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Firearms and Toolmarks Information


Firearms Functionality

In many investigations, knowing if a firearm is capable of discharge is an important question to answer. The Firearms and Toolmarks Unit is able to verify if a firearm is capable of discharge and report such findings.

Image of Fired Gun



Bullet / Cartridge Case Comparison

During the firing process, microscopic markings are left on the bullet and cartridge case by the firearm. These markings are used to identify if a bullet or cartridge case was fired by a specific firearm; or if multiple bullets or cartridge cases were fired by the same unknown firearm, if no firearm is recovered.


Two pictures of bullet comparisons


General Rifling Characteristics Database Search

If no firearm is recovered, but a bullet is, a list of firearms that could have possibly fired that item can be generated by measuring the general rifling characteristics of the bullet and searching the FBI’s GRC Database.


Integrated Ballistics Identification System (IBIS)

The Firearms and Toolmarks Unit houses a BrassTRAX system, capable of accessing the National Integrated Ballistic Information Network (NIBIN). At this time, only cartridge cases are entered. Test fires from submitted firearms, as well as cartridge cases from crime scenes, are evaluated for entry into IBIS.


The following will be evaluated for entry into IBIS.

Semi-automatic pistols of the following calibers:

           22 LR / 22 Long Rifle

           25 Auto / 25 ACP

           32 Auto / 32 ACP

           380 Auto / 9mm kurz / 9mm Corto

           9x18 MAK / 9x18 Makarov

           9mm Luger / 9mm Parabellum

           357 SIG

           40 S&W / 40 Auto

           10mm Auto

           45 Auto / 45 ACP

Semi-automatic rifles of the following calibers:

           22 LR / 22 Long Rifle

           223 REM / 5.56x45mm (example: AR-15)

           7.62x39mm (example: AK-47)

           Rifles that fire any of the above pistol calibers

Pump-action shotguns

Semi-automatic shotguns


The following will not be evaluated for entry into IBIS.

Revolvers, single shot and/or break-open shotguns, lever action rifles, bolt action rifles or shotguns, antiques / muzzle loaders / blackpowder, or hunting rifle calibers (i.e. 30-06 SPRG, 7mm Mauser, 303 British, 308 WIN, 243 WIN).


Serial Number Restoration

Since 1968, all firearms manufactured in or imported into the United States must have a serial number on the frame. This serial number is often obliterated. Polishing and/or chemical means can be used to attempt to restore such obliterated serial numbers.


Image of Serial Number Restoration


Muzzle-to-Target Distance Determination

The Firearms and Toolmarks Unit uses visual and chemical means to establish an approximate distance between the muzzle end of the firearm to the target based on deposits of gunshot residue. This analysis requires the target material (i.e. shirt) and the firearm believed to have been used. Distance determination analysis does not measure the intent of the shooter at the time the deposits were made. This analysis is only performed when the distance is in question (i.e. homicide v. self-defense). Before such analysis is requested, the investigator should contact the Firearms and Toolmarks Unit.


Toolmark Comparison

Just as bullets and cartridge cases can be identified to a specific firearm, toolmarks can be identified to a specific tool. The Firearms and Toolmarks Unit will perform comparisons between unknown toolmarks from crime scenes to submitted tools, such as bolt cutters and a pad lock, or wire cutters and wire.