Terminology: Gunshot Residue Analysis
Airbags |
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Safety devices found in motor vehicles that are deployed at the time of a collision to prevent impact of the driver/passenger against the vehicle’s interior structure; rapidly inflates using primer similar to the kind found in firearms.
Bullet |
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The projectile that is contained within a cartridge.
Cartridges |
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According to the Criminal Code of Canada a cartridge is anything that contains a projectile that is designed to be discharged from a firearm; this includes caseless cartridge and a shot shell; a complete unit of ammunition with 4 main components: primer, case, propellant, and projectile.
Cycle of operation
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The process through which a firearm is discharged.
- Cocking: Process used to cock the firing pin/hammer to allow striking of the primer.
- Loading: Process that loads a cartridge from the magazine to the chamber.
- Firing: Process that allows the primer at the base of the cartridge to be impacted by the firing pin and ignite the powder.
- Extraction: Process that allows the discharged cartridge case to be removed from the chamber.
- Ejection: Process that removes the discharged cartridge case from the firearm and cocks the firing pin/hammer for the next round.
Distance determination
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A technique used to determine the distance between the muzzle and the target surface at the time of discharge by studying the discharge patterns made by the specific firearm at different known distances and comparing them to the pattern seen in the questioned evidence.
Firing angle
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The angle between the firearm and adjacent flat surface that is in the same plane.
Firing pin
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The part of the firearm mechanism that strikes the primer of the cartridge to initialize the firing process in the cycle of operation.
Gunpowder |
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A low order explosive that is designed to rapidly expand upon ignition by the primer, within a cartridge, to propel the projectile down the barrel and out the muzzle of a firearm.
Gunshot Residue (GSR)
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Particulate material that is deposited after a firearm has been discharged; consists of burned and unburned components of the primer. Suspected GSR is analyzed by an SEM-EDX to determine the elemental composition and morphology (shape) of the particulates.
High order explosives
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Explosives that contain oxygen and nitrogen and very quickly produce high temperatures and have a rapid release of gas; contain two main types: primary and secondary.
Low order explosives
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Explosives that rapidly combust, at a rate slower than the speed of sound; propellants, gunpowder in firearms, and pyrotechnic devices fall under this category.
Primer |
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A primary high order explosive designed to ignite by shock and used to ignite the gunpowder within a cartridge.
Pyrotechnic devices
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Any device that is designed to produce special effects upon ignition, such as designs/colours/etc.; commonly referred to as fireworks.
Scanning Electron Microscopy – Energy Dispersive X-Ray (SEM/EDX) analysis
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A high-resolution microscope that can magnify objects up to 10,000x and provide information on the object’s chemical composition. Unlike conventional light microscopes that use visible light for imaging purposes, SEM uses electrons instead.
Stubs
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A component of the GSR collection kit, it is an aluminum disk (stub) that is covered with double-sided tape. A stub is dabbed on surfaces suspected to contain GSR for collection purposes.
A primary high order explosive designed to ignite by shock and used to ignite the gunpowder within a cartridge.
Anything that contains a projectile that is designed to be discharged from a firearm; this includes caseless cartridge and a shot shell; a complete unit of ammunition with 4 main components: primer, case, propellant, and projectile.
A component of the cartridge that is the portion of the cartridge that takes flight when firing a firearm; can be a bullet, slug, or any component used to be propelled upon discharge.
The chemical composition that generates gas when ignited by the primer. The gas propels the projectile(s). Also known as gunpowder.
A part of a repeating firearm that stores the cartridges and consists of a mechanism that allows the loading of the cartridge into the chamber of the firearm.
It is a cavity before the barrel where the ammunition is first loaded before being fired.
The part of the firearm mechanism that strikes the primer of the cartridge to initialize the firing process in the cycle of operation.
A low order explosive that is designed to rapidly expand upon ignition by the primer, within a cartridge, to propel the projectile down the barrel and out the muzzle of a firearm.
Any barreled weapon from which any shot, bullet or other projectile can be discharged which is capable of causing serious bodily injury or death to a person and includes any frame or receiver of such a barreled weapon or anything that can be adapted for use is classified as a firearm.
The opening at the end of the barrel from where the bullet or shot emerges and leaves the firearm.
The process through which a firearm is discharged.
Explosives that rapidly combust, at a rate slower than the speed of sound; propellants, gunpowder in firearms, and pyrotechnic devices fall under this category.
A hollow tube through which the projectile travels after being discharged; may contain rifling.
Scanning Electron Microscopy - Energy Dispersive X-Ray Analysis. A high-resolution microscope that can magnify objects up to 100,000x and provide information on the object's chemical composition.
Any device that is designed to produce special effects upon ignition, such as designs/colours/etc.; commonly referred to as fireworks.
Explosives that contain oxygen and nitrogen and very quickly produce high temperatures and have a rapid release of gas; contain two main types: primary and secondary.
A subatomic particle that is negatively charged and is found revolving around a central nucleus.
Gunshot Residue. Particulate material that is deposited after a firearm has been discharged; consists of burned and unburned components of the primer.
