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Firearms & Toolmarks Subcommittee

Members of the OSAC Firearms and Toolmarks Subcommittee
Members of the OSAC Firearms and Toolmarks Subcommittee (July 2019)

The Firearms and Toolmarks Subcommittee focuses on standards and guidelines related to the examination of firearm and toolmark evidence. This includes the comparison of microscopic toolmarks on bullets, cartridge cases, and other ammunition components and may also include firearm function testing, serial number restoration, muzzle-to-object distance determination, tools, and toolmarks.

Officers | Members | OSAC Registry Approved DocumentsDocuments In Process | Research & Development Needs | Discipline-Specific Baseline DocumentsPresentations


Todd Weller, Subcommittee Chair, Weller Forensics, LLC

Erica Lawton, Subcommittee Vice Chair, Alabama Department of Forensic Sciences

Wendy Gibson,  Executive Secretary, Virginia Department of Forensic Science


Cassey Allen, Texas Department of Public Safety (Austin, TX)

Carey M. Alvarez Bacha, Unified Metropolitan Forensic Crime Laboratory

Zachary Carr, Johnson County Sheriff's Office Criminalistics Laboratory

Eric Collins, Contra Costa County (California) Office of the Sheriff, Forensic Services Division

Jason Crafton, Missouri State Highway Patrol Crime Laboratory

William Demuth, II, Illinois State Police, Division of Forensic Services

Jules Epstein, Temple Beasley School of Law

Stefanie Happ, El Paso County Sheriff's Office

Ryan Lilien, M.D./Ph.D., Cadre Research Labs

Max Morris, Ph.D., Iowa State University

Rebecca Mullen, Arkansas State Crime Laboratory

Douglas Murphy, Terrorist Explosive Device Analytical Center (TEDAC), U.S. Federal Bureau of Investigation

Michael Neel, U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives

Melissa Oberg, Indiana State Police

Nicholas Petraco, John Jay College of Criminal Justice

Erich Smith, U.S. Federal Bureau of Investigation

Johannes A. Soons, U.S. National Institute of Standards and Technology

Xiaoyu Alan Zheng, U.S. National Institute of Standards and Technology

OSAC Registry Approved Documents

  • None currently.

Documents in Process

Under Development:

  • ASB 101, Supporting Documentation of Source Conclusions in Toolmark Examinations.
  • ASB 102, Guidelines for Peer Review of Source Conclusions in Toolmark Examinations.
  • ASB 103, Guidelines for Reporting of Source Conclusions in Toolmark Examinations.
  • ASB 104, Standard for 3D Virtual Comparison Microscopy for Firearm and Toolmark Analysis.
  • ASB 107, Best Practice Recommendation for Measuring Trigger Pull Measurements of a Firearm and Estimating its Uncertainty.

Work Product Sent to SDO:

SDO Published:

  • None currently.

Entered OSAC Registry Approval Process:

  • None currently.

Research & Development Needs

Discipline-Specific Baseline Documents

The Forensic Science Standards Board (FSSB) has provided the opportunity for OSAC Subcommittees to identify baseline documents and reference materials that best reflect the current state of the practice within their respective disciplines. 

These documents contain practical information regarding these disciplines that can help forensic scientists, judges, lawyers, researchers, other interested parties and the general public, to better understand the nature, scope, and foundations of the individual disciplines as they are currently practiced.

It is important to note that the identification of these documents in this venue does not represent an endorsement by OSAC or NIST.  Only documents that are posted on the OSAC Registries constitute OSAC endorsement. All copyrights for these documents are reserved by their owners. Subcommittee position statements or responses to data collections by the subcommittee represent the consensus opinion of the subcommittee, not necessarily the position of the entire OSAC organization or NIST.

OSAC Firearms and Toolmarks Subcommittee's Response to the President’s Council of Advisors on Science and Technology's (PCAST) Request for Additional References - Submitted December 14, 2016

OSAC Firearms & Toolmarks Subcommittee's Response to the President’s Council of Advisors on Science and Technology's (PCAST) Request for Information – Submitted December 23, 2015

SWGGUN Guidelines for Barrel and Overall Length Measurements for Firearms

SWGGUN Guidelines for Criteria for Identification

SWGGUN Guidelines for Developing a Training Manual

SWGGUN Guidelines for Documentation of the Examination of Tools and Toolmarks

SWGGUN Guidelines for Documentation of the Examination of Ammo and Ammo Components

SWGGUN Guidelines for Elimination Factors Related to FA-TM Examinations

SWGGUN Guidelines for Forensic Examination Guidelines for Silencers

SWGGUN Guidelines for Gunshot Residue Distance Determinations

SWGGUN Guidelines for Projectile Path Reconstruction-Essential Elements 

SWGGUN Guidelines for the Documentation of Firearm Examinations 

SWGGUN Guidelines for the Standardization of Comparison Documentation

SWGGUN Guidelines for Trigger Pull Analysis

SWGGUN Minimum Qualifications for Experienced Firearm and Toolmark Examiners

SWGGUN Minimum Qualifications for Firearm and Toolmark Examiner Trainees

SWGGUN Code of Ethics

SWGGUN Foundational Report

SWGGUN Quality Assurance Guidelines

SWGGUN Response to RDT&E

SWGGUN Systemic Report

SWGGUN Transition from ASCLD-LAB Legacy to ISO-IEC 17025​​​​​​


In general, the development of standards and guidelines is transitioning from the Scientific Working Groups (SWGs) to the OSAC. Some SWGs will continue to operate to provide other resources within their discipline. The existing SWG documents will remain in effect until updated documents are disseminated by the OSAC or the SWG. SWGDAM will retain the responsibility for updating the FBI DNA Quality Assurance Standards.

– Forensic Science Standards Board: March 2015

Created June 27, 2014, Updated December 10, 2019