Characteristic GSR Particle (ASTM E1588-20)
Definition
A particle containing lead, barium and antimony together by SEM-EDS, with spherical morphology and size in the 0.5-10 micrometre range. The highest-specificity category for primer discharge identification.
- Standard
- ASTM E1588-20
- Elements present
- Lead, barium, antimony together
- Detection method
- SEM-EDS
- Size range
- 0.5-10 micrometres
Common questions
Why is this the highest-specificity GSR category?+
Finding lead, barium, and antimony together in one particle with the characteristic spherical melt-and-quench morphology is far less likely to arise from an unrelated source than any single element alone, so it carries the strongest weight in a primer discharge conclusion.
What does spherical morphology add beyond the elemental composition?+
The spherical shape reflects rapid melting and cooling consistent with the conditions inside a discharging firearm's primer, so an EDS hit with the wrong morphology is treated with more caution than one matching both composition and shape.
Related terms
- ASTM E1588-20
- ASTM International standard guide for gunshot residue analysis by SEM-EDS. Defines characteristic, consistent, and commonly-associated particle categories and sampling, analysis, and reporting...
- Automated SEM-EDS
- A robotic scanning electron microscopy workflow using backscattered electron imaging for morphometric screening and automated EDS acquisition for elemental classification. Reduces analysis...
- DDNP (Diazodinitrophenol)
- A lead-free primary explosive used in some lead-free primer formulations. Produces strontium-antimony or tin-containing GSR particles depending on the oxidiser used.
- 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...
- Organic GSR (OGSR)
- Propellant-derived residues including nitroglycerin, 2-NDPA, 4-NDPA, ethyl centralite and nitrocellulose fragments. Analysed by HPLC or GC-MS, independent of the inorganic SEM-EDS workflow.
- SINTOX
- A lead-free, heavy-metal-free primer formulation developed by DAG (Deutsche Ammunitions- und Geschossfabrik) and Geco in Germany in the 1990s-2000s, replacing lead styphnate...
- Ternary Diagram (Pb-Ba-Sb)
- A triangular compositional plot with Pb, Ba and Sb at the three vertices. Particles from conventional primer discharge cluster in the centre;...