Examination of Firearms Review: 2007 to 2010 - Interpol

2.6 Training Material & Books
Since 2008, the NFSTC put a firearms examiner training course on line (112).
This course was made in collaboration with AFTE members and based on the
AFTE training manual. Also recently released to the press was a new edition of
Modern Scientific Evidence: The Law and Science of Expert Testimony. A
chapter of this book is dedicated to Firearms and Toolmark Identification (113).
Brian J. Heard published the second edition of his book entitled “Handbook of
Firearms and Ballistics – Examining and Interpreting Forensic Evidence” (114).
3 Firearms – Chemistry
During discharge from a firearm, primer and gunpowder residues as well as
metal particles from the projectile and the cartridge case are escaping from the
muzzle and other openings of the firearm. These residues are referred as primer
residue, firearm discharge residue or gunshot residue (GSR).
3.1 Inorganic GSR
Scanning Electron Microscopy – Energy Dispersive X-ray microanalyses
(SEM/EDX) still is the method of choice for the identification of inorganic GSR on
samples. This technique is well adapted to the detection of small particles
containing heavy metals such a lead, barium and antimony coming from primer
with a "conventional" composition.
3.1.1 Lead-free ammunition
However more and more primers do not contain one (or more) of these three
elements. Because of the "uncharacteristic" composition of the residues,
analysis of these types of ammunition by SEM/EDX will often be falsely negative.
Fortunately, in reality the "memory effect" of the gun produces sufficient
"contaminating" classic particles to make a good identification still possible. The
use of special tagging compounds and metals in the cartridge is nevertheless
highly recommended. Automatic analysis system parameters must be adapted
since standard runs will miss these particles or yield inconclusive results. Taking
note of these considerations, Martiny et al. (115) performed a thorough
characterisation of the gunshot residues produced from Brazilian lead-free
ammunition by SEM/EDX analysis. The "CleanRange" lead-free ammunition
made by Brazilian CBC was originally developed considering health issues with
lead-containing classic ammunition, for instance when used in police shooting
ranges. They have since made their entry in the general population of
ammunition used in Brazil. In fact, at this moment two generations of lead-free
CBC ammunitions are now available. The first generation, mostly used in
Europe, is almost exclusively made of strontium, together with smaller amounts
of sodium, potassium and iron. The morphology is mostly consistent with GSR
27