- 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
Powders and Residues
Home > Gunshot Residue and Distance Determination > Powders and Residues
Firearm discharging
Burned or partially burned bullet propellants and other gunshot residues are expelled from the muzzle during the firing process and can be used to determine the distance of a muzzle from a garment or other surface at the time of discharge.
Click here to read more about propellants in Module 03.
When a firearm discharges, the burning of the propellant powder immediately generates a large amount of heat and gas inside the cartridge, providing the pressure required to expel the bullet.
Gunshot residues are composed of the following:
- Primer residues from the combustion of the cartridge priming mixture when the primer was struck by the firing pin
- Residues resulting from the burning of the propellant
- Material generated by the interaction of the bullet with the inside of the barrel
- Unburned and partially burned powder
