OSAC 2021-N-0012 Requirements and 

Recommendations for a Firearm and

Toolmark Examiner Training Program

1

OSAC 2021-N-0012 

Requirements and 

Recommendations for a 

Firearm and Toolmark 

Examiner Training Program

Firearm and Toolmark Subcommittee

Physics/Pattern Interpretation Scientific Area Committee

Organization of Scientific Area Committees (OSAC) for Forensic Science
OSAC 2021-N-0012 Requirements and 

Recommendations for a Firearm and

Toolmark Examiner Training Program

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OSAC Proposed Standard

Requirements and Recommendations for 

a Firearm and Toolmark Examiner 

Training Program

Prepared by 

Firearms and Toolmark Subcommittee

Version: 1.0

August 2022

Disclaimer:

This OSAC Proposed Standard was written by the Organization of Scientific Area Committees (OSAC) for Forensic 

Science following a process that includes an open comment period. This Proposed Standard will be submitted to a 

standards developing organization and is subject to change.

There may be references in an OSAC Proposed Standard to other publications under development by OSAC. The 

information in the Proposed Standard, and underlying concepts and methodologies, may be used by the forensicscience community before the completion of such companion publications.

Any identification of commercial equipment, instruments, or materials in the Proposed Standard is not a 

recommendation or endorsement by the U.S. Government and does not imply that the equipment, instruments, or 

materials are necessarily the best available for the purpose.

Keywords: Firearm and Toolmark Examination, Firearm and Toolmark Examiner, Training
OSAC 2021-N-0012 Requirements and 

Recommendations for a Firearm and

Toolmark Examiner Training Program

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Foreword

The following standard identifies the training requirements to become a qualified firearm and 

toolmark examiner.

This standard was proposed by the Firearms and Toolmarks Subcommittee of the Organization of 

Scientific Area Committees (OSAC).

This document is intended to provide requirements and recommendations for firearm and

toolmark examiner training programs.
OSAC 2021-N-0012 Requirements and 

Recommendations for a Firearm and

Toolmark Examiner Training Program

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Acknowledgements

Drafting Working Group Members:

Jason Crafton Missouri State Highway Patrol

William E. Demuth II Illinois State Police

Jodi Marsanopoli Bureau of Alcohol, Tobacco, Firearms and Explosives

Doug Murphy Federal Bureau of Investigation

Melissa Oberg Indiana State Police

Kevin Rippman Bureau of Alcohol, Tobacco, Firearms and Explosives

Jacob Seror Los Angeles Police Department

Carey Alvarez Bacha Unified Metropolitan Forensic Crime Laboratory
OSAC 2021-N-0012 Requirements and 

Recommendations for a Firearm and

Toolmark Examiner Training Program

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Table of Contents

1 Introduction 6

2 Scope 6

3 Normative References

6

4 Terms and Definitions 6

5 Requirements 8

6 Optional Topics 21

Bibliography 24
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Recommendations for a Firearm and

Toolmark Examiner Training Program

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1 Introduction

1.1 This document has been developed with the objective of improving the quality and 

consistency of firearm and toolmark examination training practices.

1.2 This document contains an outline of training topics which serve as minimum requirements 

for firearm and toolmark examiner training programs. The requirements listed in this standard 

include the essential skills and knowledge needed to perform successfully in the discipline.

1.3 The additional recommended topics are considered by the subcommittee to be highly 

beneficial and worthy of inclusion should the necessary resources be available. These 

recommended topics will be explicitly identified as such. 

1.4 The Forensic Science Services Provider (FSSP) shall determine the required and 

recommended reading for the topics that are provided in the document. The recommended source 

for the references is the Association of Firearm and Tool Mark Examiners (AFTE) Training Manual. 

The AFTE Training Manual is periodically updated and will provide the best source material for the 

various training topics.

 

2 Scope

This document provides the minimum requirements and recommendations for a firearm and 

toolmark examiner training program. Requirements and recommendations include training topics, 

documentation, casework exercises, and methods for testing competency. The FSSP shall provide 

training objectives, training manuals, and training assignments. This standard does not preclude 

agencies from incorporating additional mission-specific requirements.

3 Normative References

none

4 Terms and Definitions

4.1 Competency Test

A test that demonstrates that a forensic science practitioner has acquired and demonstrated 

specialized knowledge, skills, and abilities (KSAs) in the standard practices necessary to conduct 

examinations in a discipline or category of testing prior to performing independent casework.
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4.2 Firearm and Toolmark Examination

A discipline of forensic science charged with conducting comparison examinations of tools and 

toolmarks and reporting the conclusion. When the tool is a firearm, the discipline also seeks to 

answer relevant questions about the firearms or ammunition components involved in an incident.

4.3 Firearm Examination

A specialized type of firearm and toolmark examination that includes, but is not limited to, the 

classification and comparison of microscopic toolmarks created by firearms on ammunition 

components. It may also include the examination of firearms, serial number restoration, and 

muzzle-to-target distance determinations.

4.4 Firearm and Toolmark Examiner

A person who has completed training in the discipline of firearm and (non-firearm) toolmark 

examinations and is currently authorized to perform work in these categories of testing at a 

particular forensic science service provider.

4.5 Qualified Firearm Examiner 

A person who has completed training in the discipline of firearm examinations and is currently 

authorized to perform work in this category of testing at a particular forensic science service 

provider.

4.6 Forensic Science Services Provider (FSSP)

A forensic science agency or forensic science practitioner providing forensic science services.

4.7 Known Same Source (KSS)

Toolmarks or specimens known to have been made by the same tool. 

4.8 Known Different Source (KDS)

Toolmarks or specimens known to have been made by different tools or different working surfaces 

of the same tool.

4.9 Qualified Toolmark Examiner 

A person who has completed training in the discipline of (non-firearm) toolmark examinations and 

is currently authorized to perform work in this category of testing at a particular forensic science 

service provider.

4.10 Toolmark Examination

A specialized type of firearm and toolmark examination that includes the classification and 

comparison of microscopic toolmarks created by non-firearm tools. It may also include the 

examination of non-firearm tools.

4.11 Trainee

A person who is undergoing, but has not yet completed, training in the disciplines of firearm and/or 

toolmark examination.

Refer to the Minimum Education Requirements for Firearm and Toolmark Examiner Trainees 

document.
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Recommendations for a Firearm and

Toolmark Examiner Training Program

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4.12 Trainer 

Instructors who encompass various topics inside or outside of the discipline and should be selected 

based on their relevant experience in that subject area (i.e - firearm examiner, statisticians, 

armorers, and other subject matter experts).

4.13 Training Coordinator

A person who is responsible for delivering or monitoring training, or verifying the successful 

completion of training elements. This person may be a currently qualified or formerly qualified 

examiner with appropriate expertise who has been authorized by the forensic science service 

provider to perform training-related duties. 

Duties may include, but are not limited to, developing curriculum, delivering training materials, 

overseeing performance of the trainee, and giving final approval of the training program. The 

training coordinator may also be the trainer or be a separate individual(s).

5 Requirements

5.1 Administrative

5.1.1 Documentation

A document describing all training requirements and trainee expectations shall be issued to the 

trainee at the beginning of the training period. This document shall contain information regarding 

the training topics that will be covered, the expected timeline of their completion, and the various 

types of tests that the trainee must successfully complete. The completion of all required elements 

of training shall be documented and retained as recommended by the FSSP.

5.1.2 Required Elements

Trainees being trained in firearms, but not toolmarks, shall complete sections 5.1, 5.2.1 - 5.2.11, 

5.2.14 - 5.2.19. 

Trainees being trained in toolmarks, but not firearms, shall complete sections 5.1, 5.2.1, 5.2.3, 5.2.4, 

5.2.8, 5.2.12 - 5.2.19.

Trainees being trained in both firearms and toolmarks shall complete sections 5.1, 5.2.1 - 5.2.19. 

The requirements for total KSS and KDS comparisons shall not be reduced based upon categories of 

training.

Trainees being trained in distance determinations (6.1, 6.2), serial number restorations (6.3), and 

fracture examinations (6.4) or shall also complete the corresponding requirements for those 

categories.

5.1.3 Training Topics Not Present

The absence of a particular knowledge area or skill in the training topics listed below is not 

necessarily intended as an objection to its inclusion in a training plan. FSSPs should add any 

training topics that are relevant and beneficial.
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Toolmark Examiner Training Program

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5.1.4 Training Methods

For most topics, this document does not endorse particular learning methods. It is the 

responsibility of each FSSP to determine the most effective approach for training each individual. A 

successful training program includes readings, lectures, demonstrations, discussions, examinations 

under the guidance of a qualified examiner, and practical exercises incorporating firearms/tools, 

toolmarks, and comparison techniques. The order of the topics listed in this document is not 

intended to be the recommended order of training. Many of the topics are interrelated and do not 

necessarily need to be taught separately. 

5.1.5 Testing

Assessment tools for the various training topics may include, but are not limited to: written tests, 

oral examinations, mock casework, practical exercises/examinations (comparisons), presentations, 

and mock trials. 

Answers to the written tests, questions in oral examinations, intercomparison tests, mock 

casework, and practical examinations shall be known by the FSSP prior to the tests being 

administered. Standards for successful completion of these tests shall be clearly defined by the 

FSSP and provided to the trainee prior to the test being administered.

Presentations and mock trials shall be evaluated according to the FSSP standards and the 

evaluations shared with the trainee upon conclusion. 

Competency testing shall be performed with realistic casework elements including case notes, 

comparison examinations, and written reports. A competency test shall be successfully completed 

in each sub-discipline prior to assuming casework in that specific sub-discipline.

Successful completion of all assigned topics in the training program shall be required. It is the 

responsibility of each FSSP to provide the assessment of the trainee and also the pass/fail 

determination for the test methods they so choose. 

If the trainee does not obtain a satisfactory score on any test, the FSSP shall provide training 

directed toward the observed deficiencies, followed by retesting.

5.1.6 Mentored Casework

Prior to performing independent casework, the new examiner shall participate in a period of 

mentored casework. Mentorship shall include actual or simulated casework and should focus on 

the depth and breadth of cases routinely encountered by the laboratory as determined by the FSSP. 

The new examiner’s trainer, or other qualified examiner may observe and assist the new examiner 

as needed and shall perform a documented review of all casework including a microscopic review 

of all comparison conclusions. The FSSP shall determine the duration of mentored casework and 

the criteria for successful completion. 

5.1.7 Evaluation of Training Program
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Toolmark Examiner Training Program

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The FSSP shall establish a formal mechanism for trainees to provide feedback on the effectiveness 

of the training program. This information shall be used by the FSSP to evaluate, update and improve 

the training program on a periodic basis.

5.1.8 Continuing Education

After completion of training, examiners shall engage in a minimum of forty hours per year of 

discipline-specific continuing education (e.g. attending conferences, participating in research, 

visiting manufacturing facilities, reviewing literature, attending workshops, publishing peer 

reviewed research projects) FSSPs shall dedicate the necessary resources to ensure compliance. 

The FSSP shall determine what qualifies as discipline-specific continuing education and how to 

document compliance. 

5.2 Training Topics

5.2.1 General Manufacturing and Machining

Understanding general manufacturing and machining processes, especially as they pertain to the 

production of firearms and tools, is of fundamental importance. This understanding will allow the 

trainee to assess the significance of the toolmarks encountered during initial examinations, during 

comparison examinations, and when rendering source conclusions.

The following subject areas shall be included in a training program:

Gross Forming Techniques

Forging

Hand

Drop

Press

Hammer

Casting

Sand

Investment/Lost Wax

Fine Forming Techniques

Turning

Milling

Drilling

Boring

Reaming

Broaching

Sawing

Electrical discharge machining (EDM)

Electrochemical machining (ECM)

Metal injection molding

Finishing Techniques

Grinding/Sanding

Etching

Media blasting

Tumbling media

Finishes

Bluing
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Toolmark Examiner Training Program

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Browning

Oxide (Parkerizing, etc.)

Plating

Coatings/Paint

Key Machining Concepts for Toolmark Identification

Chip formation

Plastic deformation

Tool wear

Built Up edge

The following subject areas should be included in a training program:

Tours of machine shops or manufacturers, supplemental to any other firearm, ammunition 

or tool manufacturer tours, to ensure sufficient exposure to manufacturing/machining 

methods listed above

General concepts and practices of Additive Manufacturing (e.g. 3-D printing)

5.2.2 Firearms Manufacturing

In addition to general manufacturing techniques, an understanding of the specific manufacturing 

and machining processes that pertain to the production of firearms and firearm parts will assist the 

trainee in understanding both the design concepts and the function of firearms. Additionally, an 

understanding of the common machining methods used for barrels, breech faces, and other 

surfaces that contact ammunition components will allow the trainee to understand the sources and 

nature of toolmarks present on fired and unfired ammunition components.

The following subject areas shall be included in a training program:

Barrels

Blanks

Deep hole drilling

Reaming

Extrusion (Hi-Point)

Rifling

Button

ECM

EDM 

Gang Broach

Hammer Forged

Single Point/Hook/Scrape Rifling

Finishing

Straightening

Chambering

Throating

Crowning

Contouring

Honing/Lapping/Polishing

Common machining techniques that are used to produce the following parts:
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Toolmark Examiner Training Program

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Breech faces

Chambers

Hammers/Firing pins/Strikers

Firing pin aperture

Extractors

Ejectors

Feed ramps / forcing cones

Magazines

Ejection port

Common alterations and associated toolmarks

Sawed off barrel

Muzzle attachments

Front sight alteration

The following subject areas should be included in a training program:

Tours

Firearm Manufacturers 

Barrel Manufacturers

5.2.3 Legal History of Firearm and Toolmark Examinations

An understanding of the legal context of firearm and toolmark examinations requires knowledge of 

the evolution of firearm and toolmark practice and testimony in courts of law, as well as applicable 

laws regarding the use of certain firearms and accessories. Recommended articles and references 

can be located in the AFTE Training Manual. 

5.2.4 Theory and Validity of Firearm and Toolmark Examinations

The successful application of examination techniques and any subsequent communication 

regarding the results of examinations require a complete understanding of the scientific foundation 

of firearm and toolmark examinations. Theory, nomenclature, research, and statistical methods are 

all crucial to successful completion of training. Recommended articles and references for the below 

subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

AFTE Theory of Identification

Class characteristics

Subclass characteristics

Individual characteristics

Types of Toolmarks

Impressed Toolmarks

Striated Toolmarks

Concept of Known Same Source Toolmark (KSST) and Known Different Source Toolmark (KDST) 

comparisons

Research

Validity Testing

Early studies
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Toolmark Examiner Training Program

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Black, White, and Gray box studies

Error Rates

Expressions of Confidence

Criticisms of Current Methods

Basic concepts of Quantitative Consecutive Matching Stria (QCMS)

The following subject areas should be included in a training program:

Statistics, including likelihood ratios

Toolmark topography instruments and correlation algorithms

5.2.5 Ammunition

Successful examinations of both fired and unfired ammunition components require knowledge of 

industry terminology, the evolution of ammunition designs, and manufacturing methods associated 

with ammunition. Recommended articles and references for the below subject areas can be located 

in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Ammunition manufacturing

Blanking

Cupping

Drawing

Swaging

Punching/Headstamps

Case/primer materials

Assembly

Crimping

Reloading

Terminology associated with both historic and modern ammunition

Caliber naming conventions

Cartridge case design

Terminology associated with shotshell ammunition

Components

Gauge

Pellet sizes

Slug designs

Caliber determination of bullets

Instrumentation used

Caliber determination of cartridges/cartridge cases

Headstamps

Case dimensions

Caliber families

Mismatching and Interchangeability of ammunition and firearm caliber

Wildcat cartridges
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Evolution of ammunition

Propellants, black powder to modern smokeless powder

Rimmed and centerfire 

Types of primers

Bullet shapes, designs 

Current common brands and types of ammunition 

The following subject areas should be included in a training program:

Tours of ammunition factories

Manufacturing toolmark examinations and comparisons (e.g. bunter marks, mold marks), 

including interpretation limitations

5.2.6 Firearm Design and Terminology

The successful examination of firearms requires comprehensive knowledge of terminology, 

evolution of design concepts, firearm parts, and the cycle of operation of firearms. Recommended 

articles and references for the below subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Evolution of Firearms

Ignition Systems

Safeties

Firearms Terminology

Pistol

Revolver

Rifle

Shotgun

Parts and nomenclature associated with types of firearms

Assembly and disassembly of firearms, supplemented with owner’s manuals, books and 

videos 

Cycle of fire

Action types 

Break Action

Bolt action

Lever action

Pump action

Revolver

Semi-Automatic/Automatic Actions

Blowback

Recoil

Gas operated

Modes of Fire

Single Action

Double Action

Burst/Fully Automatic

Post manufacture alterations and accessories 

Full Auto conversions
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Incomplete firearms (“80%” firearms, receiver blanks, home-built)

Drop-in barrels

Bump stocks

Trigger modifications

5.2.7 Examination of Firearms

In addition to design and terminology, examiners must know the common examination techniques 

that are required for a full analysis and documentation of a firearm’s design and functional 

characteristics. This must be coupled with safe handling and firing practices and knowledge of the 

source of important toolmarks within each firearm and any associated accessories. Recommended 

articles and references for the below subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training plan:

Safe handling and firing of firearms

Function Examinations

Firearm safety/recall list

Selection and test firing of appropriate ammunition

Safety tests

Trigger Pull

Barrel and overall length measurements

Impact test

Casting of firearm parts/alternate tools for creating test marks

Firearms Laws

NFA (National Firearms Act)

GCA (Gun Control Act)

Relevant State/Local Specific Laws

Firearm components that potentially create toolmarks:

Lands and grooves

Breech / bolt face

Firing pin

Ejector

Ejection port

Extractor

Chamber

Feed ramp

Barrel extension

Magazine

Evaluation of potential for subclass characteristics in each of the categories above.

5.2.8 Microscope Use and Familiarization

Microscopes are the primary tools with which firearm and toolmark examiners conduct 

examinations of fired ammunition components and toolmarked surfaces. Recommended articles 

and references for the below subject areas can be located in the AFTE Training Manual. 
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Recommendations for a Firearm and

Toolmark Examiner Training Program

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The following subject areas shall be included in a training program:

Design and use of a stereoscope

Design and use of a comparison microscope

Light sources and lighting techniques

Photographic techniques

Comparison techniques

The following subject areas should be included in a training program:

Focus variation microscopy

Interferometric microscopy

Confocal microscopy

Photometric microscopy

Virtual comparison microscopy

5.2.9 Bullet Examinations

Bullets, when fired through the barrel of a firearm, acquire surface features from the internal 

surfaces of the barrel. Accurate examinations of these characteristics are essential. Additional 

knowledge of rifling characteristics and bullet design may also allow the examiner to eliminate 

certain classes of firearms from any association with the fired bullet. Recommended articles and 

references for the below subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Caliber determination

Design features

Direction of twist

Land and groove impression measurement techniques

General Rifling Characteristics (GRC) database

Recognition of potential subclass characteristics in both barrels of firearms and areas on bullets

Evaluation and comparison of test fired bullets and selection of appropriate ammunition

Evaluation and comparison of questioned bullets

Range of conclusions for bullet comparisons

Documentation of examination results and comparisons

5.2.10 Cartridge/Cartridge Case/Shotshell Examinations

Cartridge cases and shotshells, when fired in a firearm, acquire characteristics from the working 

surfaces of that firearm. Accurate examinations of these characteristics are essential. Additional 

knowledge of cartridge/shotshell design allows the examiner to eliminate certain classes of 

firearms from any association with the ammunition component. Recommended articles and 

references for the below subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Recognition of marks on cartridges/cartridge cases/shotshells
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Firing pin impression

Breech face marks

Aperture impression/shear

Extractor

Ejector

Ejection port marks

Firing pin drag

Chamber marks

Barrel extension marks

Magazine lip marks

Loaded chamber indicator impressions

Shell stop marks

Anvil Marks

Caliber/gauge determination

Design features

Recognition of potential subclass marks on fired cartridge cases/shotshells

Recognition of manufacturing marks

Evaluation and comparison of test fired cartridge cases/shotshells and selection of appropriate 

ammunition

Evaluation and comparison of cartridge cases/shotshells

Range of conclusions for cartridge/cartridge case/shotshell comparisons

Documentation of examination results and comparisons

5.2.11 Shotshell Component Examinations

Shotshell components, when fired through the barrel of a shotgun, may acquire surface features 

from the internal surfaces of the barrel. Additionally, shotshell components may be examined for 

gauge determination, possible manufacture, shot size, and/or composition. Recommended articles 

and references for the below subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Gauge determination

Design and manufacture features 

Shot size and composition determination

Slug examination

Wad examination

5.2.12 Tool Manufacturing

Building upon manufacturing and machining knowledge, examiners must be familiar with the 

variety of methods used to create tools. Of specific importance are the techniques applied to tool 

working surfaces that may come into contact with evidentiary items. This understanding will assist 

the trainee in assigning significance to the toolmarks encountered during examinations, and will 

therefore assist with source conclusions. Recommended articles and references for the below 

subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Definition of tool, both common and in the context of toolmark examination
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Common types of hand tools, how they are used, and their associated parts.

Common manufacturing methods for hand tools

Screwdrivers

Bolt Cutters

Knives

Chisels

Hammers

Diagonal Pliers

Tongue and Groove Pliers

Shears/snips

The following subject areas should be included in a training program:

Tours of tool manufacturers

5.2.13 Toolmark Examinations

Knowledge of common tool actions and the wide variety of ways that tools can leave toolmarks is 

essential to the toolmark examiner. Additionally, examiners must be able to classify toolmarks, 

evaluate areas of possible subclass influence, and compare toolmarks for the purpose of rendering 

source conclusions. Recommended articles and references for the below subject areas can be 

located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Categories of tool actions:

Shearing action

Pinching action

Scraping action

Slicing action

Gripping action

Prying action

Crimping action

Class characteristic evaluation of toolmarks

Creating test marks in different substrates

Casting methods

Recognition of potential subclass characteristics

Evaluation and comparison of toolmarks

Range of conclusions for toolmark comparisons

Documentation of examination results and comparisons

5.2.14 Casework Documentation

Casework documentation is generated during the analysis of evidence. The purpose of this 

documentation is to support the conclusions that are reached. Casework shall be documented in 

such a way that, in the absence of the primary examiner, another qualified examiner could 

understand, evaluate, and interpret the work performed and the conclusions reached. 
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The following subject areas shall be included in a training program:

Types of information that must be recorded

Types of information that may be recorded

Acceptable forms of documentation

Quality system requirements for casework documentation

5.2.15 Casework Exercises

Casework exercises should be sufficient to impart to the trainee a full knowledge of a FSSP’s 

casework process.

The following subject areas shall be included in a training program:

Evidence assignment and chain of custody

Proper evidence handling procedures

Simulated casework

Supervised casework

Verification and review

5.2.16 Known Same Source/Known Different Source Exercises

Comparisons of KSSTs and KDSTs are a core component of training for firearm and toolmark 

examiners. KSST and KDST comparisons develop a trainee's ability to recognize levels of 

correspondence that are consistent with toolmarks known to have been created by the same tool or 

same surface of the tool, and levels of correspondence that are consistent with toolmarks known to 

have been created by different tools or different areas of the same tool.

For the purposes of this document, a single KSST or KDST comparison exercise consists of a 

complete comparison examination of two items (i.e. bullets, cartridge cases, etc.). 

Samples for use in KSST and KDST exercises are typically produced by trainers or trainees who are 

direct witnesses to their creation, thereby establishing ground truth.

The source of the toolmarks used to meet this requirement should reflect the categories of testing 

included in training. For example, if the training program is exclusively firearms examinations, most 

of these exercises should be conducted with bullets, cartridge cases, and shotshells. However, some 

exposure to sources of toolmarks outside of the trainee’s expected categories of testing may also be 

beneficial. This requirement may be met through the cumulative completion of various training 

exercises and supplemented as necessary to meet the minimum number. Regardless, training 

records shall clearly document the quantity of each type of comparison completed for this 

requirement.

The following studies shall be conducted and documented, regardless of which categories of testing 

the trainee will be qualified in. The numbers listed are a combined total, it is not necessary to 

repeat the exercise for non-firearm toolmarks:

200 Known Same Source Toolmark comparisons, including both impressed and striated toolmarks.
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200 Known Different Source Toolmark comparisons, including both impressed and striated 

toolmarks.1

Some of the KDST comparisons shall include samples created by consecutively manufactured 

tools/firearms.

In order to familiarize trainees with QCMS, the FSSP should consider documenting runs of 

consecutive matching striae for a portion or all of the above exercises. 

5.2.17 Communication, Legal Issues, Court

These topics address the intersection of science and the law, and the necessity of effective 

communication with various stakeholders in the legal system. Recommended articles and 

references for the below subject areas can be located in the AFTE Training Manual as well as the 

AFTE Admissibility Resource Kit located on the AFTE website.

The following topics shall be addressed in examiner training:

Courtroom procedures (local, state, federal)

Contemporary admissibility issues

Role of expert testimony

Public speaking

Communicating within the judicial system

Courtroom etiquette 

Discovery requirements

Moot court exercises

5.2.18 Ethics, Bias, Human Factors

Knowledge of common forms of bias is an essential part of any attempt to limit the influence of bias 

within a forensic science discipline. Likewise, a sound institutional knowledge of ethical issues 

related to forensic science helps build and maintain the integrity of the persons and institutions 

performing forensic analyses. 

The following topics shall be addressed in examiner training:

Contextual information

Confirmation, cognitive, explicit, and implicit bias

Task relevant information

Information is task-relevant if it is necessary for drawing conclusions:

about the propositions in question,

from the physical evidence that has been designated for examination,

1

The number 200 was chosen after a survey of five training manuals currently in use by federal and 

state/local FSSPs. Please note that the provision of a minimum number is intended to prevent insufficient 

exposure to KSST/KDSTs, and should not be construed as the “perfect” number of studies to be qualified as a 

toolmark examiner. The five agencies surveyed were the Bureau of Alcohol, Tobacco, Firearms and 

Explosives, the Federal Bureau of Investigation, the Illinois State Police, the Indiana State Police, and the Los 

Angeles Police Department.
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Toolmark Examiner Training Program

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through the correct application of an accepted analytic method by a qualified 

analyst. 

Neutrality in forensic science

Codes of ethics

5.2.19 Forensic Science Service Provider Operations

In the absence of other institutional or FSSP-wide training requirements for examiners in all 

disciplines, the following topics shall be included in examiner training:

Authority structure within the FSSP

Quality system

Accreditation matters

Laboratory safety

Safe handling of evidence / universal precautions

Evidence tracking / laboratory information managements systems (LIMS)

6 Optional Topics

6.1 Distance Determination via Gunshot Residues

In this section, “distance determination” refers to any determinations that can be made regarding 

the distance from the muzzle of the firearm to an impact surface based upon the examination of 

gunshot residues present on impact surface(s). Recommended articles and references for the below 

subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Factors regarding the deposition of residue from the use of a firearm

Ammunition type

Firearm type

Revolvers

Pistols

Rifles

Shotguns

Substrate type

Visual inspection

Hole

Ripping/tearing

Singeing/burning/melting

Presence of powder/particulate or vaporous lead

Chemistry and examination techniques for:

Nitrites

Lead

Copper

Application of techniques for nitrites and lead

Test known distance patterns using appropriate techniques

Test unknown distance patterns using appropriate techniques
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Recommendations for a Firearm and

Toolmark Examiner Training Program

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Comparison of known and unknown patterns, documentation, interpretation and conclusions, 

including limitations.

Measurement of Uncertainty

6.2 Distance Determination via Shot Patterns

In this section, “distance determination” refers to any determinations that can be made regarding 

the distance from the muzzle of the firearm to the impact surface based upon the examination of 

impact patterns present on impact surface(s). Recommended articles and references for the below 

subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Factors regarding shot patterns from the use of a firearm

Ammunition types

Pellet sizes

Shotshell wadding

Buffer Material

Firearm type

Shotgun choke systems

Measuring shot patterns

Correcting for non-orthogonal patterns

Creating and measuring shot patterns at known distances

Comparison of known and unknown patterns, interpretation and conclusions, including 

limitations

Measurement of Uncertainty

6.3 Serial Number / Obliterated Character Restoration

The recovery of an obliterated serial number on a firearm or characters present on other evidence 

types can be a valuable piece of intelligence for investigators. This section is designed to impart 

knowledge about common destruction processes and both knowledge of and experience using the 

many recovery methods available to examiners. Recommended articles and references for the 

below subject areas can be located in the AFTE Training Manual. 

The following subject areas shall be included in a training program:

Serial number application processes

Types of destruction methods

Grinding

Over stamping

Peening

Gouging

Heating

Welding

Scratching

Drilling

Terminology regarding serial number recovery processes
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Recommendations for a Firearm and

Toolmark Examiner Training Program

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Chemical methods

Polishing methods

Sanding methods

Electro-chemical methods

Magnetic Particle inspection

Barcode decryption

Lighting techniques

Use of different recovery processes

Application of recovery methods to ferrous firearms

Application of recovery methods to non-ferrous firearms

Application of recovery methods by barcode decryption

Documentation of recovery of serial numbers

Photography

Casting prior to recovery if toolmarks are present

Note taking

Reporting Conclusions

Alternative sources of serial number recovery

Secondary serial numbers

Secondary/hidden manufacturer codes

6.4 Fracture Examinations

The analysis of fractured objects and surfaces to determine if they were once part of the same 

object is performed by firearm and toolmark examiners in some FSSPs. The list of training topics 

below is designed only to be used in combination with either firearm examiner or toolmark 

examiner training, and does not provide sufficient training and skill if it is completed without 

firearm or toolmark training. Additionally, since this document pertains to firearm and toolmark 

training, the listed training requirements are for that purpose only; this document imposes no 

requirements or recommendations on persons training in fracture examinations within other 

disciplines. Recommended articles and references for the below subject areas can be located in the 

AFTE Training Manual. 

The following topics shall be addressed in examiner training:

Failure modes of brittle materials

Plastic deformation

Elastic deformation

Class characteristics

Physical fit

Reverse lighting techniques, microscopic comparison

Casting or coatings for translucent/transparent materials

Range of conclusions

KSST and KDST studies shall be performed utilizing a variety of substrate materials and object 

geometries that are typical of casework.
OSAC 2021-N-0012 Requirements and 

Recommendations for a Firearm and

Toolmark Examiner Training Program

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Bibliography

Association of Firearm & Tool Mark Examiners (AFTE) Training Manual, March 3rd, 2001 - current, 

https://AFTE.org

Standard Practice for Forensic Science Practitioner Training, Continuing Education, and 

Professional Development, E2917, ASTM International, 2019

ASTM Standard E2917-19a, “Standard Practice for Forensic Science Practitioner Training 

Continuing Education, and Professional Development Programs,” ASTM International, West 

Conshoshocken, PA, 2019, DOI: 10.1520/E2917-19a, www.astm.org.