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Bureau of Criminal Apprehension

A Division of the Minnesota Department of Public Safety

Firearm and Toolmark Evidence

Tools, including firearms, bear both class characteristics(1) and individual characteristics(2) that may be transferred to surfaces they come into contact with.  Forensically significant toolmarks identified at crime scenes can be compared against suspected tools or firearms.  Such evidence can link the marks to a class of tools or firearm or, if sufficient markings are present, to one specific tool or firearm.  

  i.   Gunshot Residue Collection
 ii.   Trace Metal Detection
iii.   Sodium Rhodizonate test for lead
iv.   Silicone Based Casting Materials

From the Association of Firearm and Toolmark Examiners (http://www.afte.org/) Glossary #5: 

(1) Class Characteristics

Measurable features of a specimen which indicates a restricted group source. They result from design factors, and are therefore determined prior to manufacture.

(2) Individual Characteristics

Marks produced by the random imperfections or irregularities of tool surfaces. These random imperfections or irregularities are produced incidental to manufacture and/or caused by use, corrosion, or damage. They are unique to that tool and distinguish it from all other tools.