The Effect of Time on Rusted Firearm Identification

The Effect of Time on Rusted Firearm Identification

← Back to Firearm and Toolmarks Webinar Series

This webinar originally occurred on January 6, 2022
Duration: 1 hour


Since the development of early firearms in the mid-1200s, the best material for making critical parts for weapons has been iron-based metal. While iron and steel (an alloy metal that contains iron) are popular materials due to their strength and resilience, they are susceptible to chemical reactions when interacting with the environment. The most common chemical reaction of concern is corrosion or rust, which causes metal to deteriorate or dissolve. Corrosion and chemical reactions most often occur in wet and humid conditions. If firearms are not properly cared for or are left in these conditions, it could have adverse effects on the firearms’ operability and could affect the firearms’ individual characteristics.

While past research has been performed on the possibility of identifying characteristics on rusted firearms after they have been restored, there is little research on how long a firearm can be left to rust before an identification is no longer possible. Potential identification comparisons were performed on cartridge cases and projectiles after they were test fired through firearms that were left to rust for certain periods of time. This project evaluates the effects of rust on the common working surfaces of Glock and Smith & Wesson Sigma firearms that firearm examiners use to make an identification. The unpredictable data suggests that Glocks cannot be identified past three months of rusting while Sigmas can be identified at six months and possibly even longer.

Detailed Learning Objectives

  1. Attendees will learn the adverse effects of corrosion and rust on a firearm’s operability and individual characteristics.
  2. Attendees will learn the length of time a firearm, both with conventional and polygonal rifling, can rust before individual characteristics are altered or changed enough to where an identification can no longer be made.
  3. Attendees will learn whether the amount of time a firearm has been rusting can be estimated based on the condition in which it was found.


  • David Glatter | Forensic Firearms Examiner, Broward County Sheriff’s Office Crime Lab, Fort Lauderdale, Florida

Funding for this Forensic Technology Center of Excellence webinar has been provided by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice.

The opinions, findings, and conclusions or recommendations expressed in this webinar are those of the presenter(s) and do not necessarily reflect those of the U.S. Department of Justice.

Contact us at with any questions and subscribe to our newsletter for notifications.

Related Content

Evaluation of Purdue University’s 3D Imaging Prototype for Footwear and Tire Impressions

Date September 2022 Overview Supported by two National Institute of Justice (NIJ) awards (2016-DN-BX-0189 and 2019-R2-CX-0069), Dr. Song Zhang and his research team at Purdue University led the development of a fully automated 3D imaging system for footwear and tire…

2022 Update: 3D Imaging Technologies and Virtual Comparison Microscopy for Firearms Examination, A Landscape Study

Date August 2022 Overview The National Institute of Justice’s (NIJ) Forensic Technology Center of Excellence (FTCOE), led by RTI International, provides resources that promote the use of technologies in the forensic community. This report is an update to a 2016…

Guidelines for the Use of Terrestrial LiDAR Scanners in Criminal Justice Applications

Date March 2022 Overview Terrestrial LiDAR scanning devices (also known as terrestrial laser scanning devices, TLS) acquire complex geometric data that capture a three-dimensional representation of a scene; this technology is used in criminal justice applications such as documenting a…