Examination of Firearms Review: 2007 to 2010 - Interpol

marks have a tendency to be over marked as the bullet makes its way down the
barrel during firing. The questioned cartridge case should be placed on base
down on the pad of leather or rubber to prevent damage to the toolmarks
imparted during the previous firing event. A reload bullet must be placed nose
first into the cartridge case. The bullet can now be tapped into the cartridge case.
After indexing, use an inertia bullet puller to extract the bullet from the cartridge
case. Bennett wrote a case report on identifying a bullet to a cartridge case (22).
Striae can originate from case mouth burrs but it will depend on the relative
hardness of bullet jacket versus cartridge case material if markings are
transferred. Also Barnes produced a case report on the same subject (23). In a
presumably cover-up murder case, it became necessary to evaluate cartridge
case mouth crimp impressions on fired bullets. The easiest way was to compare
castings from the inside of the case mouth directly to the fired bullets. In a case
report, Clow looks at identifying bullets and cartridge cases to a single unknown
firearm using magazine marks (24). Upon examination of cartridge cases and
bullets from a homicide scene, it became apparent that both bear gross
markings. The markings on the cartridge case were determined to be magazine
markings. They were very distinct and identifiable and some cartridge cases
even had multiple markings. At the stage were the bullets were compared, it was
noted that the gross markings on bullets and cartridge cases could be positively
inter-compared. Also the sequence of the multiple markings was in good
correspondence, leading to the conclusion that both bullets and cartridge cases
could be identified to the same gun.
Siso and Kasachesko too report on identifiable magazine marks on the base of
cartridge cases, fired from a FN HP pistol (25). It was discovered that the
markings originate from the back top area of the magazine. The striated mark’s
appearance depends directly on the shape and inside surface at the rear of that
area. Also, the method of loading has an influence on the appearance of the
markings.
Koffman and Hocherman introduce class and individual chamber impression
markings on cartridge cases fired by FN1910/1922 pistols (26). These
characteristics, produced during the discharge process, can be found in three
areas on the forward section of the rim. As class characteristics they can assist
the firearms examiner to identify the type of firearm used. As individual
characteristics they can be used as an excellent source for microscopic
comparison examinations.
2.1.4 Proficiency testing
ENFSI send round a 2 nd edition of their proficiency test. The FAID2009,
distributed early 2010, consisted of 10 sets of bullets and cartridge cases. Each
set consisted of 2 known reference elements and third questioned element that
had to be compared to the references. The proficiency test was made from
castings (see also reference (55)).
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