Azahidi, Azahiri
(2011)
Comparison of Action Marks on Cartridge Cases Discharged
from 9mm Walther P99 Models AS and QA Semiautomatic
Pistols on Repeated Firing.
Other.
Pusat Pengajian Sains Perubatan, Universiti Sains Malaysia.
(Submitted)
Abstract
A fireann identification expert sometimes find it difficult to draw conclusions when
comparing fired ammunitions found at the crime scene with the firearm that is recovered after
some time interval. During the period, the firearm might have been subjected to any changes
due to prolonged repeated firing. This project work investigated any changes and alterations
of the action marks recorded on the expended cartridge cases due to repeated firing of 9mm
Walther P99 semiautomatic pistols models Anti Stress (AS) (RMP 10248, RMP 10263) and
Quick Action (QA) (RMP 61077, RMP 61089, RMP 61100). Each pistol had been repeatedly
fired for at least 740 rounds, on the occasion of the shooting practice for police officers of
Kelantan State. Cartridge cases of every consecutive of 40th rounds were recovered.
Examination using Leica Forensic Solution Comparison (FS C) microscope under
magnification x 10 to x60 was conducted to observe class and individual characteristics
produced by each pistol. Class characteristics of AS and QA models showed many
similarities, since they are the variants of the same family of Walther P99. Positive
identification between the last cartridge case with the first cartridge case could be made based
on breech face marks, firing pin impressions, extractor marks and striation marks that were
found on the rim. The study had shown that prolonged repeated firing of guns may cause
some changes of action marks but the changes are not significant, hence identification could
be made.
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