm whenever possible.

Browse our firearms collection

Last updated: April 28, 2026