The surface coating of a random selection of firearms was examined and the results are given in Table 20.10. The elements detected in Table 20.10 do not fully reflect the wide range of elements mentioned in Chapter 15.
It is possible that such coatings could, on rare occasions, make a contribution to the elemental content of some of the particles, or could be deposited directly on to the hands from handling the firearm. Surface coatings have the potential to make a contribution, particularly from the cylinder gap area of revolvers and from the muzzle area of any type of firearm. These are the "exterior" areas subjected to the hot propellant gases, which may erode the surface coating. Mixtures containing selenium are used to repair surface coatings of firearms, and particles containing selenium are occasionally encountered in casework. Such particles can provide useful additional evidence. Homemade firearms are frequently painted black using household paints. Such coatings can flake and leave paint flakes on the hands or clothing (particularly pocket interiors), and this can provide very useful evidence.
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