Coupon Accepted Successfully!


Forensic Ballistics

Deals with fire-arm ammunitions and the problem arising from use.
A. Firearm : Any instrument which discharges a missile by the expansile forces of gases produced by burning of an explosive substance.
B. Calibre Distance b/w two diagonally opp. Lands
C. Bore/Gauge of gun : used only for shot-guns.
: It is the no. of lead balls of equal size and weight that can be made from 454 gms of lead.
D. Choking : Constricting device at the muzzle end of shot-gun*
it lessens the rate of spread of shot after it leaves the muzzle.
E. Paradox gun When the muzzle end of the shot-gun is rifled.
F. Black Gun Powder potassium nitrate 75% +   sulphur 10% +     charcoal 15%
 (oxidising agent)           (increases density)        (fuel)
G. Smokeless
Gun Powder
1. Nitro cellulose (single base )
2. Nitro glycerine + nitrocellulose (double base)
3. Nitrocellulose+ nitroglycerine+ nitroguanidine (triple base)
They produce much less flame and smoke and are more completely burned.
H. PRIMERS : Lead peroxide + Lead styphanate + Tetrazane + Barium nitrate

A Modern Cartridge Consists of the Following

  1. The bullet itself, which serves as the projectile;
  2. The casing, which holds all parts together;
  3. The propellant, for example gunpowder or cordite;
  4. The rim, part of the casing used for loading;
  5. The primer, which ignites the propellant.  

Extra Edges: The basic features of cartridges used in guns. The primer, when struck by the firing pin, ignites the powder. It is the residue left by the primer that is characteristic for a fired round, because it leaves traces of lead, antimony, copper, and barium.

Test Used For Firearm Discharge Residues

  1. Harrison & Gilroy test : Detects the presence of Antimony , Barium & lead.
  2. Neutron Activation analysis: Detects the presence of Antimony & Copper.
  3. Atomic Absorption Spectroscopy: Detects Antimony, Barium, Copper
  4. Modified griess test: for nitrate
  5. Dithioximide test: for copper
  6. Sodium rhodizonate: for lead
  7. Scanning electron microscopy with X-ray analyser.
  8. Paraffin test (Dermal Nitrate Test) : Used to determine if the suspect has discharged a firearm. The blow back powder residue on the back of palm & the web of allleged firer’s hand were colected on paraffin cast & tested for nitrate using diphenylamine. Obsolete because of false positive results.

Trait of the Entry Wound



RIFLED Firearm

Singeing/ flame

Upto 45 cms

Upto 8cms

Blackening/ smoke/ carbon smudging/fouling

Upto 30 cms

Upto 30 cms

Tattoing/ unburned particles

Upto 60 – 90 cms

Upto 60 – 90 cms


Upto 2 m



Upto 2- 6 m




  1. Blackening is due to Smoke.
  2. Singeing is due to Flame.
  3. Tattoing is due to Unburnt powder discharged from the firearm weapon

Test Your Skills Now!
Take a Quiz now
Reviewer Name