As a forensic discipline, the essential protocol for firearms identification is the microscopic comparison and potential identification of fired bullets as having been fired from the barrel of the same firearm.
The foundation for this technique is based on the following principles:
- The rifling in the barrel of a firearm bears unique microscopic characteristics due to manufacturing processes, use, and abuse.
- These characteristics mark the bearing surfaces of bullets when fired through the barrel.
- These individual characteristics are reproducible and identifiable with a particular firearm.
Comparison microscopy is used to establish identification and involves one of the following situations:
|Recovered firearm without related evidence
Obtain test bullets for later comparison by test firing the recovered firearm.
|Recovered firearm with related evidence
Obtain test bullets from evidence firearm and compare to recovered bullet to determine if the recovered firearm fired the evidence bullet.
|Recovered bullets without related firearm
Perform intercomparison to determine if recovered bullets are related to a single firearm.
A worksheet for these comparisons should be completed according to laboratory protocol.
Click here to read a sample forensic worksheet and report -
Bullet Comparison and Identification