Propellant
Definition
The chemical charge that burns rapidly inside the case to generate the gas that drives the projectile down the barrel. Black powder historically, smokeless powders today.
- Function
- Burns to generate propulsive gas behind projectile
- Historic type
- Black powder (potassium nitrate, charcoal, sulfur)
- Modern type
- Smokeless powder, nitrocellulose-based
- Forensic residue
- Unburned and partially burned particles found in GSR analysis
Common questions
Why do examiners distinguish black powder from smokeless powder residue?+
The two leave different chemical and particulate signatures at a scene: black powder residue is heavier, visibly smoky, and largely inorganic, while smokeless powder leaves organic nitrocellulose traces, which affects both the swabbing method and the analytical technique chosen.
Does propellant type affect how far gunshot residue travels?+
Yes. Black powder produces a larger, closer-range residue pattern because it burns less completely, whereas smokeless powder burns more efficiently and produces a finer, more dispersed pattern, which examiners factor into distance estimation.
Related terms
- Ammunition
- The cartridge assembly fired by a firearm. Comprises case, primer, propellant and projectile. Defined under Section 2(1)(b) of the Arms Act 1959...
- Bore / Caliber
- Bore is the internal diameter of the barrel. Caliber is that diameter expressed in inches (.32,.38) or millimetres (9 mm, 7.62 mm)....
- Cartridge
- The complete round of ammunition: case plus primer plus propellant plus projectile, assembled as a single unit for breech loading.
- Firearm
- A barrelled weapon that launches a projectile by the rapid expansion of gas from a confined burning propellant. Includes handguns, rifles and...
- Primer
- The small explosive cup at the base of a cartridge that ignites the propellant. Conventional primers use lead styphnate, barium nitrate and...
- Projectile
- The object expelled from the barrel. Single bullet in rifled arms, multiple pellets or single slug in shotguns.
- Rifling
- The helical groove pattern cut into a firearm barrel that imparts spin to the bullet, stabilising it in flight. Rifling lands and...