Bullet hole perimeters

Tests were also conducted to determine if it was possible to identify the bullet jacket material from examination of the bullet hole perimeter. The ammunition used is given in Table 20.12 and the test results are presented in Table 20.13. 

Table 20.12 Bullet Hole Perimeter Test Ammunition...

A surprising result was the amount of mercury remaining on the bullet after it had passed through a wad of filter paper and the bullet recovery medium. Mercury was also readily detectable in the bullet hole perimeter tests (Table 20.12 and Table 20.13). 

The possibility of relating bullet damage to a particular round of ammunition by chemical comparison of the deposit on the bullet hole perimeter with the deposit on the spent bullet should be investigated. 

The residue on the surface of a discharged bullet appears to originate from the base of the bullet itself, from the primer, and from inorganic additives to the propellant. Firings numbered 8,21,34, and 35 had lead-free primers yet lead was detected on the perimeter of the bullet holes. Ammunition with barium-free primers gave barium on the perimeter. 

Only one of the two nickel-jacketed bullets, number 43, gave nickel on the perimeter of the bullet hole. Nickel was frequently detected from nonnickel-coated bullets. This is a surprising result which demonstrates that the presence of nickel cannot be used to identify the use of a nickel-jacketed bullet. The origin of the nickel is unknown but it may have originated from the primer cup coating. 

It is interesting to note that in all tests in which mercury was present in the primer, it was detected on the perimeter of the bullet hole. The unjacketed lead bullets all gave a large quantity of lead on the perimeter, although this was not confined to unjacketed bullets. The copper results were similarly confusing. 

Overall, the possibility of determining the bullet jacket material from the residue around the bullet hole does not appear to be feasible using FAAS. However, FAAS reliably detects elements associated with firearm discharge on the perimeter of the bullet hole and is a very useful method for confirming bullet damage. 

Table 20.13 Elemental Levels (ng) on Perimeter of Bullet Hole...

Using the same ammunition type, the amount of mercury deposited on the perimeter of a bullet hole was then determined. Results are given in Table 22.6. 

The Northern Ireland Forensic Science Taboratory (N1FST) was involved in the assessment of such ammunition for the police, and tests were conducted to compare lead levels using Nyclad and conventional ammunition. Unfortunately, the tests results did not survive the terrorist explosion at the laboratory in September 1992, but the overall conclusion was that the claims made relating to the reduction of lead were more than justified. (Other tests involving the examination of the perimeter of bullet holes in cloth that were caused by Nyclad bullets revealed that cobalt was repeatedly and readily detected by FAAS.)... 

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