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

2

Draft 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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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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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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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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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

Incomplete	firearms	(“80%”	firearms,	receiver	blanks,	home-built)
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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.	

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

Firing	pin	impression

Breech	face	marks
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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

Common	types	of	hand	tools,	how	they	are	used,	and	their	associated	parts.
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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.	

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