U.S. flag

An official website of the United States government, Department of Justice.

Firearms Examiner Training

Module 07: Equipment and Instrumentation

Home  |  Glossary  |  Resources  |  Help  |  Contact Us  |  Course Map

illustration of a gun being fired with text that says Equipment and Instrumentation
National Institute of Justice (NIJ) (see reuse policy).


Author: John H. Dillon, Jr.
Headshot of Author John H. Dillon, Jr
National Institute of Justice (NIJ) (see reuse policy).
John Dillon earned a Bachelors degree from the United States Naval Academy and an M.Ed. from the University of Virginia. Commissioned in the United States Marine Corps in 1964, he attained the rank of Captain of Marines. Appointed an FBI special agent in 1970, Mr. Dillon investigated diverse criminal violations, including organized crime, bank robberies, extortions, and kidnappings. In 1976, he received orders to the firearms/toolmarks unit of the FBI Laboratory for training as an examiner, where he evaluated evidence and provided on-site field support in domestic and international cases. He also designed and taught basic and management-level forensic courses at the FBI Academy, Quantico, Virginia (1982-1988). In 1994, Mr. Dillon retired from the FBI as chief of the firearms/toolmarks unit. He currently provides consultant services in forensic firearms cases and develops and delivers firearms training.



This module describes items common to all forensic scientists, and items unique to the firearm/toolmark examiner. The critical tools necessary for firearm/toolmark identification include the comparison microscope, appropriate facilities, specialized tools, equipment, instruments, and supplies.

Each laboratory will also have a unique configuration of computer systems and software for technical and administrative purposes. Students should take the initiative to learn the systems that are new to them.


At the conclusion of this module the student should be able to do the following:

  • Explain the following and their relationships:
    • Standards
    • Accuracy
    • NIST traceability
    • Measurements
    • Laboratory accreditation
    • Laboratory protocols
  • Define when an examiner would use the following reference resources:
    • The web site of the Association of Firearm and Toolmark Examiners (AFTE)
    • The web site of the Scientific Working Group for Firearms and Toolmarks (SWGGUN)
  • Define the measurement equipment for weight and force, specifically:
    • Digital scales
    • Trigger pull weights
  • Describe the types of equipment available to firearm/toolmark examiners for measuring dimensions, such as these:
    • Glass reticules in the eyepieces of stereo microscopes
    • Older comparison microscopes using glass reticules
    • Filar micrometer eyepieces
    • Electronic reticules used with stereo microscopes
    • Digital measuring equipment
    • Digital micrometers
    • Digital calipers
    • Steel machinists scale
  • Articulate the use of a chronograph
  • Describe the use of the stereo and the comparison microscopes
  • Describe the examiners use of tools and supplies at the laboratory bench
  • Define the occasion for the examiners requirements for the following firing facilities:
    • Indoor range
    • Bullet recovery system
    • Outdoor range
  • Describe the available imaging systems of use to the examiner, including these:
    • Film imaging
    • Digital imaging
  • Describe the types of equipment normally required for laboratory field support in crime scenes
  • Describe the current capabilities of the following systems:
    • Integrated Ballistics Identification System (IBIS)
    • MatchPoint Plus
    • BulletTRAX-3D System
  • Describe the firing facilities and bullet recovery systems used by examiners

AFTE Knowledge and Ability Factors

K 20. Knowledge of various photographic techniques and their application for documenting evidence and analytical results, and for preparing courtroom exhibits
K 24. Knowledge of quality assurances and quality control procedures and how they are maintained by firearm and toolmark examiners
K 29. Knowledge of various microscopy equipment; such as stereo binocular, comparison, video microscope, compound, refer to specialist: (including polarizing), scanning electron microscope
K 32. Knowledge of photomicrography equipment and its components (such as digital photography, video cameras, camera-to-microscope adapters), determination of effective magnification on printed photographs, Out of date: determination of proper exposure times
K 33. Knowledge of when and how to properly use measuring equipment (filar micrometer eyepieces, stage micrometers, dial micrometers and calipers, vernier micrometers and calipers, gauges and balances, rulers, tape measures. Shooting Reconstruction: levels, angle finders, protractors, etc.)
K 38. Knowledge of how and when to use various vises, clamps, and restraining devices
K 39. Knowledge of how and when to use gunsmithing tools
K 40. How and when to use ultrasonic baths and cleaners
K 43. Knowledge of how and when to use borescopes
K 44. Knowledge of how and when to use borelights
K 46. How and when to use different probes (such as wood, fiberglass, metal, etc.) for bullet holes
K 57. Knowledge of how and when to use various small handtools (such as screwdrivers, hammers, pliers, etc.)
K 59. Knowledge of how and when to use fume hoods
K 65. How and when to use chronograph equipment
K 67. Knowledge of how and when to use examination tables. (laboratory bench)
K 68. Knowledge of how and when to use bullet and cartridge recovery systems (water, snail, cotton waste, etc.)
K 69. Knowledge of how and when to use bullet pullers
K 70. Knowledge of how and when to use spring trigger pull scales
K 71. Knowledge of how and when to use trigger pull weights
K 144. Knowledge of where to find and how to use various reference collections, tables, and databases (including ballistic tables, IBIS , firearm reference collections, ammunition reference collections, general rifling characteristics file for make and model determinations, etc.), and the limitations of such databases and tables
K 105. Knowledge of bullet recovery methods, and the advantages and disadvantages of each
A 14. Ability to perform routine maintenance on laboratory equipment and machines (includes calibrating instruments per laboratory protocol, as appropriate)
A 16. Ability to operate job-related computer systems
A 18. Ability to operate basic laboratory equipment
A 19. Ability to understand and interpret technical data output from laboratory instruments

Back Forward