- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- Introduction
- Objectives
- AFTE Knowledge and Ability Factors
- Powders and Residues
- Examination
- Distance Determination
- Significance of Results
- Contact Shot
- Nitrite Residues
- Vaporous Lead Residues
- Residues Consistent with the Passage of a Bullet
- Residues Consistent with the Discharge of a Firearm
- Interpretation Challenges
- Reproduction of Results
- Nitrite Residue Patterns
- Shot Patterning
- Chemical Testing
- Shot Pattern Reproduction
- Selected Bibliography
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Shot Pattern Reproduction
Home > Gunshot Residue and Distance Determination > Distance Determination > Shot Pattern Reproduction
Shot patterns produced using the same
12-gauge shotgun with shotshells
containing #4 shot pellets
The reproduction of shot patterns, as noted in the gunshot residues section, should employ the same shotgun and type of ammunition as used in the incident, per laboratory protocol. If a shotgun has a variable choke, the reproduction of shot patterns should be conducted with the firearm in the same condition as when it was received in the laboratory. Indexing the choke and barrel with a scribing tool prior to firing provides future reference.
A box of shotshells will produce shot patterns that may vary noticeably when used in the same firearm. Therefore, the same diameter of shot pattern may be produced at a number of different distances within a span of varying ranges. To develop a distance determination range, it is necessary to determine at what range a known-distance pattern is always smaller than an evidence pattern and at what range the known pattern is always larger.
At greater distances, stating a larger range is appropriate. For example, if testing yielded data that supported a firing distance of approximately thirty feet, a reasonable range for distance determination would be twenty-five to thirty-five feet. If the firing distance is shorter, for example approximately twenty feet, the range would be stated at seventeen to twenty-three feet. After the examiner tentatively establishes the extremes of the range, each extreme should be verified by a number of firings to ensure reliability.
