非制式枪支射击自制底火子弹弹壳痕迹检验

由制式64式手枪改制的枪支,其射击弹头、弹壳上的痕迹位置、形态也因改制手法和部件的不同而存在差异,给检验增加了难度,利用其射击弹头、弹壳上的痕迹对发射枪支进行同一认定具有重要的意义。本案中,笔者在非制式64式手枪的拉壳钩上使用颜色标记,并对标记枪支发射的带有自制底火的改制弹壳进行检验,从而对拉壳钩在异常位置遗留的痕迹进行了确认,为使用异常位置拉壳钩痕迹进行发射枪支的同一认定提供了依据。     

射击弹壳上新生痕迹特征的检验

检验射击弹壳上的痕迹特征,常规方法主要是对枪弹在装弹、发射、抛壳等过程中枪支有关机件与弹壳对应部位在紧压贴合下产生相对运动和相互作用时在弹壳上形成的痕迹特征的检验。枪支的有关机件在弹壳上形成痕迹的形状、大小、位置以及它们的相互关系反映了枪支的结构特点,是据此认定发射枪种的种类特征;枪支机件在生产加工过程中和在使用过程中形成的轮廓异常及点、线状细小特殊的痕迹特征是认定发射枪支的个别特征。但是在实际检验中,经常遇到由于在射击过程中受到枪弹和各种射击因素的影响或者被破坏,使射击弹壳上供认定发射枪支的个别特…     

阳极氧化电解显现射击前弹壳上手印的研究

目的解决涉枪案件现场提取到的射击前的弹壳或留存在弹夹中的弹壳上手印的提取。方法采用电化学方法中阳极氧化电解方式显现黄铜弹壳或紫铜弹壳上的手印。结果利用H68黄铜片和紫铜片的等效性能,摸索出了阳极氧化电解弹壳上手印上检测方法,并应用于射击前黄铜弹壳或紫铜弹壳上手印的显现。结论实验发现,所形成的检测方法能够有效的显现出射击前黄铜弹壳或紫铜弹壳上手印,同时依据实验现象分析出了阳极氧化显现黄铜弹壳或紫铜弹壳上手印的原理。     

2005式9mm警用转轮手枪射击弹壳痕迹研究

目的 研究2005式9mm警用转轮手枪射击弹壳痕迹,为警用转轮手枪射击弹壳痕迹检验鉴定提供理论依据.方法 预实验中选取10把警用转轮手枪以单动、联动方式分别射击收取弹壳样本,观察识别射击弹壳上各个痕迹的位置、形态及相互关系;补充验证实验中选取其中5把警用转轮手枪以单动方式分别进行射击实验,完善、验证预实验中得出的结论.结果警用转轮手枪射击弹壳上的烟垢痕迹、弹底窝痕迹及击针头痕迹的分布位置、形态具有规律性,具备检验鉴定价值.结论 利用弹底窝痕迹、烟垢痕迹结合击针头痕迹,可以实现射击弹壳的准确定位;利用烟垢痕迹、弹底窝痕迹及击针头痕迹具有推定弹壳先后射击顺序的可能性;通过弹底窝痕迹、击针头痕迹的细节特征比对,可以实现射击枪支的同一认定.     

六四式手枪弹壳发射顺序的研究

目的　研究六四式手枪射击弹壳的排序规律。方法　对已知顺序实弹射击取样 ,显微观察弹壳上发射过程中形成的痕迹 ,通过统计、归纳 ,从中发现与排序有关的痕迹特征 ,及其与发射顺序之间的关系。结果　研究发现 ,因子弹发射顺序不同 ,弹壳上出现的抛壳挺痕的高低 ,弹底边缘压擦痕的有无轻重 ,推弹突笋痕迹的形状位置与发射顺序有关。结论　根据抛壳挺等痕迹的具体形态 ,及变化特点 ,可判断出六四手枪弹壳的发射顺序。     

八五式7.62mm轻型冲锋枪射击弹壳痕迹初探

通过对八五式轻型冲锋枪射击弹壳的初步观察分析,介绍了该枪射击弹壳留痕的位置、形态、大小等特征,并与五四式手枪、七九式轻型冲锋枪弹壳留痕特征进行了比较。     

试析射击弹头、弹壳痕迹特征在枪弹痕迹鉴定中的价值

枪支发射时,在射击弹头、弹壳上将形成多种射击痕迹,对其进行分析检验可以帮助判明射击距离、射击方向、射击者和被害人所处位置,为侦查提供线索;可以确定犯罪行为人作案时所用枪支、子弹的类型;还可以根据弹头、弹壳上的痕迹,对嫌疑枪支进行同一认定,以认定现场上发现的弹头和弹壳是否嫌疑枪支所发射,为侦查诉讼提供证据.本文将根据射击弹头、弹壳痕迹特征的特定性及稳定性进一步研究其在枪弹痕迹鉴定中的价值.     

95式5．8mm自动步枪射击弹壳上痕迹的研究

目的研究95式5.8mm自动步枪射击弹壳上痕迹的检验价值。方法用10支95式5.8mm自动步枪分别射击50发,对收集的500枚射击弹壳在显微镜下观察测量。结果弹壳上痕迹反映普遍较浅,痕迹具有特殊性。结论95式5.8mm自动步枪射击弹壳上痕迹具有一定的同一认定价值。     

12号五连发套筒猎枪射击弹壳上痕迹的探讨

本文主要论述了12号五连发套筒猎枪射击弹壳上托弹板划痕、击针头痕、弹底窝痕、上下拉壳钩痕、闭锁保险机碰痕等痕迹的形成及其分布部位、形态、出现率和细微特征的稳定性,为利用弹壳射击痕迹,认定发射枪支提供了科学依据.     

根据击针偏斜确定弹底窝擦痕的位置

在实际验枪工作中,发现同一支枪发射的子弹,有的弹壳底部出现弹底窝擦痕,有的则未出现。对于那些没有出现弹底窝擦痕的射击弹壳,如何确定其擦痕位置,是查对枪弹档案的重要一环。本文通过大量枪支射击,对五四类弹壳进行了认真细致的观察、分析和检验,从而得出击针偏斜与弹底窝擦痕之间的数量统计关系。     

Image matching algorithms for breech face marks and firing pins in a database of spent cartridge cases of firearms

On the market several systems exist for collecting spent ammunition data for forensic investigation. These databases store images of cartridge cases and the marks on them. Image matching is used to create hit lists that show which marks on a cartridge case are most similar to another cartridge case. The research in this paper is focused on the different methods of feature selection and pattern recognition that can be used for optimizing the results of image matching.The images are acquired by side light images for the breech face marks and by ring light for the firing pin impression. For these images a standard way of digitizing the images used. For the side light images and ring light images this means that the user has to position the cartridge case in the same position according to a protocol. The positioning is important for the sidelight, since the image that is obtained of a striation mark depends heavily on the angle of incidence of the light. In practice, it appears that the user positions the cartridge case with +/-10 degrees accuracy.We tested our algorithms using 49 cartridge cases of 19 different firearms, where the examiner determined that they were shot with the same firearm. For testing, these images were mixed with a database consisting of approximately 4900 images that were available from the Drugfire database of different calibers.In cases where the registration and the light conditions among those matching pairs was good, a simple computation of the standard deviation of the subtracted gray levels, delivered the best-matched images. For images that were rotated and shifted, we have implemented a "brute force" way of registration. The images are translated and rotated until the minimum of the standard deviation of the difference is found. This method did not result in all relevant matches in the top position. This is caused by the effect that shadows and highlights are compared in intensity. Since the angle of incidence of the light will give a different intensity profile, this method is not optimal.For this reason a preprocessing of the images was required. It appeared that the third scale of the "à trous" wavelet transform gives the best results in combination with brute force. Matching the contents of the images is less sensitive to the variation of the lighting.The problem with the brute force method is however that the time for calculation for 49 cartridge cases to compare between them, takes over 1 month of computing time on a Pentium II-computer with 333MHz. For this reason a faster approach is implemented: correlation in log polar coordinates. This gave similar results as the brute force calculation, however it was computed in 24h for a complete database with 4900 images.A fast pre-selection method based on signatures is carried out that is based on the Kanade Lucas Tomasi (KLT) equation. The positions of the points computed with this method are compared. In this way, 11 of the 49 images were in the top position in combination with the third scale of the à trous equation. It depends however on the light conditions and the prominence of the marks if correct matches are found in the top ranked position. All images were retrieved in the top 5% of the database. This method takes only a few minutes for the complete database if, and can be optimized for comparison in seconds if the location of points are stored in files.For further improvement, it is useful to have the refinement in which the user selects the areas that are relevant on the cartridge case for their marks. This is necessary if this cartridge case is damaged and other marks that are not from the firearm appear on it.     

Automated region segmentation on cartridge case base

One of the significant problems encountered in criminology studies is the successful automated matching of fired cartridge cases, on the basis of the characteristic marks left on them by firearms. An intermediate step in the solution of this problem is the segmentation of certain regions that are defined on the cartridge case base. This paper describes a model-based method that performs segmentation of the cartridge case using surface height image of a center fire cartridge case base. The proposed method detects the location of the cartridge case base center and specific circular contours around it iteratively by projecting the problem to a one-dimensional feature space. In addition, the firing pin impression region is determined by utilizing an adaptive threshold that differentiates impression marks form primer region surface. Letters on the cartridge case base are also detected by using surface modeling and adaptive thresholding, in order to render the surface comparison operation robust against irrelevant surface features. Promising experimental results indicate the eligibility of the proposed method to be used for automated cartridge case base region segmentation process.     

79式微型冲锋枪子弹射击顺序的研究

目的研究79式微型冲锋枪发射子弹的排序。方法对已知顺序实弹射击取样,扩大观察弹头、弹壳上发射过程中形成的痕迹,通过统计、归纳,从中发现与排序有关的痕迹特征。结果壳体肩部圆点痕,弹底边缘压擦痕、拉壳钩痕与发射顺序有关。结论壳体肩部圆点痕、弹底边缘压擦痕等痕迹的有无、位置及轻重程度,对判断79式微型冲锋枪弹壳发射顺序有较可靠的参考价值。     

Determining an Optimal Sequence for Chemical Development of Latent Prints on Cartridge Casings and Shotgun Shells*,†

Abstract: In developing latent prints on cartridge casings and shotgun shells, multiple chemical processes should be used in order to obtain the best results. In Phase I, this study established an optimal chemical sequence for both Brass and Nickel cartridge casings based on six sequences involving four chemicals: Cyanoacrylate, Black Powder, Rhodamine 6G and Acidified Hydrogen Peroxide. Phase II was a validation study of Phase I involving a random sample of both Brass and Nickel cartridge casings, which were processed according to the determined optimal sequences. In addition, ribbed shotgun shells were processed under Phase I results and determined to be dependent upon the utilization of a CrimeScope at 515 nm. Consideration should be given to the type of cartridge case being examined. Although limitations exist, some chemical sequences undeniably work better than others. All photographs were manipulated with Adobe^® Photoshop^®. All results were verified by a senior latent print examiner.     

Three-Dimensional Analysis of Cartridge Case Double-Casts

Due to the shot-to-shot variability in tool mark reproduction on fired cartridge cases, a method of replication is needed for the creation of training and testing sets. Double-casting is one method that has been used for this application, but the accuracy and variability of this method needs to be characterized. Three firearms were used to fire 25 cartridges each to create the master cartridge cases. The double-casting method consists of creating a silicone mold of the master cartridge case. A plastic resin mix is then poured into the mold to create the double-cast reproduction. Fifteen double-casts of each of the 75 fired cartridge cases were created across different silicone molds to analyze within- and between-mold variability. The master cartridge cases and double-casts were scanned with a confocal microscope (Sensofar® S neox) to create three-dimensional representations of the surfaces. Two similarity metrics were used for the objective comparison of the double-casts to their master cartridge cases: the areal correlation coefficient (ACCF_MAX) and the number of congruent matching cells (CMC). The ACCF_MAX and CMC data, along with visual examinations, showed that the double-casting method produces accurate reproductions. Within-mold variability was found to be minimal, and between-mold variability was low. These results illustrate that double-casting can be applied for training and testing purposes.     

弹壳表面指纹的显现方法

使用硝酸银溶液化学反应原理显现枪案现场弹壳表面的指印是一种行之有效的方法。此方法同样可用于子弹、铜钥匙等铜金属表面指纹的显现,效果良好。     

Automated detection of regions of interest in cartridge case images using deep learning

This paper explores a deep-learning approach to evaluate the position of circular delimiters in cartridge case images. These delimiters define two regions of interest (ROI), corresponding to the breech face and the firing pin impressions, and are placed manually or by an image-processing algorithm. This positioning bears a significant impact on the performance of the image-matching algorithms for firearm identification, and an automated evaluation method would be beneficial to any computerized system. Our contribution consists in optimizing and training U-Net segmentation models from digital images of cartridge cases, intending to locate ROIs automatically. For the experiments, we used high-resolution 2D images from 1195 samples of cartridge cases fired by different 9MM firearms. Our results show that the segmentation models, trained on augmented data sets, exhibit a performance of 95.6% IoU (Intersection over Union) and 99.3% DC (Dice Coefficient) with a loss of 0.014 for the breech face images; and a performance of 95.9% IoU and 99.5% DC with a loss of 0.011 for the firing pin images. We observed that the natural shapes of predicted circles reduce the performance of segmentation models compared with perfect circles on ground truth masks suggesting that our method provide a more accurate segmentation of the real ROI shape. In practice, we believe that these results could be useful for firearms identification. In future work, the predictions may be used to evaluate the quality of delimiters on specimens in a database, or they could determine the region of interest on a cartridge case image.     

Fatality During Servicing of Fire Extinguisher

Fire extinguisher is an integral part of emergency responses to small fires. Different types of fire extinguisher exists; cartridge‐based fire extinguisher is commonly used. Despite their intended use for safety, such devices can become dangerous if not properly handled or maintained. This case report describes the death of a soldier from the explosion of a cartridge‐based fire extinguisher during routine servicing. The case is the first reported in the medical literature. A safety device like fire extinguisher can become dangerous if not handled with care and due steps should be taken for the maintenance of such devices before being operated in the public domain.