An Investigation into Whether or Not the Class and Individual Characteristics of Five Turkish Manufactured Pistols Change During Extensive Firing

Abstract:  In order to assess whether or not the class and individual characteristics of a firearm change over time, five different makes of Turkish self-loading pistol were tested and were each fired a large number of times. The class and individual characteristics were identified for each pistol and the first fired cartridge case was compared with the subsequent consecutive 250th fired cases for each pistol. It was found that there were slight changes in some of the individual and class characteristics; however, this was not statistically significant and did not affect the ability of the firearms examiner to match the first fired case to the last fired case for each firearm tested.     

Experimental evaluation of the impact of seating depth variations on observed marks on primers

Although the examination of bullet and primer striae patterns is still a very important task in forensic ballistics, a fundamental explanation or theoretical model for reasoning about the (ir)reproducibility of the observed marks is still non-existing. More specifically, it is still unclear which ammunition production or firing condition parameters may play an important role in the striae and marks formation process. From a practical point of view this situation is unfortunate because a proper knowledge of these parameters and conditions could help underpin and explain certain differences found in actual casework investigations. Additionally, a proper understanding of these issues could allow examiners to select or develop a near-optimal test firing procedure by using more detailed and controlled variations of certain intra- and/or inter-ammunition parameters than the ones that are in use today. In this paper, we discuss the results of an experiment aimed at evaluating the impact of primer seating depth variations on observed primer striae and other marks. First, three sets of cartridge cases with different seating depth intervals were selected. Second, each of these sets were fired consecutively using a selected pistol. Finally, the cartridge cases were examined using both traditional optical microscopes and three-dimensional (3D) profilometer techniques. The results reported in this paper show that in our experiments no important impact of the initial primer seating depth on the observed primer striae patterns could be found, but that the firing pin impression does seem to change if the initial seating depth is larger than a certain threshold.     

Confocal microscopy analysis of breech face marks on fired cartridge cases from 10 consecutively manufactured pistol slides

Recent publications from the National Academy of Sciences have called for additional foundational research in the field of firearm and toolmark analysis. We examined test fires from 10 pistol slides with consecutively manufactured breech faces. A total of nine test fires from each pistol slide, for a total of 90 test fired cartridge cases, were compared using confocal microscopy combined with three-dimensional cross-correlation analysis algorithms. A total of 8010 comparisons were performed (720 matches and 7290 nonmatches). The average score for matches was 0.82 with a standard deviation of 0.06. The average score for nonmatches was 0.20 with a standard deviation of 0.03. Additionally, subclass toolmarks were observed on the breech faces, but the presence of subclass was not detected in the correlation analysis. There was no overlap of scores between matching and nonmatching test fires. This provides objective data that support the AFTE (Association of Firearms and Tool Mark Examiners) theory of identification.     

Investigation of Ballistic Evidence through an Automatic Image Analysis and Identification System

Automated firearms identification (AFI) systems contribute to shedding light on criminal events by comparison between different pieces of evidence on cartridge cases and bullets and by matching similar ones that were fired from the same firearm. Ballistic evidence can be rapidly analyzed and classified by means of an automatic image analysis and identification system. In addition, it can be used to narrow the range of possible matching evidence. In this study conducted on the cartridges ejected from the examined pistol, three imaging areas, namely the firing pin impression, capsule traces, and the intersection of these traces, were compared automatically using the image analysis and identification system through the correlation ranking method to determine the numeric values that indicate the significance of the similarities. These numerical features that signify the similarities and differences between pistol makes and models can be used in groupings to make a distinction between makes and models of pistols.     

跳弹创形态学的实验研究

目的 探讨跳弹创形成的条件,研究跳弹在体内弹道学特点及致伤能力,建立跳弹创的诊断依据。方法选用国产54式手枪及56式半自动步枪,配用51式手枪弹及56式步枪弹以水磨石板为反跳靶体,射击约克夏种猪4头,复制出跳弹创模型12例。观察射入口、创道及着弹点特征。结果 跳弹的形成受靶体性状、弹头形态和速度、入射角与反跳角等条件因素的影响;在相同条件下高初速尖型弹头的反跳角<低初速圆型弹头;创道无明显瞬时空腔效应;根据实验结果建立了6项诊断依据。结论 正确诊断跳弹创对射击方向和距离、重建弹道、分析枪击目的、评估损伤程度有实用价值。     

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。     

Reference ballistic imaging database performance

Ballistic imaging databases allow law enforcement to link recovered cartridge cases to other crime scenes and to firearms. The success of these databases has led many to propose that all firearms in circulation be entered into a reference ballistic image database (RBID). To assess the performance of an RBID, we fired 4200 cartridge cases from 600 9 mm Para Sig Sauer model P226 series pistols. Each pistol fired two Remington cartridges, one of which was imaged in the RBID, and five additional cartridges, consisting of Federal, Speer, Winchester, Wolf, and CCI brands. Randomly selected samples from the second series of Remington cartridge cases and from the five additional brands were then correlated against the RBID. Of the 32 cartridges of the same make correlated against the RBID, 72% ranked in the top 10 positions. Likewise, of the 160 cartridges of the five different brands correlated against the database, 21% ranked in the top 10 positions. Generally, the ranking position increased as the size of the RBID increased. We obtained similar results when we expanded the RBID to include firearms with the same class characteristics for breech face marks, firing pin impressions, and extractor marks. The results of our six queries against the RBID indicate that a reference ballistics image database of new guns is currently fraught with too many difficulties to be an effective and efficient law enforcement tool.     

Reference ballistic imaging database performance

Ballistic imaging databases allow law enforcement to link recovered cartridge cases to other crime scenes and to firearms. The success of these databases has led many to propose that all firearms in circulation be entered into a reference ballistic image database (RBID). To assess the performance of an RBID, we fired 4200 cartridge cases from 600 9mm Para Sig Sauer model P226 series pistols. Each pistol fired two Remington cartridges, one of which was imaged in the RBID, and five additional cartridges, consisting of Federal, Speer, Winchester, Wolf, and CCI brands. Randomly selected samples from the second series of Remington cartridge cases and from the five additional brands were then correlated against the RBID. Of the 32 cartridges of the same make correlated against the RBID, 72% ranked in the top 10 positions. Likewise, of the 160 cartridges of the five different brands correlated against the database, 21% ranked in the top 10 positions. Generally, the ranking position increased as the size of the RBID increased. We obtained similar results when we expanded the RBID to include firearms with the same class characteristics for breech face marks, firing pin impressions, and extractor marks. The results of our six queries against the RBID indicate that a reference ballistics image database of new guns is currently fraught with too many difficulties to be an effective and efficient law enforcement tool.     

Comparison of the Class and Individual Characteristics of Turkish 7.65 mm Browning/.32 Automatic Caliber Self‐Loading Pistols with Consecutive Serial Numbers

Abstract: Firearms identification is based on the fundamental principle that it is impossible to manufacture two identical items at the microscopic level. As firearm manufacturing technologies and quality assurance are improving, it is necessary to continually challenge this principle. In this study, two different makes of 7.65 mm Browning/.32 Automatic caliber self‐loading pistols of Turkish manufacture were selected and examined. Ten pistols with consecutive serial numbers were examined and each fired 10 times. The fired cartridge cases were recovered for comparison purposes. It was found that for each make of pistol, the individual characteristics within the firing pin impression, ejector, and breech face marks of all 10 pistols were found to be significantly different.     

七七式手枪推弹突笋痕与发射顺序的研究

目的研究七七式手枪射击弹壳的排序,找出射击顺序之间的关系。方法通过已知顺序的实弹射击取样,用显微镜观察弹壳上连续射击过程中形成的推弹突笋痕迹,经过统计、归纳,从中发现与射击顺序之间的关系。结果根据弹壳底面的推弹突笋痕迹变化规律判断出七七式手枪发射子弹的顺序。结论为指导涉枪案件的检验鉴定提供依据。     

Performance Evaluation of a Registered Ballistic Database Using the Evofinder® System

Firearms for police in China are registered along with their fired bullets and cartridge cases. A Registered Ballistic Database (RBD) of 1000 Norinco QSZ‐92 pistols with registered ammunition was established and was evaluated through the Evofinder® system. In this research, 1000 bullets and 1000 cartridge cases were randomly selected and correlated against an RBD of 2996 bullets and 2999 cartridge cases. Examiners found that successful identifications all ranked 1st, supported with land (100%), groove (97%) engraved areas, and primary marks (85.6%) for bullets, and firing pin impressions (99.8%), and breech face marks (99.9%) for cartridge cases. Two known matches (KM) for the same pistol rank in the top two (100%). The distribution of similarity scores varies from marks; however, the Evofinder® system could still effectively distinguish known matches from known nonmatches (KNM) for either bullets or cartridge cases. This study demonstrates the efficiency of the RBD.     

Identification of the murder weapon by intricate patterned injury measurements

Critical studies of an intricate blunt force injury pattern in a brutal homicide led to the identification of the murder weapon. A 50-year-old male was bludgeoned to death in his apartment during a robbery allegedly engineered by his daughter. Careful measurements and overlay construction of the wounds relative to the magazine catch, lanyard ring, magazine chamber, and butt of a 32-caliber Eistegui Hermanos fibar (Espa?a) automatic pistol led to the conclusion that either the alleged weapon or one identical to it caused the fatal injuries.     

Evaluation of the possibility of differentiation between various types of ammunition by means of GSR examination with SEM-EDX method.

Gunshot residues originating from six types of pistol ammunition were studied. Six persons who normally have no contact with weapons fired three times, each person from a different pistol. Samples of gunshot residues were collected from the shooters' hands using aluminium stubs with black carbon adhesive tabs and subjected to examinations of their morphology and elemental content by means of a scanning electron microscope with an energy dispersive X-ray spectrometer in an automatic manner. In a comparative study of the samples, only primer residues were taken into account. The frequency of occurrence of particles representing a certain chemical class against the total number of detected particles was expressed as a percentage. Mutual relations between the frequencies of occurrence of the residues of particular chemical content were found to be different for most of the studied ammunition types using a non-statistical approach--and by means of non-parametric statistical methods (R-Spearman and tau-Kendall correlation coefficients), it was possible to differentiate one ammunition type from each of the other ammunition types examined. The performed examinations have revealed some differences in the frequencies of occurrence of certain chemical classes of primer residues, observed for various types of ammunition. These differences could constitute a valuable contribution to group identifications of ammunition made on the basis of physical and chemical examinations of gunshot residues.     

Once again: risk of injury caused by blank pistols

The nature and extent of the use of blank pistols in Hamburg (according to the Hamburg crime statistics about 300 to 400 such cases per year; 34 cases involving head and neck wounds from 1989 to 1999 were investigated at our institute; among these 8 suicides, no homicide) as well as patterns of injuries caused by close distance blank pistol shots were analysed. 7 of these cases are described in detail. The results of our studies corroborate the warning statements made by many criminological and medico-legal experts regarding the danger inherent in these allegedly harmless weapons. Blank cartridge pistols can, when shot from a close distance, cause most severe injuries involving penetration into body cavities and bodily organs (especially in the head and neck), and even perforation of the skull. Therefore, we call for a much stricter control of weapons of this kind.     

Mandibular fracture caused by absolute close-range gunshot with a blank cartridge fright weapon]

Bony injuries caused by starter's pistols were repeatedly observed in the form of fractures of the temporal squama and other thin osseous lamellae; in experiments rib fractures could also be produced. In the presented case a contact shot from a blank cartridge pistol caused a fracture of the lower jaw (transverse fracture with a bone fragment split off in reg. 46). The friend of the 17-year-old victim had fired a shot to the right mandibular region during an argument. In the depth of the gunshot entrance wound, which communicated with the oral cavity, intense soot deposits were found as signs of the contact shot.     

Comparison of three DNA extraction methods for three different types of fired and unfired ammunition

When handling ammunition for gun loading, epithelial cells from the hands can become adhered to the metal surface, and this trace is a potential source of DNA. This work aimed to compare the efficiency of three DNA extraction methods from fired cartridge cases from three different types of firearms: a 12-gauge shotgun, a point 40 S&W pistol, and a 7.62 mm rifle. Nine volunteers were involved in this study handling 42 pieces of ammunition overall. The unfired ammunition was handled by a known good donor, and we used this data for comparison. DNA profiling was carried out with EZ1 DNA Investigator Kit for EZ1 Advanced XL automated DNA extraction, QIAmp DNA Investigator kit for a non-automated silica-based membrane column method, and direct lysis protocol for a non-automated in-house one. Samples were collected with 0.5 × 0.5 cm pieces of FTA filter paper moistened with distilled water. Quantiplex Pro RGQ kit and Fusion Powerplex 6C were used for genotyping samples. QIAmp DNA Investigator method resulted in the best number of alleles recovered for both conditions tested, both unfired and fired ammunitions: 77 % vs. 19.3 %, followed by the automated extraction (28.6 % vs. 4.3 %) and lysis protocol (0 % vs. 3.9 %). Degradation data from fired cartridge cases were 27 % for column method, 50 % for lysis protocol, and 87 % for EZ1 kit. Kruskal-Wallis test for mean DNA concentration from these samples returned p < 0.05, and Dunn’s multiple comparison test indicated a significant difference between calibers 0.40 S&W and 12-gauge shotgun from lyses protocol method. We did not detect any other significant differences on the test. The 12-gauge shotgun cartridge cases resulted in a high number of alleles overall (56.8 %). The numerous steps for DNA extraction and purification in the column method may explain its better performance. Although the results obtained indicate that all methods be used for DNA extraction from this type of evidence, the silica-based membrane column method appears to be more efficient.     

Classification of firing pin impressions using HOG-SVM

Crimes, such as robbery and murder, often involve firearms. In order to assist with the investigation into the crime, firearm examiners are asked to determine whether cartridge cases found at a crime scene had been fired from a suspect's firearm. This examination is based on a comparison of the marks left on the surfaces of cartridge cases. Firing pin impressions can be one of the most commonly used of these marks. In this study, a total of nine Ruger model 10/22 semiautomatic rifles were used. Fifty cartridges were fired from each rifle. The cartridge cases were collected, and each firing pin impression was then cast and photographed using a comparison microscope. In this paper, we will describe how one may use a computer vision algorithm, the Histogram of Orientated Gradient (HOG), and a machine learning method, Support Vector Machines (SVMs), to classify images of firing pin impressions. Our method achieved a reasonably high accuracy at 93%. This can be used to associate a firearm with a cartridge case recovered from a scene. We also compared our method with other feature extraction algorithms. The comparison results showed that the HOG-SVM method had the highest performance in this classification task.     

Accuracy of comparison decisions by forensic firearms examiners

This black box study assessed the performance of forensic firearms examiners in the United States. It involved three different types of firearms and 173 volunteers who performed a total of 8640 comparisons of both bullets and cartridge cases. The overall false-positive error rate was estimated as 0.656% and 0.933% for bullets and cartridge cases, respectively, while the rate of false negatives was estimated as 2.87% and 1.87% for bullets and cartridge cases, respectively. The majority of errors were made by a limited number of examiners. Because chi-square tests of independence strongly suggest that error probabilities are not the same for each examiner, these are maximum-likelihood estimates based on the beta-binomial probability model and do not depend on an assumption of equal examiner-specific error rates. Corresponding 95% confidence intervals are (0.305%, 1.42%) and (0.548%, 1.57%) for false positives for bullets and cartridge cases, respectively, and (1.89%, 4.26%) and (1.16%, 2.99%) for false negatives for bullets and cartridge cases, respectively. The results of this study are consistent with prior studies, despite its comprehensive design and challenging specimens.     

Effects of kinetic energy and firearm-to-target distance on fracture behavior in flat bones

This research implements a fractographic approach to investigate the relationships between kinetic energy, firearm-to-target distance, and various aspects of fracture behavior in gunshot trauma. Gunshot experiments were performed on pig scapulae (n = 30) using three firearms generating different muzzle (initial) kinetic energies, including a 0.32 pistol (103 J), 0.40 pistol (492 J), and 0.308 rifle (2275 J). Specimens were shot from two distances: 10 cm (n = 15) and 110 cm (n = 15). Features evaluated in fractographic analysis such as cone cracks, radiating cracks, crack branching points, and circumferential cracks could be easily identified and measured in flat bones and allowed for statistical comparison of crack propagation behavior under different impact conditions. Higher-energy bullets produced more radiating cracks, more crack branching points, and longer fracture lengths than lower-energy bullets. Distance had no significant effect on fracture morphology at the distances tested. That quantitative measures of crack propagation varied with energy affirms that kinetic energy transfer is important in determining the nature and extent of fracture in gunshot wounds and suggests it may be possible to infer relatively high- versus relatively low-energy transfer using these features. Ranges obtained with the three firearms exhibited considerable overlap, however, indicating that other variables such as bullet caliber, mass, and construction influence the efficiency of energy transfer from bullet to bone. Therefore, fracture morphology cannot be used to identify a specific firearm or to directly reconstruct the muzzle (initial) kinetic energy in forensic cases.