Schyma Christian, Müller Rolf, Brenčičová Eva, Brünig Julia
Institute of Forensic Medicine, University of Bern, Bühlstrasse 20, CH-3012, Bern, Switzerland.
Criminal Investigation Service of the Cantonal Police Department of Bern, Nordring 30, 3013, Bern, Switzerland.
Forensic Sci Med Pathol. 2018 Jun;14(2):202-208. doi: 10.1007/s12024-018-9971-0. Epub 2018 Apr 3.
After contact shots to the head, biological traces can be found inside the barrel of the firearm. Experimental protocols to generate this sort of staining, using 12 cm gelatin cubes containing thin foil bags filled with acrylic paint, human blood, and radiocontrast agent, have been developed. Previous research on shots fired at a distance has shown the underlay sustaining these gelatin cubes has an influence on experimental results. This study was conducted to investigate the role of the sustaining base of the gelatin blocks during contact shots, and its influence on the staining result inside firearm barrels. Eighteen contact shots were performed using 22 LR, 32 ACP (7.65 Browning) and 9 mm Luger semi-automatic pistols. With each pistol, shots were fired onto six gelatin cubes; three placed upon a rigid platform and three upon an elastic underlay. The shots were recorded by a high-speed video camera as they penetrated the gelatin cube. Any staining present inside the firearm barrels after the shots were fired was documented by endoscopy. Cross sections of the gelatin blocks were then compared to the high-speed video. It was found that the nature of the staining inside the barrel was not influenced by the underlay sustaining the target model. In the experiment using a 9 mm Luger, the rigid counterfort provoked a visible distortion of the temporary cavity, but, cross sectional analysis of the gelatin cubes did not reveal a relevant influence of the sustaining underlay on the crack length in the gelatin. This could be explained by a secondary expansion of the temporary cavity left by the projectile as a consequence of subsequent inflow of muzzle gases.
在对头部进行接触射击后，可在枪支枪管内部发现生物痕迹。已经制定了实验方案来产生这种染色效果，使用含有装有丙烯酸漆、人血和放射性造影剂的薄箔袋的12厘米明胶立方体。先前对远距离射击的研究表明，支撑这些明胶立方体的底层对实验结果有影响。本研究旨在调查明胶块支撑底座在接触射击过程中的作用及其对枪支枪管内部染色结果的影响。使用22 LR、32 ACP（7.65勃朗宁）和9毫米鲁格半自动手枪进行了18次接触射击。使用每把手枪向六个明胶立方体射击；三个放置在刚性平台上，三个放置在弹性底层上。射击穿透明胶立方体时，由高速摄像机记录。射击后通过内窥镜检查记录枪支枪管内部出现的任何染色情况。然后将明胶块的横截面与高速视频进行比较。结果发现，枪管内部染色的性质不受支撑目标模型的底层的影响。在使用9毫米鲁格手枪的实验中，刚性支撑物导致了临时空腔明显变形，但是，对明胶立方体的横截面分析并未显示支撑底层对明胶中裂纹长度有相关影响。这可以通过由于枪口气体随后流入而导致弹丸留下的临时空腔的二次膨胀来解释。
