Consistent Particle
Definition
ASTM E1588 category: a particle containing two of the three primer elements (Pb-Sb, Pb-Ba, or Sb-Ba), or all three elements without spherical morphology. Supportive but not conclusive individually.
- Source standard
- ASTM E1588
- Element combos
- Pb-Sb, Pb-Ba, or Sb-Ba (two of three)
- Alternative route
- All three elements without spherical shape
- Evidentiary weight
- Supportive, not individually conclusive
Common questions
How does a consistent particle differ from a characteristic particle in GSR analysis?+
A characteristic particle contains all three primer elements, lead, antimony, and barium, fused in a spherical morphology consistent with primer combustion. A consistent particle contains only two of the three elements, or all three but without the spherical shape, so it carries less individual weight and is normally reported alongside particle counts rather than as a standalone finding.
Can a single consistent particle prove a person fired a gun?+
No. ASTM E1588 treats a lone consistent particle as supportive at best, since some of these element combinations can arise from sources other than firearm discharge, such as certain fireworks or industrial contacts. Examiners weigh the total particle population and morphology rather than any one particle.
Related terms
- Antimony Sulphide
- Sb2S3, the primary fuel in conventional primer formulations, burning rapidly in the presence of oxygen released by barium nitrate during ignition.
- ASTM E1588
- ASTM International standard practice for gunshot residue analysis by scanning electron microscopy with energy-dispersive spectrometry. Defines particle classification (characteristic, consistent-with, indicative), morphology...
- Automated Particle Search (APS)
- A software-driven SEM mode that scans the entire stub surface using backscattered electron contrast, flags particles above an atomic-number threshold, and triggers...
- Barium Nitrate
- Ba(NO3)2, the oxidiser in conventional primer formulations, decomposing thermally to release molecular oxygen that sustains the combustion of antimony sulphide fuel.
- Characteristic Particle
- ASTM E1588 category: a single particle in which Pb, Sb, and Ba are simultaneously detected by EDS, with morphology consistent with melt-and-quench...
- ENFSI EWG-GSR
- The European Network of Forensic Science Institutes Expert Working Group on Gunshot Residue. Produces best-practice manuals, proficiency test rounds, and guidance on...
- Lead Styphnate
- Lead trinitroresorcinate (Pb(C6H(NO2)3O2)), the primary explosive in conventional primer compounds. Co-oxidised with barium nitrate and antimony sulfide to produce the Pb-Ba-Sb triad...
- Melt-and-Quench Mechanism
- The physical process by which GSR particles form: primer components are vaporised at firing temperatures, condense into spherical droplets in the expanding...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...