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ATF National Laboratories


ATF Laboratory Examinations

  • firearms
  • bullets, cartridges, shotshells
  • toolmarks
  • serial number/obliterated marking restoration
  • gunpowder and gunshot residue patterns
  • shooting reconstruction
  • firearms identification
  • the determination of whether a particular ammunition component was or was not fired from a specific firearm to the exclusion of all others
  • ammunition component = bullet, cartridge case, shotshell, shot, wadding

Examination of Firearms

  • routine examinations
  • all firearms are tested to see if they function as designed and are safe to operate
  • manufacturer, type, model and caliber information is recorded
  • the firearm is test fired
  • any firearm which is found to be "altered" during the routine examination is sent directly to FTB for determination
  • examination of ammunition components

Examination of Bullets

  • routine examination
    • determine manufacturer, caliber and type
    • determine make of firearm which may have fired bullet
  • bullet & firearm
    • bullet undergoes routine examination & is compared to test fire from firearm

Examination of Cartridge Cases

  • routine examination
    • determine manufacturer, caliber or gauge
    • determine make of firearm which may have fired cartridge
  • cartridge case & firearm
    • cartridge case undergoes routine examination
    • cartridge case is compared to test fire from firearm
  • live cartridges
    • determine if bullet has been loaded, extracted and/or ejected from a firearm & type of gun it may have been worked through.

Examination of Shot

  • determine size only
  • it is impossible to identify shot to a particular shotgun

Examination of Slug

  • determine size and gauge
  • some slugs can be identified to a particular shotgun

Examination of Wadding

  • determine gauge and manufacturer of shotshell
  • some waddings can be identified to a particular shotgun

Examination of Casing

  • determine gauge, manufacturer of shotshell
  • possibly determine make of shotgun which fired the casing

Packaging & Shipping


  • shipping boxes are available from:
    ATF Distribution Center
    P.O. Box 5950
    Springfield, VA 22150-5950
    (703)455-7801 (to place an order)
  • Box Size
    item # size of box (inches)
    m 3000.11 36 x 10 x 10
    m 3000.12 20 x 16 x 8
    m 3000.13 16 x 8 x 41/2
    m 3000.14 36 x 9 x 51/2
  • If fingerprint exams are requested, use plastic ties to secured gun to box.
  • Ship in "safe" condition
    • unloaded
    • breech open
    • safety strap through the barrel, chamber or breech
  • Ship via Federal Express
  • Every attempt should be made to unload guns. If a gun that is loaded must be shipped, notify the lab, document this in your transmittal letter and properly mark the shipping box.


  • Do not attempt to mark the bullet in any way
  • Ship via Federal Express
  • Never ship live ammunition through the U.S. Mail!
  • Revolvers: package rounds separately and note where each one was positioned in cylinder (especially important for round in hammer position)
  • Fired Components
    • package individually to protect markings
    • Ship via Federal Express

Examination of Tools

  • Defintion: the examination of transfer marks created by a hard object (tool) against a softer object and the comparison of these marks to tools which may have created these markings.
  • Routine examinations
    • type and/or design of tool used to create impression
    • size and/or specifications of tool used to create impression
    • any unusual features of the tool
    • type of action the tool employed
    • value of the toolmark for comparison purposes
  • Toolmark and suspect tool
    • determine if suspect tool is of the same class of tool which made toolmark
    • microscopic comparison of toolmark with a "test mark" made by suspect tool
  • Fracture matches
    • determination of whether two items were once a single unit
  • Pressure/Contact
    • determination of whether two objects were ever in contact with each other
  • Lock and key
    • examination to determine if a key fits a particular lock
    • examination of a lock to determine whether it is in a locked or unlocked mode
    • determination of whether an attempt was made to open a particular lock with an improper implement

Packaging & Shipping of Toolmark Evidence

  • All toolmark evidence and suspect tools should be individually packaged in sealable containers (paper bags, ziplock bags).
  • Do not make any test marks in the field, submit the actual suspect tool.
  • Label all toolmarks which should not be examined (ex: tools used or wires cut used by agent, bomb tech, etc.)
  • serial number/obliterated marking restoration
  • the application of magnetic, chemical, electrolytic and/or thermal techniques to a metallic object in order to reveal an obliterated mark.
  • all fully recovered serial numbers will be reported and should be searched by the agent through: The National Crime Information Center -and- the Treasury Enforcement Communications System

Shooting Reconstruction

  • Upon request, the Firearm Unit will respond to scenes and:
  • Determine shooting position(s)
    Determine the trajectory angle(s) of any fired projectiles
  • These findings along with the analysis of photographs, and evaluation of victim/witness statements, will assist the agent in developing possible scenarios/sequences of events at a crime scene involving a discharged firearm.
  • Determination of firing distances
  • All submitted garments will undergo a series of visual, microscopic, and chemical tests to determine if and where any gunpowder remains.
  • The submitted firearm will be test fired at various known distances towards a test fabric.
  • The resulting gunpowder patterns remaining on the test fabric will be compared to the original garment in order to determine a firing distance.

Packaging of Evidence

  • Air dry all garments prior to packaging.
  • Wrap each piece separately in paper or place in paper bag.

Reprinted with permission.

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