Forensic Ballistics: Ricochet, Dispersion and Accidental Discharge

UGC-NET Forensic Science Unit V hard-band drill on ricochet physics, shotgun pellet dispersion, and accidental-discharge mechanics. Calibrated scenario questions on the angle of incidence and angle of departure on hard surfaces, the critical angle above which a bullet penetrates rather than ricochets, lead and copper skid marks on impact surfaces, mushrooming and base deformation as ricochet indicators, and trace transfer to the substrate. The shotgun pattern segment covers cylinder, improved cylinder, modified, and full choke constrictions in thousandths of an inch, the 30-inch circle benchmark at 40 yards, and pattern density calculations for range estimation under Saferstein and Heard arithmetic. The accidental-discharge segment covers ANSI/SAAMI drop tests in the six standard attitudes, sear wear and sear engagement angle, hammer-block and transfer-bar safety mechanisms with the Ruger lineage, and double-action trigger-pull benchmarks and sear-release points across action types. The investigation segment covers scene reconstruction with trajectory rods and lasers, the reconciliation of witness statements with ballistic evidence, and expert opinion under Section 45 of the Indian Evidence Act 1872 and Section 39 of the Bharatiya Sakshya Adhiniyam 2023.

For MSc Forensic Science aspirants, NFSU PhD entrance candidates, UGC-NET Paper II Unit V test-takers, and ballistic-examiner trainees at central and state FSLs preparing for the case-reconstruction segment of the qualifying examination.

Topics covered:

• Ricochet physics: angle of incidence, angle of departure, critical angle, surface hardness
• Ricochet evidence: Pb and Cu skid marks, mushrooming, base deformation, trace transfer
• Shotgun choke types: cylinder, improved cylinder, modified, full, constriction values
• Pattern density calculations: 30-inch circle at 40 yards, range estimation arithmetic
• Accidental discharge: ANSI/SAAMI drop tests, sear wear, hammer block, transfer bar
• Double-action analysis: trigger pull weight, sear release point, safety failure modes
• Scene reconstruction: trajectory rods, laser methods, witness-evidence reconciliation
• Expert opinion under Section 45 IEA 1872 and Section 39 BSA 2023 on ballistic findings

Hard band; expect 30–40 percent accuracy on first attempt. Allow 30 minutes.