Visualization of the powder pocket and its influence on staining in firearm barrels in experimental contact shots.

Schyma, Christian; Bauer, Kristina; Brünig, Julia; Schwendener, Nicole; Müller, R (2016). Visualization of the powder pocket and its influence on staining in firearm barrels in experimental contact shots. International journal of legal medicine, 131(1), pp. 167-172. Springer 10.1007/s00414-016-1419-z

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The powder pocket or soot cavity is a morphologic characteristic of a close contact shot. In a research project concerning staining inside the barrel, the influence of the powder pocket on these traces was investigated.According to the 'triple contrast method', thin pads containing a mixture of acrylic paint, radiocontrast agent and blood were glued on plastic boxes which were coated with a 3-4-mm-thick silicone layer. The containers filled with 10 % ballistic gelatine, were stored for at least 60 h at 4 °C. Thirty-three contact shots were realized using different pistols and 22 lr, .32 auto, .38 special and 9-mm Luger with different barrel length using subsonic, non-deforming ammunition.The documentation comprised endoscopy, high speed video and computer tomography (CT) of the target models. Using image analysis, the ballooning of the silicone coat was studied (lateral view projection).High-speed video confirmed the actual comprehension of the behaviour of muzzle gases in contact shots. The powder cavity rises in about 1.5 to 2 ms, preceding the maximum of the temporary cavity, and the powder pocket's collapse takes 2.5 to 3 ms.The size of the silicone dome increased with decreasing barrel length. Comparing semi-automatic pistols of 4 in. barrel length in the calibres, .32 auto and 9-mm Luger, there were no significant differences of the powder pocket size. Material transport was observed, against and perpendicularly to the shooting direction. CT showed undermining and gas inclusions inside the powder pocket. A correlation between amount and pattern of the staining inside the barrel and the volume of the powder pocket was not observed.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Service Sector > Institute of Legal Medicine
04 Faculty of Medicine > Service Sector > Institute of Legal Medicine > Forensic Medicine

UniBE Contributor:

Schyma, Christian; Bauer, Kristina; Brünig, Julia and Schwendener, Nicole

ISSN:

0937-9827

Publisher:

Springer

Language:

English

Submitter:

Antoinette Angehrn

Date Deposited:

10 Aug 2016 07:52

Last Modified:

12 Jan 2017 01:30

Publisher DOI:

10.1007/s00414-016-1419-z

PubMed ID:

27470317

Uncontrolled Keywords:

Backspatter; Contact shot; Powder pocket; Soot cavity; Suicide

BORIS DOI:

10.7892/boris.85646

URI:

https://boris.unibe.ch/id/eprint/85646

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