Semiautomatic Pistols Research Articles

Evaluation of GLOCK 9 mm Firing Pin Aperture Shear Mark Individuality Based on 3,156 Different Pistols (Manufactured Over a 30 Year Period in Two Countries) Using Additional Pattern Matching and IBIS Pattern Recognition

Over a period of 30 years, a number of fired GLOCK cartridge cases have been evaluated. A total of 3156 GLOCK firearms were used to generate a sample of the same size. Our research hypothesis was that no cartridge cases fired from different 9 mm semiautomatic GLOCK pistols would be mistaken as coming from the same gun (a false match). Using optical comparison microscopy, two separate experiments were carried out to test this hypothesis. A subsample of 617 test-fired cartridge cases were subjected to algorithmic comparison by the Integrated Ballistics Identification System (IBIS). The second experiment subjected the full set of 3,156 cases to manual comparisons using traditional pattern matching. None of the cartridge cases were “matched” by either of these two experiments. Using these empirical findings, an established conservative Bayesian probability model was used to estimate the chance that a 9 mm cartridge case, fired from a GLOCK, could be mistaken as coming from the same firearm when in fact it did not (i.e., the false match probability).

IMPACTS of SUPERSONIC and SUBSONIC AMMUNITION on GUNSHOT RESIDUE DISTRIBUTION

In incidents where firearms are involved, the determination of the firing distance is one of the basic steps of the analysis aimed at determining the origin of the incident with Forensic Shot Analysis studies. Shot residues consist of partially burned and unburnt powder grains, gunpowder gas, capsule residues and inorganic and organic residues. As a result of determining the presence and density of shot residues on the target, the distance from which the shot was fired can be determined. The pattern and density of shot residues exhibit a direct correlation with the specifications of firearms and ammunition. The intended use and traits of the weapon affect the properties of the ammunition. An instance of specialised ammunition is subsonic cartridges which have lower powder burn rates and amounts compared to supersonic cartridges. To ensure accurate gunshot residue analysis, gunshot residue density and pattern from reference test-fires are necessary. The key factors affecting the GSR analysis are the type of weapon and ammunition used during test-fires, which should closely match those used in the incident. Any variation in these variables can reduce the precision of the residue analysis. In the study, an independent T-test was applied to determine whether there is a significant difference between the gunshot residue density on the target during test firing of 9×19mm diameter and type Supersonic and Subsonic cartridges with semi-automatic pistols at distances of 0cm, 15cm, 30cm, 60cm and 100cm. It was determined that a significant difference existed between supersonic and subsonic cartridges in the density and patterns of gunshot residue on the target resulting from shots fired at the mentioned distances.

The wounding potential of assault rifles: analysis of the dimensions of entrance and exit wounds and comparison with conventional handguns. A multicentric study.

The appearance of agunshot wound (GSW) is greatly influenced by the velocity of the projectile, where high-velocity projectiles (HVPs) are defined as ballistic agents reaching a muzzle velocity of > 600 m/s fired from assault rifles. The aim of the study is to present and explain the differences in the dimensions of entrance and exit wounds between the most used handguns and assault rifles and to propose a predictor of HVP, i.e., the ratio of exit and entrance wounds (EX/ENR). The surface area of entrance and exit GSWs and the EX/ENR were calculated. 66perforating GSWs produced by NATO FMJ 7.62 × 52 mm and 5.56 × 42 mm fired from assault rifles were assigned to the HVP, while 64 lesions produced by conventional projectiles fired from revolvers and semi-automatic pistols were assigned to the low-velocity projectile (LVP) group. The dimensions of the exit wounds of the HVP group were significantly higher when compared to the LVP group (95% CI 0.9886-2.423, p < 0.05). The HVP group showed significantly higher values for the EX/ENR when compared to the LVP group (95% CI 2.617-7.173, p < 0.05). The evaluation of the EX/ENR can be considered an adequate tool to assess the type of weapon involved and to roughly estimate the associated wounding mechanisms, which can guide both the physician in the management and treatment of the patients affected by GSW, and the forensic pathologist in crime investigation.

“Are Canadian Street Cops Outgunned?”: The Debate over Police Handguns in the 1990s

AbstractThis article offers the first scholarly analysis of the shift from revolvers to semi-automatic handguns in Canada to contribute to our knowledge of police militarization. In the 1990s, most Canadian police handed in their venerable service revolvers and received modern semi-automatic pistols. Advocates of new weapons pointed to relatively rare but high-profile shootings of police to show the dangers of law enforcement work and the need to have better firearms. The gun industry encouraged the rearming of police through an aggressive marketing campaign emphasizing that modern police forces required more advanced weapons and the military lineage of their products. The transition to semi-automatic handguns sometimes proved controversial, as human rights advocates believed the new handguns could result in excessive use of force. Despite this concern, most police were rearmed by the beginning of the twenty-first century.

Effects of semi-automatic pistol slide pull device on law-enforcement racking process

Under life-threatening circumstances, the interaction between law enforcement officers and pistol slides during the racking and reloading process is critical to survival. Nine expert law-enforcement officers were recruited to investigate the effects of slide pull devices on application time and performance using semi-automatic pistols. Participants were asked to manually rack both standard and augmented slide pull devices and then clean three magazines. Videos and times were recorded to compare the slide types. Using a Welch’s t-test, no racking time difference between standard and augmented (p=0.9756) was found, but there is a slightly statistically significant difference in error rate (p=0.0765), with the augmented slide causing fewer errors. Additionally, seven of the nine officers preferred the augmented to the standard slide. Despite the lack of statistical significance with an α-level of.05, the biomechanical differences between slides and user preferences may indicate that slide types can augment participants’ performances to be more precise.

Forensic comparison of fired cartridge cases: Feature-extraction methods for feature-based calculation of likelihood ratios

We describe and validate a feature-based system for calculation of likelihood ratios from 3D digital images of fired cartridge cases. The system includes a database of 3D digital images of the bases of 10 cartridges fired per firearm from approximately 300 firearms of the same class (semi-automatic pistols that fire 9 mm diameter centre-fire Luger-type ammunition, and that have hemispherical firing pins and parallel breech-face marks). The images were captured using Evofinder®, an imaging system that is commonly used by operational forensic laboratories. A key component of the research reported is the comparison of different feature-extraction methods. Feature sets compared include those previously proposed in the literature, plus Zernike-moment based features. Comparisons are also made of using feature sets extracted from the firing-pin impression, from the breech-face region, and from the whole region of interest (firing-pin impression + breech-face region + flowback if present). Likelihood ratios are calculated using a statistical modelling pipeline that is standard in forensic voice comparison. Validation is conducted and results are assessed using validation procedures and validation metrics and graphics that are standard in forensic voice comparison.

A historical examination of police firearms

This study provides a historical examination of firearms in policing to understand how weapons have evolved within the American field. A search was conducted of historical newspaper databases and a small number of books and journal articles for information on the different firearms used in policing since their inception. The evidence demonstrates that US police officers have been using revolvers since the Civil War, but there were no agency standards until the late 19th century. The notion of ‘risk’ has been a consistent justification for arming police officers, including their possession of semiautomatic pistols, shotguns, and rifles.

Глушители для полуавтоматических пистолетов с подвижным стволом

Глушители для полуавтоматических пистолетов с подвижным стволом

Rearward movement of the slide in semi-automatic pistols: a factor potentially influencing the configuration of muzzle imprint marks in contact shots.

A muzzle imprint mark is a highly diagnostic finding, which indicates a contact shot. In many cases, it also provides additional information on the type of the weapon used and on the way in which it was held at the time of firing. In semi-automatic pistols, some constructional elements constituting the muzzle plane move to the rear together with the slide, which may prevent them from causing a corresponding imprint close to the bullet entrance hole. The present study comprises 30 consecutive autopsy cases of fatal contact shots to the head inflicted with semi-automatic pistols. The imprint marks accompanying the entrance wounds were compared with the muzzle ends of the respective weapons both before and after retracting the slide. It turned out that in a considerable number of cases (3 out of 30), the retractable parts were not depicted or only to a minor degree as components of the imprint mark. In order to validate the presumed correlation, experimental shots were fired to composite models using pistols in which the movable and the stationary parts forming the muzzle plane were dyed with different paints. Thus, it could be demonstrated that the muzzle imprint preferentially mirrors the front sides of the stationary parts such as the barrel end, the recoil guide, and the gun housing. Immediately after discharge, the slide and the ballooning skin of the bullet entrance site move in the same direction. The stationary parts of the weapon block the expansion of the skin bulging towards the muzzle, so that the skin gets firmly pressed against them. The dynamic interaction between the gun and the entrance region resulting in a characteristic imprint mark could be visualized by the use of a high-speed motion camera recording test shots to different composite models.

THE TRADE IN TOOLS: THE MARKET FOR ILLICIT GUNS IN HIGH‐RISK NETWORKS

AbstractIllegal guns circulating among high‐risk networks represent a threat to the security and well‐being of urban neighborhoods. Research findings reveal that illegal firearms are usually acquired through a variety of means, including theft and diversions from legitimate firearms commerce. Little is known, however, about the underground gun markets supplying the gang and drug networks responsible for a large share of gun violence in U.S. cities. In this article, we take a mixed‐methods approach, combining trace analyses of recovered handguns with ethnographic interviews of high‐risk gun users to develop new insights on the entry of guns into three criminal networks in Boston. We find that guns possessed by Boston gang members are of a different character compared with other crime guns; these guns are more likely to be older firearms originating from New Hampshire, Maine, and I‐95 southern states. The results of our qualitative research reveal that gang members and drug dealers pay inflated prices for handguns diverted by traffickers exploiting unregulated secondary market transactions, with significant premiums paid for high‐caliber semiautomatic pistols. Taken together, these findings provide an analytic portrait of the market for illicit guns among those most proximate to violence, yielding novel empirical, theoretical, and practical insights into the problem of criminal gun access.

Distortion of the temporary cavity and its influence on staining in firearm barrels.

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 12cm 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 9mm 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 9mm 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.

Long-Term Trends in the Sources of Boston Crime Guns

Analyses of firearm trace data, most collected over relatively brief periods, suggest that a noteworthy share of guns used in crime were recently diverted from legal commerce. This article analyzes a longitudinal database on firearm recoveries by the Boston Police Department between 1981 and 2015 and successfully traced handguns between 1991 and 2015. The percentage of high-capacity semiautomatic pistols among recovered handguns increased dramatically in the 1980s and 1990s. A persistent share of traced handguns were imported from licensed dealers in southern states and an increasing share first purchased at licensed dealers in New Hampshire and Maine. These analyses suggest that market disruption strategies may reduce illegal diversions of new handguns from licensed dealers and the passage of one-handgun-a-month laws may influence where criminals get their guns.

An investigation into the factors that influence toolmark identifications on ammunition discharged from semi-automatic pistols recovered from car fires

Following a shooting incident where a vehicle is used to convey the culprits to and from the scene, both the getaway car and the firearm are often deliberately burned in an attempt to destroy any forensic evidence which may be subsequently recovered. Here we investigate the factors that influence the ability to make toolmark identifications on ammunition discharged from pistols recovered from such car fires. This work was carried out by conducting a number of controlled furnace tests in conjunction with real car fire tests in which three 9mm semi-automatic pistols were burned. Comparisons between pre-burn and post burn test fired ammunition discharged from these pistols were then performed to establish if identifications were still possible. The surfaces of the furnace heated samples and car fire samples were examined following heating/burning to establish what factors had influenced their surface morphology. The primary influence on the surfaces of the furnace heated and car fire samples was the formation of oxide layers. The car fire samples were altered to a greater extent than the furnace heated samples. Identifications were still possible between pre- and post-burn discharged cartridge cases, but this was not the case for the discharged bullets. It is suggested that the reason for this is a difference between the types of firearms discharge-generated toolmarks impressed onto the base of cartridge cases compared to those striated along the surfaces of bullets. It was also found that the temperatures recorded in the front foot wells were considerably less than those recorded on top of the rear seats during the car fires. These factors should be assessed by forensic firearms examiners when performing casework involving pistols recovered from car fires.

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

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 60h 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 2ms, preceding the maximum of the temporary cavity, and the powder pocket's collapse takes 2.5 to 3ms.The size of the silicone dome increased with decreasing barrel length. Comparing semi-automatic pistols of 4in. 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.

Deaths resulting from the use of firearms by police against motor vehicles: Study of cases in Porto, Portugal

The objective of this study was to investigate the terminal ballistics of police shootings in which the bullets went through any motor vehicle structure before fatally wounding the occupants. 6 cases that occurred in Porto district between 1998 and 2013 were studied. The firearms used were 7.65 mm (n = 1) or 9 mm (n = 3) calibre semi-automatic pistols and 9 mm calibre submachine guns (n = 2); the bullets were full metal jacket type. The metal jacket of the collected projectiles was totally or partially destroyed in 3 cases. It exhibited a deformed structure in all cases. The trajectories of the bullets in the vehicles were always more or less linear, even when initial impact was at an oblique angle. The entry holes in the victims' bodies were larger or much larger in size than the calibre of the bullets. They were located, with the exception of one of the cases, in the left half of the body. The trajectories in the victims' bodies were from front to back, in one case, and from back to front in all others. Exit wounds were only found in two cases. Death occurred immediately after the victim was shot only in one case, despite a vital structure has been hit in all cases. The cases studied support the idea that the use of firearms against vehicles with the sole intention of immobilisation entails uncontrollable danger to the lives of the occupants, and especially when done by police forces not specifically trained for that purpose. Therefore, such use of firearms should be avoided.

Evaluation of GLOCK 9 mm Firing Pin Aperture Shear Mark Individuality Based On 1,632 Different Pistols by Traditional Pattern Matching and IBIS Pattern Recognition.

Over a period of 21 years, a number of fired GLOCK cartridge cases have been evaluated. A total of 1632 GLOCK firearms were used to generate a sample of the same size. Our research hypothesis was that no cartridge cases fired from different 9-mm semiautomatic GLOCK pistols would be mistaken as coming from the same gun. Using optical comparison microscopy, two separate experiments were carried out to test this hypothesis. A subsample of 617 test-fired cases were subjected to algorithmic comparison by the Integrated Ballistics Identification System (IBIS). The second experiment subjected the full set of 1632 cases to manual comparisons using traditional pattern matching. None of the cartridge cases were "matched" by either of these two experiments. Using these empirical findings, an established Bayesian probability model was used to estimate the chance that a 9-mm cartridge case, fired from a GLOCK, could be mistaken as coming from the same firearm when in fact it did not (i.e., the random match probability).

An Analysis of the Characteristics of Thoracic and Abdominal Injuries Due to Gunshot Homicides in Israel.

De-identified wound data from 197 homicidal gunshot postmortems were obtained between 2000 and 2008. Forensic ballistics data were only available for cases between 2004 and 2008. Males represent 91% of gunshot victims and were struck in the thorax/abdomen with an average of 2.3 bullets. The type of firearms involved were semi-automatic pistols in the predominant caliber 9-mm Luger and assault rifles in caliber 5.56 × 45 mm and caliber 7.62 × 39 mm Soviet, using full metal jacket bullets. The majority of shootings occurred at ranges of 1 m or greater. The most common bullet path was front to back in 66% of cases. Entry wounds occurred more often on the left side of the thorax, abdomen, and back. The most common critical organs/tissues to sustain bullet trauma in descending order were as follows: heart, lungs, liver, aorta, spleen, kidneys, and vena cava. Ribs were struck by most bullets that entered the thorax.

The examination, evaluation, and identification of 40 S&W calibre cartridge cases fired from 1079 different GLOCK semiautomatic pistols manufactured over a six-year period

One thousand and seventy-nine (1079) pairs of fired 40 S&W calibre cartridge cases were obtained from the GLOCK Firearms Manufacturing Facility in Smyrna, Georgia over a six-year period and examined as part of their quality assurance program. The test-fired pairs included several pairs that were fired from consecutively manufactured slides and distributed geographically to three states in the United States. All of the cartridge cases were microscopically examined, evaluated, and intercompared by the authors using forensic optical comparison microscopy to determine if the fired cartridge cases could be individualized to themselves and to the exclusion of the remaining cases. The examination also involved evaluating each of the fired cartridge cases for sub-class characteristics.

Psychiatrists Should Be Advocates for Gun-Control Laws

Psychiatrists Should Be Advocates for Gun-Control Laws

Patterned imprint mark due to the folded shoulder stock: A possible finding in contact shots from submachine guns

The muzzle imprint (barrel mark) is a pressure abrasion typically associated with contact shots. Apart from the contours of the actual muzzle profile, other constructional parts such as the front sight and/or the recoil spring guide of semiautomatic pistols may be imprinted next to the bullet entrance wound. In some types of submachine guns the shoulder stock can be folded forward so that its end partly encircles the muzzle. If such a weapon was in contact with the skin at the instant of discharge, a corresponding contusion mark is to be expected. The imprint configuration may point to the type of weapon and to the way in which the gun had been held when firing the shot. The paper presents the injury pattern in a 36-year-old man who committed suicide with a Scorpion SA Vz 61 submachine gun cal. 7.65 mm Browning from former Czechoslovakia.