Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 1 

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Requirements and 

Recommendations for a 

Firearm and Toolmark 

Examiner Training 

Program 

Firearms & Toolmarks Subcommittee 

Physics/Pattern Interpretation Scientific Area Committee

12 Organization of Scientific Area Committees (OSAC) for Forensic Science

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Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 2 

Draft OSAC Proposed Standard

OSAC 2021-N-0012

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25 Requirements and Recommendations 

26 for a Firearm and Toolmark Examiner 

27 Training Program 

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31 

Prepared by 

Firearms & Toolmarks Subcommittee 

Version: 1.0 

32 January 2021 

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36 Disclaimer: 

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Disclaimer: This OSAC Proposed Standard was written by the Firearms & Toolmarks 

Subcommittee of 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 forensic-science 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.
Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 3 

56 Keywords: Firearm and Toolmark Examination, Firearm and Toolmark Examiner, Training

57 

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

59 toolmark examiner training programs. 

60 

61 

62 Foreword

63 

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

65 toolmark examiner. 

66 

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

68 Scientific Area Committees (OSAC). 

69 
Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 4 

70 Acknowledgements 

71 

72 Editor: 

73 

74 Deputy Editor(s): 

75 

76 Drafting Working Group Members: 

77 

78 Jason Crafton Missouri State Highway Patrol 

79 William E. Demuth II Illinois State Police 

80 Jodi Marsanopoli Bureau of Alcohol, Tobacco, Firearms and Explosives 

81 Doug Murphy Federal Bureau of Investigation 

82 Melissa Oberg Indiana State Police 

83 Jacob Seror Los Angeles Police Department 

84 

85 

86 

87 Consensus Group Members: 

88 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 5 

89 Table of Contents 

90 

91 1 Scope 6 

92 2 Normative References 6 

93 3 Terms and Definitions 6 

94 4 Requirements 7 

95 5 Optional Topics 19 

96 

97 

98 Annex A (informative) Bibliography 

99 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 6 

100 1 Scope 

101 

102 This standard covers minimum requirements and recommendations for firearm and toolmark 

103 examiner training programs. The requirements listed in this standard include the essential skills 

104 and knowledge needed to perform successfully in the discipline. The additional recommended 

105 elements are considered by the subcommittee to be highly beneficial and worthy of inclusion 

106 should the necessary resources be available. Requirements and recommendations include training 

107 topics, documentation, casework exercises, and methods for testing competency. This document 

108 will also provide guidance regarding which training elements may be removed in cases where a 

109 trainee is being qualified in only one category of testing. This standard does not preclude agencies 

110 from adding additional mission-specific requirements. 

111 

112 2 Normative References 

113 

114 none 

115 

116 3 Terms and Definitions 

117 

118 3.1 Firearm and Toolmark Examination 

119 A discipline of forensic science that includes the classification and comparison of microscopic 

120 toolmarks created by firearms or other tools. It may also include the examination of firearms and 

121 non-firearm tools, serial number restoration, and muzzle-to-object distance determinations. 

122 

123 3.2 Firearm Examination

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

125 comparison of microscopic toolmarks created by firearms on ammunition components. It may also 

126 include the examination of firearms, serial number restoration, and muzzle-to-object distance 

127 determinations.

128 

129 3.3 Firearm and Toolmark Examiner 

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

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

132 forensic science service provider. 

133 

134 3.4 Firearm Examiner 

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

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

137 provider. 

138 

139 3.5 Forensic Science Services Provider (FSSP) 

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

141 

142 3.6 Known Match 

143 Toolmarks known to have been made by the same tool. 

144 

145 3.7 Known Non-Match 

146 Toolmarks known to have been made by different tools or different working surfaces of the same 

147 tool. 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 7 

148 

149 3.8 Toolmark Examiner 

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

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

152 service provider. 

153 

154 3.9 Toolmark Examination 

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

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

157 examination of non-firearm tools. 

158 

159 3.10 Trainee 

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

161 toolmark examination. 

162 

163 3.11 Trainer 

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

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

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

167 provider to perform training-related duties. 

168 

169 4 Requirements

170 

171 4.1 Administrative

172 

173 4.1.1 Documentation 

174 

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

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

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

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

179 of training shall be documented and retained. 

180 

181 4.1.2 Required Elements 

182 

183 All trainees shall complete sections 4.1 (all), 4.2.1, 4.2.3, 4.2.4, 4.2.8, 4.2.13 - 4.2.17 

184 Trainees being trained in firearms, but not toolmarks, shall also complete sections 4.2.2, 4.2.5, 4.2.6, 

185 4.2.7, 4.2.9, 4.2.10 

186 Trainees being trained in toolmarks, but not firearms, shall also complete sections 4.2.11 and 

187 4.2.12. 

188 Trainees being trained in both firearms and toolmarks shall also complete sections 4.2.2, 4.2.5, 

189 4.2.6, 4.2.7, 4.2.9, 4.2.10, 4.2.11 and 4.2.12. 

190 The requirements for total known match and known non-match comparisons shall not be reduced 

191 based upon categories of training. 

192 

193 Trainees being trained in fracture match comparisons (5.4), serial number restoration (5.3), or 

194 distance determinations (5.1, 5.2) shall also complete the corresponding requirements for those 

195 categories. 

196 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 8 

197 4.1.3 Training Topics Not Present 

198 

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

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

201 training topics that are relevant and beneficial. 

202 

203 4.1.4 Training Methods 

204 

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

206 responsibility of each FSSP to determine the most effective methods for training. A successful 

207 training program includes reading, lecture, group discussions, real or mock examinations under the 

208 guidance of a qualified examiner, and a substantial amount of “hands-on” self-study of 

209 firearms/tools, toolmarks, and comparison techniques. The order of the topics listed in this 

210 document is not intended to be the recommended order of training. Many of the topics are 

211 interrelated and do not necessarily need to be taught separately. 

212 

213 4.1.5 Testing 

214 

215 Competency in the various training topics may be assessed using a combination of: written tests, 

216 oral examinations, intercomparison tests, and mock casework. 

217 

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

219 comparison examinations, and written reports. 

220 

221 Training shall include mock courtroom exercise(s). 

222 

223 4.1.6 Supervised Casework 

224 

225 Trainees shall have their initial casework reviewed or supervised. This process shall occur in the 

226 latter stages of training, or immediately upon completion of training. FSSBs shall clearly define both 

227 the process and the extent to which it will occur, such as a particular number of cases or a certain 

228 number of months. 

229 

230 4.1.7 Evaluation of Training Program 

231 

232 The forensic science service provider shall establish a formal mechanism for trainees to provide 

233 feedback on the effectiveness of the training program. This information shall be used by the FSSP to 

234 evaluate, update and improve the training program on a periodic basis. 

235 

236 4.1.8 Continuing Education 

237 

238 After completion of training, examiners shall engage in continuing education, such as attending 

239 conferences, participating in research, or visiting manufacturing facilities. FSSPs shall dedicate the 

240 necessary resources to ensure compliance and define minimum continuing education requirements 

241 for qualified examiners. 

242 

243 4.2 Training Topics 

244 

245 4.2.1 General Manufacturing and Machining 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 9 

246 

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

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

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

250 comparison examinations, and when rendering source conclusions. 

251 

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

253 

254 Gross Forming Techniques 

255 Forging 

256 Hand 

257 Drop 

258 Press 

259 Casting 

260 Sand 

261 Investment/Lost Wax 

262 Fine Forming Techniques 

263 Turning 

264 Milling 

265 Drilling 

266 Boring 

267 Reaming 

268 Broaching 

269 Sawing 

270 Electrical discharge machining 

271 Electrochemical machining 

272 Metal injection molding 

273 Finishing Techniques 

274 Grinding/Sanding 

275 Etching 

276 Media blasting 

277 Tumbling media 

278 Finishes 

279 Bluing 

280 Browning 

281 Oxide (Parkerizing, etc.) 

282 Plating 

283 Coatings/Paint 

284 Key Machining Concepts for Toolmark Identification 

285 Chip formation 

286 Plastic deformation 

287 Tool wear 

288 Built Up edge 

289 

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

291 

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

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

294 methods listed above 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 10 

295 

296 General concepts and practices of Additive Manufacturing (3-D printing) 

297 

298 4.2.2 Firearms Manufacturing 

299 

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

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

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

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

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

305 nature of toolmarks present on fired and unfired ammunition components. 

306 

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

308 

309 Barrels 

310 Blanks 

311 Deep hole drilling 

312 Reaming 

313 Extrusion (Hi-Point) 

314 Rifling 

315 Button 

316 ECM (Electrochemical Machining) 

317 EDM (Electrical Discharge Machining) 

318 Gang Broach 

319 Hammer Forged 

320 Single Point/Hook/Scrape Rifling 

321 Finishing 

322 Straightening 

323 Chambering 

324 Throating 

325 Crowning 

326 Contouring 

327 Honing/Lapping/Polishing 

328 

329 Common machining techniques that are used to produce the following parts: 

330 Breech faces 

331 Chambers 

332 Hammers/Firing pins/Strikers 

333 Firing pin aperture 

334 Extractors 

335 Ejectors 

336 Feed ramps / forcing cones 

337 Magazines 

338 Ejection port 

339 

340 Common alterations and associated toolmarks 

341 Sawed off barrel 

342 Muzzle attachments 

343 Front sight alteration 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 11 

344 

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

346 

347 Additive Manufacturing (3-D printing) 

348 

349 Tours 

350 Firearm Manufacturers 

351 Barrel Manufacturers

352 

353 4.2.3 History of Firearm and Toolmark Examinations 

354 

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

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

357 laws prohibiting the use of certain firearms and accessories. 

358 

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

360 

361 Evolution of use in court 

362 Evolution of examination and comparison techniques 

363 Photomicrographs 

364 Comparison microscope 

365 

366 Literature Review 

367 Relevant peer reviewed journal articles and textbooks 

368 

369 4.2.4 Theory and Validity of Firearm and Toolmark Examinations 

370 

371 The successful application of examination techniques and any subsequent communication 

372 regarding the results of examinations requires a complete understanding of the scientific 

373 foundation of firearm and toolmark examinations. Theory, nomenclature, research, and statistical 

374 methods are all crucial to successful completion of training. 

375 

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

377 

378 AFTE Theory of Identification 

379 Class characteristics 

380 Subclass characteristics 

381 Individual characteristics 

382 Types of Toolmarks 

383 Impressed Toolmarks 

384 Striated Toolmarks 

385 Concept of Known Match and Known Non-Match comparisons 

386 Research 

387 Validity Testing 

388 Early studies 

389 Black, White, and Grey box studies 

390 Error Rates 

391 Expressions of Confidence 

392 Criticisms of Current Methods 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 12 

393 Basic concepts of QCMS 

394 

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

396 

397 Statistics, including Likelihood Ratios 

398 Toolmark topography instruments and correlation algorithms 

399 

400 4.2.5 Ammunition 

401 

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

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

404 with ammunition. 

405 

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

407 Ammunition manufacturing 

408 Blanking 

409 Cupping 

410 Drawing 

411 Swaging 

412 Headstamps 

413 Case/primer materials 

414 Assembly 

415 Crimping 

416 Reloading 

417 

418 Terminology associated with both historic and modern ammunition 

419 Caliber naming conventions 

420 Cartridge case design 

421 

422 Terminology associated with shotshell ammunition 

423 Components 

424 Gauge 

425 Pellet sizes 

426 

427 Caliber determination of bullets 

428 Instrumentation used 

429 

430 Caliber determination of cartridges/cartridge cases 

431 Headstamps 

432 Case dimensions 

433 Caliber families 

434 Mismatching and Interchangeability of ammunition and firearm caliber 

435 Wildcat cartridges 

436 

437 Evolution of ammunition 

438 Propellants, black powder to modern smokeless powder 

439 Rimmed and centerfire 

440 Types of primers 

441 Bullet shapes, designs 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 13 

442 Current common brands and types of ammunition 

443 

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

445 

446 Tours of ammunition factories 

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

448 interpretation limitations 

449 

450 4.2.6 Firearm Design and Terminology 

451 

452 The successful examination of firearms requires comprehensive knowledge of terminology, 

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

454 

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

456 

457 Evolution of Firearms 

458 Ignition Systems 

459 Safeties 

460 Firearms Terminology 

461 Pistol 

462 Revolver 

463 Rifle 

464 Shotgun 

465 Parts and nomenclature associated with types of firearms 

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

467 videos 

468 Cycle of fire 

469 Action types 

470 Bolt action 

471 Lever action

472 Pump action 

473 Revolver 

474 Semi-Automatic/Automatic Actions 

475 Blowback 

476 Recoil 

477 Gas operated 

478 Modes of Fire 

479 Single Action 

480 Double Action 

481 Burst/Fully Automatic 

482 Post manufacture alterations and accessories 

483 Full Auto conversions 

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

485 Drop-in barrels 

486 Bump stocks 

487 Trigger modifications 

488 

489 

490 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 14 

491 4.2.7 Examination of Firearms 

492 

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

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

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

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

497 

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

499 

500 Safe handling and firing of firearms 

501 Function Exams 

502 Firearm safety/recall list 

503 Test firing and selection of appropriate ammunition

504 Safety tests 

505 Trigger Pull 

506 Barrel and overall length measurements

507 Impact test

508 Casting of firearm parts/alternate tools for creating test marks 

509 

510 Firearms Laws 

511 NFA (National Firearms Act) 

512 GCA (Gun Control Act) 

513 Relevant State/Local Specific Laws 

514 

515 Firearm components that potentially create toolmarks: 

516 

517 Lands and grooves 

518 Breech / bolt face 

519 Firing pin 

520 Ejector 

521 Ejection port 

522 Extractor 

523 Chamber 

524 Feed ramp 

525 Magazine 

526 

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

528 

529 4.2.8 Microscope Use and Familiarization 

530 

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

532 examinations of fired ammunition components and toolmarked surfaces. 

533 

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

535 

536 Design and use of a stereoscope 

537 Design and use of a comparison microscope 

538 Light sources and lighting techniques 

539 Photographic techniques 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 15 

540 Comparison techniques 

541 

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

543 

544 Focus variation microscopy 

545 Interferometric microscopy 

546 Confocal microscopy 

547 Photometric microscopy 

548 Virtual comparison microscopy 

549 

550 4.2.9 Bullet Examinations 

551 

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

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

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

555 certain classes of firearms from any association with the fired bullet.

556 

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

558 

559 Caliber determination 

560 Design features 

561 Direction of twist 

562 Land and groove impression measurement techniques 

563 General Rifling Characteristics (GRC) database 

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

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

566 Evaluation and comparison of questioned bullets 

567 Range of conclusions for bullet comparisons 

568 Documentation of exam results and comparisons 

569 

570 4.2.10 Cartridge/Cartridge Case/Shotshell Examinations 

571 

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

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

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

575 firearms from any association with the ammunition component.

576 

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

578 

579 Recognition of marks on cartridges/cartridge cases/shotshells 

580 Firing pin impression 

581 Breech face marks 

582 Aperture impression/shear 

583 Extractor 

584 Ejector 

585 Firing pin drag 

586 Chamber marks 

587 Magazine lip marks 

588 Loaded chamber indicator impressions 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 16 

589 Shell stop marks 

590 Anvil Marks 

591 Caliber/gauge determination 

592 Design features 

593 Recognition of potential subclass marks on fired cartridge cases/shotshells 

594 Recognition of manufacturing marks 

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

596 ammunition 

597 Evaluation and comparison of cartridge cases/shotshells 

598 Range of conclusions for cartridge/cartridge case/shotshell comparisons 

599 Documentation of exam results and comparisons 

600 

601 4.2.11 Tool Manufacturing 

602 

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

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

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

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

607 therefore assist with source conclusions. 

608 

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

610 

611 Definition of tool, both common and in the context of toolmark examination 

612 Common types of hand tools and their associated parts. 

613 

614 Common manufacturing methods for hand tools 

615 Screwdrivers 

616 Bolt Cutters 

617 Knives 

618 Chisels 

619 Hammers 

620 Diagonal Pliers 

621 Tongue and Groove Pliers 

622 Shears/snips 

623 

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

625 

626 Tours of tool manufacturers 

627 

628 4.2.12 Toolmark Examinations 

629 

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

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

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

633 rendering source conclusions.

634 

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

636 

637 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 17 

638 Categories of tool actions: 

639 Shearing action 

640 Pinching action 

641 Scraping action 

642 Slicing action 

643 Gripping action 

644 Prying action 

645 Crimping action 

646 Class characteristic evaluation of toolmarks 

647 Creating test marks in different substrates 

648 Casting methods 

649 Recognition of potential subclass characteristics 

650 Evaluation and comparison of toolmarks 

651 Range of conclusions for toolmark comparisons 

652 Documentation of exam results and comparisons 

653 

654 4.2.13 Casework Documentation 

655 

656 Casework documentation must satisfy various stakeholders, to include the examiner, technical and 

657 administrative reviewers, FSSP quality guidelines, investigators, and any interested parties at trial. 

658 

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

660 

661 Types of information that must be recorded 

662 Types of information that may be recorded 

663 Acceptable forms of documentation 

664 Quality system requirements for casework documentation 

665 

666 4.2.14 Casework Exercises 

667 

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

669 casework process. 

670 

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

672 

673 Evidence assignment and chain of custody 

674 Proper evidence handling procedures 

675 Simulated casework 

676 Supervised casework 

677 Verification and review 

678 

679 4.2.15 Known Non-Match (KNM)/Known Match (KM) Exercises 

680 

681 Comparisons of KMs and KNMs are a core component of training for firearm and toolmark 

682 examiners. KM and KNM comparisons develop a trainee's ability to recognize levels of 

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

684 and levels of correspondence that are consistent with toolmarks known to have been created by 

685 different tools. 

686 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 18 

687 For the purposes of this document, a single KM or KNM comparison examination consists of a 

688 complete comparison examination of two items (bullets, cartridge cases, etc.), not a comparison of 

689 only two land impressions or two firing pin impressions. 

690 

691 Samples for use in KM and KNM exercises are typically produced by trainers or trainees who are 

692 direct witnesses to their creation, thereby establishing ground truth. 

693 

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

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

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

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

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

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

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

701 requirement. 

702 

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

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

705 repeat the exercise for non-firearm toolmarks: 

706 

707 200 Known Non-Match comparisons, including both impressed and striated toolmarks. 

708 

200 Known Match comparisons, including both impressed and striated toolmarks. 709 1

710 

711 Some of the KNM comparisons shall include samples created by consecutively manufactured 

712 tools/firearms. 

713 

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

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

716 

717 4.2.16 Communication, Legal Issues, Court 

718 

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

720 communication with various stakeholders in the legal system. 

721 

722 The following topics shall be addressed in examiner training: 

723 

724 Courtroom procedures 

725 Court admissibility 

726 Role of expert testimony 

727 Public speaking 

728 Communicating within the judicial system 

729 Courtroom etiquette 

 

1

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

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

exposure to KM/KNMs, 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. 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 19 

730 Court rulings, including the range of conclusions permitted 

731 Discovery requirements 

732 Moot court exercises 

733 

734 4.2.17 Ethics, Bias, Human Factors 

735 

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

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

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

739 performing forensic analyses. 

740 

741 The following topics shall be addressed in examiner training: 

742 

743 Contextual information 

744 Confirmation bias 

745 Task relevant information 

746 Neutrality in forensic science 

747 Codes of ethics 

748 

749 4.2.18 Forensic Science Service Provider Operations 

750 

751 In the absence of other institutional or forensic science service provider-wide training 

752 requirements for examiners in all disciplines, the following topics shall be included in examiner 

753 training: 

754 

755 Authority structure within the FSSP 

756 Quality system 

757 Accreditation matters 

758 Laboratory safety 

759 Safe handling of evidence / universal precautions 

760 Evidence tracking / LIMs systems 

761 

762 5 Optional Topics 

763 

764 5.1 Distance Determination via Gunshot Residues 

765 

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

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

768 gunshot residues on clothing or other impact sites. 

769 

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

771 

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

773 Ammunition type 

774 Firearm type 

775 Revolvers 

776 Pistols 

777 Rifles 

778 Shotguns 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 20 

779 Substrate type 

780 Visual inspection 

781 Hole 

782 Ripping/tearing 

783 Singeing/burning/melting 

784 Presence of powder/particulate or vaporous lead 

785 Chemistry and examination techniques for 

786 Nitrites 

787 Lead 

788 Copper 

789 Application of techniques for nitrites and lead 

790 Test known distance patterns using appropriate techniques 

791 Test unknown distance patterns using appropriate techniques 

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

793 including limitations 

794 

795 5.2 Distance Determination via Shot Patterns 

796 

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

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

799 impact patterns on a victim’s clothing or other impact sites. 

800 

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

802 

803 Factors regarding shot patterns from the use of a firearm

804 Ammunition types 

805 Pellet sizes 

806 Shotshell wadding 

807 Buffer Material 

808 Firearm type 

809 Shotgun choke systems 

810 Measuring shot patterns 

811 Correcting for non-orthogonal patterns 

812 Creating and measuring shot patterns at known distances 

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

814 limitations

815 

816 5.3 Serial Number / Obliterated Character Restoration 

817 

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

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

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

821 many recovery methods available to examiners. 

822 

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

824 

825 Serial number application processes 

826 Types of destruction methods 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 21 

827 Grinding 

828 Over stamping 

829 Peening 

830 Gouging 

831 Heating 

832 Welding 

833 Scratching 

834 Drilling 

835 Terminology regarding serial number recovery processes 

836 Chemical methods 

837 Polishing methods 

838 Sanding methods 

839 Electro-chemical methods 

840 Magnetic Particle inspection 

841 Barcode decryption 

842 Lighting techniques 

843 

844 Use of different recovery processes 

845 Application of recovery methods to ferrous firearms 

846 Application of recovery methods to non-ferrous firearms 

847 Application of recovery methods by barcode decryption 

848 Documentation of recovery of serial numbers 

849 Photography 

850 Note taking 

851 Reporting Conclusions 

852 Alternative sources of serial number recovery 

853 Secondary serial numbers 

854 Secondary/hidden manufacturer codes 

855 

856 5.4 Fracture Examinations 

857 

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

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

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

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

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

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

864 requirements or recommendations on persons training in fracture examinations within other 

865 disciplines. 

866 

867 The following topics shall be addressed in examiner training: 

868 

869 Failure modes of brittle materials 

870 Plastic deformation 

871 Elastic deformation 

872 Class characteristics 

873 Physical fit 

874 Reverse lighting techniques, microscopic comparison 

875 Casting or coatings for translucent/transparent materials 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 22 

876 Range of conclusions 

877 

878 Known Match and Known Non-Match studies shall be performed utilizing a variety of substrate 

879 materials and object geometries that are typical of casework. 

880 
 Requirements and Recommendations for a 

Firearm and Toolmark Examiner Training Program 

DRAFT 23 

881 

882 Bibliography

883 

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

885 

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

887 Development, E2917, ASTM International, 2019