Bullet Surface Research Articles

Divergent gunshot residues and characterization of the memory effect in a .22 caliber revolver and pistol

BackgroundThe forms and compositions of primer gunshot residue (GSR) in shooting cases have been routinely analyzed in many crime labs by scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS). Gunshot residue studies over the last 30 years have identified a contribution by residual GSR from surfaces within the firearm to GSR (the “memory effect”). In this study, we first focus on the GSR compositional differences between target, bore, and cylinder gap for a .22 caliber revolver which has received little attention in the literature. Secondly, we examine the behavior of elements involved in the residual contribution to GSR for a .22 caliber pistol.ResultsThe compositions of target, bore, and cylinder gap GSRs from a .22 caliber revolver were determined for 11 discharge series. Breech GSR compositions from a .22 caliber pistol changed in sequential discharges revealing behavior of individual primer and bullet elements. The target GSR forms from some .22 caliber ammunitions were not spherical.ConclusionsFor the revolver, GSR compositions from the target, bore, and cylinder gap are divergent. Analysis of the pistol’s breech GSRs indicated mixing with the previously deposited GSRs resulting in a sequential contribution or loss of elements and redeposition of the new composition. Aluminum did not contribute to the residual GSR. The GSR composition of a discharge and its contribution to residual GSR on the internal parts of the firearm represents a complex process which likely involves a number of variables including, but not restricted to firearm design, primer composition, pressure and temperature of the discharge gas, and bullet surface composition.

Numerical Analysis of Semi-Tangential Ogive Bullet

Abstract: The objective of the present study is to design and analyze semi-tangential ogive bullets using simulatation software such as Computer-aided design & Computational Fluid Dynamics (CFD). It is observed that been a quite steady increase in the bullet research design in the past few decades. The nose section of ballistic bullet is the most important part of the design process. Hence design optimizations are achieved by adjusting the bullet's form to improve precision and stability by reducing its drag force. CFD is the study used to verify the findings. Since provides most accurate results. It is observed that present study optimizes the behavior of the at M= 2.5. This present work shows the flow of air around the bullet surface providing pressure & velocity contours at every segment. The Various parametric studies over bullet model are drag co-efficient, ballistic coefficient and turbulence viscosity are plotted’.

Temperature Measurement of a Bullet in Flight.

This study answers a primary question concerning how the temperature changes during the flight of a bullet. To answer the question, the authors performed unique research to measure the initial temperatures of bullet surfaces and applied it to four kinds of projectiles in a series of field experiments. The technique determines the temperature changes on metallic objects in flight that reach a velocity of 300 to 900 m/s. Until now, the tests of temperature change available in the literature include virtual points that are adopted to ideal laboratory conditions using classic thermomechanical equations. The authors conducted the first study of its kind, in which is considered four projectiles in field conditions in which a metallic bullet leaves a rifle barrel after a powder deflagration. During this process, heat is partly transferred to the bullet from the initial explosion of the powder and barrel-bullet friction. In this case, the temperature determination of a bullet is complex because it concerns different points on the external surface. Thus, for the first time the authors measured the temperatures at different position on the bullet surface. Moreover, the authors showed that basic thermodynamic equations allow for the credible prediction of such behavior if the initial conditions are identified correctly. This novel identification of the initial conditions of temperature and velocity of flying bullets was not presented anywhere else up to now.

Bullet fast matching based on single point laser detection

Bullet trace detection’s main task is determining the type of bullet and the identity of the gun that fired it. In order to solve conventional bullet trace matching method problems, a bullet fast matching method based on single point laser detection is proposed. First, adaptive control of the bullet center position and cylinder axis were performed. Then, a laser displacement sensor was implemented to perform a 360° detection in order to trace rifling on the bullet surface in the circumferential direction; grayscale morphological filtering was implemented in order to de-noise detection data, and the Pearson correlation coefficient was implemented in order to perform the trace similarity matching calculation, thereby achieving a fast bullet trace matching. Moreover, the algorithm’s effectiveness was verified via practical testing data.

A Bayesian approach based on Kalman filter frameworks for bullet identification

When a bullet is fired from a barrel, random imperfections in the interior surface of the barrel imprint 3-D micro structures on the bullet surface that are seen as striations. Despite being random and non-stationary in nature, these striations are known to be consistently reproduced in a unique pattern on every bullet. This is a key idea in bullet identification. Common procedures in the field of automatic bullet identification include extraction of a feature profile from bullet image, profile smoothing and comparison of profiles using normalized cross correlation. Since the cross correlation based comparison is susceptible to high-frequency noise and nonlinear baseline drift, profile smoothing is a critical step in bullet identification. In previous work, we considered bullet images as nonlinear non-stationary processes and applied ensemble empirical mode decomposition (EEMD) as a preprocessing algorithm for smoothing and feature extraction. Using EEMD, each bullet average profile was decomposed into several scales known as intrinsic mode functions (IMFs). By choosing an appropriate range of scales, the resultant smoothed profile contained less high-frequency noise and no nonlinear baseline drift. But the procedure of choosing the proper number of IMFs to reduce the high-frequency noise effect was manual. This poses a problem in comparison of bullets whose images contained less or more noise in comparison to others because their useful information may be present in the corresponding discarded IMFs. Moreover, another problem arises when the bullet type changes. In this case manual inspection is needed once more to figure out which range of IMFs contain less high-frequency noise for this particular type of bullet. In this paper, we propose a novel combination of EEMD and Bayesian Kalman filter to solve these problems. First the bullet images are rotated using Radon transform. The rotated images are averaged column-wise to acquire averaged 1-D profiles. The nonlinear baseline drifts of averaged profiles are removed using EEMD algorithm. The profiles are then processed by a Kalman filter that is designed to automatically and optimally reduce the effect of high-frequency noise. Using Expectation Maximization (EM) technique, for each averaged profile, the parameters of Kalman filter are reconfigured to optimally suppress the high-frequency noise in each averaged profile. This work is the first effort that practically implements the Kalman filter for optimal denoising of firearm image profiles. In addition, we believe that Euclidean distance metric can help the normalized cross-correlation based comparison. Therefore, in this paper, we propose a comparison metric that is invariant to start and endpoints of firearm image profiles. This metric combines the prized properties of both Euclidean and normalized cross-correlation metrics in order to improve identification results. The proposed algorithm was evaluated on a database containing 180 2-D gray-scale images acquired from bullets fired from different AK-47 assault rifles. Although the proposed method needs more calculations in comparison to conventional methods, the experiments showed that it attained better results compared with the conventional methods and the previous method based on EMD in the field of automatic bullet identification.

Numerical investigation of hybrid blend design target bullets

In the past few decades, researchers are involved in the studies of high-energy penetrator geometry and also the materials used for causing brutal damages on enemy targets. The highly focused area in this field is the shape of the nose and penetration angle of the penetrator. Hybrid blend design target bullets is one among the best aerodynamic design as it is having two different shapes within the nose. The design of these bullets plays an influential role in terms of aerodynamic characteristics and its dynamic performance capability on hitting the targets. Objective of this research is to perform a comparative analysis of 3 different geometrically varied shapes of these bullets by numerical simulation using CFD, based on its performance characteristics such as aerodynamic co-efficients, shock wave existence, Turbulent dissipation rate and normal drag force on the bullet surface.

A correlation based bullet identification method using empirical mode decomposition

The striations on bullet surface are 3D micro structures formed when a bullet is forcing its way out of barrel. Each barrel leaves individual striation patterns on bullets. Hence, the striation information of bullets is helpful for firearm identification. Common automatic identification methods process these images using linear time invariant (LTI) filters based on correlation. These methods do not consider the sensitivity of correlation based comparisons to nonlinear baseline drifts. The striations are undeniably random unique micro structures caused by random non-model-based imperfections in the tools used in rifling process, therefore any characteristic profile that is extracted from a bullet image is statistically non-stationary. Due to limitations of LTI filters, using them in smoothing bullet images and profiles may cause information loss and impact the process of identification. To address these problems, in this article, we consider bullet images as nonlinear non-stationary processes and propose a novel method which uses ensemble empirical mode decomposition (EEMD) as a preprocessing algorithm for smoothing and feature extraction. The features extracted by EEMD algorithm not only contain less noise, but also have no nonlinear baseline drifts. These improvements help the correlation based comparison methods to perform more robustly and efficiently. The experiments showed that our proposed method attained better results compared with two common methods in the field of automatic bullet identification.

Analysis of morphology and microstructure of B4C/2024Al composites after 7.62 mm ballistic impact

The effects of ballistic impact on morphology and microstructure of B4C/2024Al composites were studied. B4C/2024Al composites with 55% volume fraction of B4C particles were prepared by pressure infiltration method, and the experimental test of ballistic performance of composites was carried out by 7.62mm armor piercing projectiles. The obvious upsetting of bullet and furrows on bullet tip are generated after bullet impact. Moreover, bared B4C particle distributes uniformly on the bullet surface, indicating that the composites target plays roles of passivation and abrasion on bullet. The protection coefficient of B4C/2024Al composites shows trends of falling, then an upward trend, at last keeping constant as the increasing thicknesses of targets, and could reach up to 2.8. For the composites target with semi-infinite thickness, three kinds of failure morphology are presented at the bullet crater: caving, erosion and melted areas, spreading successively as the increasing depth, which indicates that the interaction between bullets and targets is different at different stage of bullet penetration. Interestingly, the interface bonding of composites keeps well after bullet impact; moreover, no interface de-bonding was observed. High density of dislocation is generated in Al matrix around the interfaces, meanwhile, dislocations and micro-cracks were found in some B4C particles.

薄鋼板の跳弾痕を用いた発射弾丸，弾道の推定に関する研究

In order to estimate type and trajectory of the fired bullet from the analysis of the ricochet mark, we carried out the gunfire test against the inclined target. 1.2 mm thin steel plates were used as intermediate targets in this study. The following are types of cartridges which were used: 25 AUTO., 32 AUTO., 7.62 mm Tokarev, 380 AUTO., 38 SPL. (FMC), 38 SPL. (LRN), 9 mm Luger and 45 AUTO.. The target was put in a wooden frame. The angle of incidence was changed by rotating the wooden frame. We could classify the deformation morphology on the thin steel plate into 4 patterns: Ricochet mark without the crack (Type 1), Ricochet mark with the small crack (Type 2), Ricochet mark with the large crack (Type 3), Penetration (Type 4). Metal from the bullet surface was left on the surface of the target. It was thought that the crack in the edge of the ricochet mark (Type 2 or 3) was caused by the friction arising from the rifling rotation of the fired bullet. The length of the ricochet mark in the longitudinal direction L increases with increase of the kinetic energy of the bullet E. The value of L was relative to the kinetic energy resolved into the horizontal component of the velocity Ecos2θi (θi: the angle of incidence). Except for 380 AUTO. and 38 SPL., the value of L was almost independent of E and Ecos2θi respectively. The ratio of the angle of ricochet θr to the angle of incidence θi was around 1 to 2. Therefore, caliber and type of a fired bullet and the trajectory can be determined from the analysis of the ricochet mark and the contour when the bullet is fired into a 1.2 mm thin steel plate.

Interaction of bullets with intermediate targets: Material transfer and damage

In complex shooting incidents, it is not always clear which bullet hit or eventually killed the victim and who fired it. The examination of traces of foreign material embedded in or adhered to bullets provides critical information in the trajectory reconstruction of spent bullets. Such a reconstruction can have considerable legal implications because it can prove that it was not someone's intention to kill. However, the microtraces that remain on spent bullets are often ignored.Microtraces on bullets, around bullet-holes and on ricochet marks were investigated using SEM/EDX for two different types of bullets: a relatively hard, full metal jacket (FMJ) bullet and a relatively soft, lead round-nose (LRN) bullet. A total of 179 bullets were fired into intermediate targets, sheets of 5 different materials (MDF, greenboard, gypsum fibreboard, glass and steel), at approximate incident angles of 90°, 10° and 5°. Of the 144 bullets fired at incident angles of 90°, 130 bullets perforated one of the materials, and 14 bullets perforated two of the materials. The 35 bullets fired at incident angles of 10° and 5° ricocheted off the intermediate targets, producing ricochet marks.In the majority of cases, traces from the target materials were found on the bullet, both after perforation and ricochet. The only exceptions were (1) the perforation of 9-mm sheets of MDF by FMJ bullets and (2) ricochet off glass when the glass did not break. Steel targets transfer small, but still detectable traces of iron to the bullet. The order in which targets are hit was reflected in the traces found on the bullets, i.e., materials from a secondary target were deposited on top of deposits from the primary target. This result implies that it is possible to determine the order of impact from the stratification of the material analysed.Traces from the bullets were found around all the bullet holes. Wipe-off from lead bullets is sometimes visible by the naked eye. Ricocheting bullets produce remarkable traces on glass. The combination of sliding and flattening action leaves a trace of the bullet's surface material in the form of tiny droplets and other evidence of liquid formation. In general, softer LRN bullets are more susceptible to the transfer of material than harder FMJ bullets. For perforation, trace materials are preferentially deposited in a ring-shaped area around the (flattened or unflattened) nose of the bullet.

Reconocimiento de texturas en imágenes de proyectiles: Un aporte a la identificación automática de armas

<span>Debido al contacto entre el interior del cañón y el proyectil durante el disparo de un arma de fuego, quedan impresas marcas sobre la superficie del proyectil. Estas marcas son características de cada tipo de arma, y más aún, pueden ser interpretadas como su "huella digital". Tradicionalmente, la identificación de armas con base en el cotejo o comparación de proyectiles, realizadas por los peritos en balística, es una actividad difícil que consume mucho tiempo. La actividad consiste en observar con un macroscopio de comparación, dos proyectiles: el patrón y el incriminado. El objetivo es hallar similitudes entre las marcas que presentan los dos, y determinar si provienen o no de la misma arma. La tarea de identificación demanda el uso de computadoras debido a la cantidad de casos judiciales que implican armas de fuego. En este trabajo se presenta un método para obtener una representación bidimensional de las regiones de interés en las superficies de los proyectiles percutidos, procedimiento que en este trabajo, será llamado "desenvolver" la superficie; después, se usa un método para dotar de características cuantitativas dichas imágenes; por último, el soporte estadístico para mostrar las diferencias entre clases de armas incluidas en el experimento.</span>

DNA analysis of biological material on perforating bullets and crime scene reconstruction

DNA analysis of biological material present on a bullet surface may be an important tool for the reconstruction of a crime scene. In shooting incidents when there is more than one gunshot or victim or when the crime scene has been changed, the presence of DNA on the implicated bullet may determine that it hit the victim. The comparison of this bullet and the firearm(s) involved may identify the gun from which the bullet was fired and help to define the shooter. We report two cases of homicide by firearms in which biological material was recovered by swabbing the bullets. DNA was extracted and PCR typing of STR was carried out using the AmpFLSTR ® Identifiler (Applied Biosystems). In both cases we obtained genetic profiles from different regions on the surfaces of the two projectiles. In the two situations, DNA typing played a decisive role in the reconstruction of the crime scenes.

Mathematical Model for Estimating Perforation Penetration Depth

This article presents a simplified mathematical model based on the energy-work method to estimate the penetration depth in well perforation. The model uses casing and formation properties in the estimation. It uses the initial speed of the bullet and the failure strengths of the materials resisting penetration as model input. An automated computer program was developed to compute the penetration depth in terms of various field parameters. It was found that bullet penetration increases with increasing jetting velocity and decreasing effective bullet surface area, and that the use of explosive-type HMX1 yields higher penetration depth for the same bore size. The results also showed that the productivity ratio becomes much higher for larger borehole diameters and higher explosive speeds. Overall, the study showed that the model can be used to design for optimum penetration depths leading to an optimum productivity ratio.

Automated bullet-identification system based on surface topography techniques

Every firearm has individual characteristics that are as unique to it as fingerprints are to human beings. When a firearm is fired, it transfers these characteristics – in the form of microscopic scratches and dents – to the fired bullets and cartridge casings. The rifling of the barrel of the firearm marks the bullets travelling through it, and the firearm's breech mechanism marks the ammunition's cartridge casing. Characterising these marks is the critical element in identifying firearms. Traditionally the comparison of ballistic evidence has been a tedious and time-consuming process requiring highly skilled examiners. In the past decade, engineers have created automated ballistics identification systems that meld traditional comparison microscopes with digital cameras, computers, huge databases, and image analysis techniques. This kind of system can help investigators to link crimes by automatically finding similarities among images of bullet but suffering significant drawbacks and minimal matching. More recently, approaches based on 3D digital representations of evidence surface topography have started to appear, both in research and industrial products. Potentially the introduction of 3D surface topography measurement can overcome the limitations of digital imaging systems by making the bullet surface measurement reproducible and reliable. A 3D quantitative approach for bullet identification is proposed in this paper. In this system the surface topography of the whole bullet can be acquired for analysis and identification. Primary researches have been done by applying advanced surface topography techniques for bullet marks’ characteristics extraction. A variety of 2D and 3D visualization graphics have also been provided to help firearm examiners to make final decisions.

Development of a 3D-based Automated Firearms Evidence Comparison System

Since the early 1990's, the idea of automated systems for the comparison of microscopic firearms evidence has received considerable attention. The main objective of such systems is to enable the analysis of large amounts of evidence, therefore, transforming the comparison of firearms evidence from an evidence verification tool into a crime-fighting tool. Two such systems have been widely used in United States forensic laboratories: namely, the Integrated Ballistics Identification System (IBIS) (1) and DRUGFIRE (2). Both IBIS and DRUGFIRE have in common the fact that their characterization of a specimen is based on a two-dimensional (2D) representation of the specimen's surface. Although these systems have provided satisfactory results in the identification of cartridge cases, their performance in the identification of bullets has not yet met firearms examiner's expectations. This project was motivated by the premise that a better characterizations of the bullet's surface should translate into better performance of automated identification systems. A three-dimensional (3D) characterization of the bullet's surface is proposed as an alternative to a 2D characterization. This paper discusses the development and preliminary results obtained with SciClops, an automated microscopic comparison system based on the use of a 3D characterization of a bullet's surface.

Trajectory reconstruction from trace evidence on spent bullets. I. Deposits from intermediate targets.

Contact of a fired bullet with an intermediate target of sufficient resistance commonly causes the bullet to ricochet, fragment or perforate together with a deviation in trajectory. The transfer of intermediate target material to bullets and subsequent detection on the bullet surface after recovery from a bullet collector, were examined using a scanning electron microscope and an energy-dispersive X-ray spectrometer (SEM/EDS). A total of 76 gunshots (9 mm Luger FMJ RN bullets) were fired at various intermediate targets and at combinations of intermediate targets and tissue located in line. Elements already present on unfired bullets and elements from the bullet collector, the jacket, the charge and primer could be consistently detected as a "background". Abundant deposits of "fragile" (brittle) materials such as concrete, flat glass, asphalt and gypsum board could be visualised on every bullet by SEM. The transfer dynamics involved a direct imprint of target material on the bullet surface and thus preferential locations at the tip but also indirect deposition over the entire surface ("powder effect"). X-ray microanalysis demonstrated matching spectra of the elemental composition of these deposits and of the targets contacted. After perforation of "ductile" (flexible) materials such as wood and car body parts, the deposits on the bullets did not show characteristic spectra. If multi-layered car metal targets were hit, few and uncharacteristic fragments were scattered over the bullet surface and titanium indicative of paint-work could be determined on only a minority of bullets. The elemental composition of wood itself was heterogeneous but the fibrous morphology of the deposits was typical. The SEM/EDS findings in gunshots including subsequent perforation of tissue were similar. In particular, the trace evidence primarily transferred to the bullets was not eliminated by secondary contact and the determination of the fragile target materials was not affected. So when a person is killed or injured by a gunshot, the presence of a ricochet and the target material can be determined. This possibility needs to be considered before an evidential bullet is cleaned or contaminated.

Cosmic bullets as particle accelerators and radio sources

We have simulated in two dimensions the dynamical evolution of dense gas clouds(`cosmic bullets') moving supersonically through a uniform low-density medium. The diffusive shock acceleration of relativistic protons (cosmic rays) and their dynamical feedback on the background flow are included by the two-fluid model for this process. The acceleration of relativistic electrons is approximated by a test-particle model, and a passive magnetic field is followed by a simple advection scheme. Strong bow shocks, with Mach numbers similar to that of a bullet's motion, are the most important particle accelerators in the flow, while tail shocks and shocks inside the bullets do not play generally significant roles in this regard. For our simulation parameters, approximately greater than 10% of the initial bullet kinetic energy is converted to a combination of internal energy of gas and cosmic-ray protons by the time the bullets begin to be disrupted. Characteristically, the cosmic rays gain several percent of the available kinetic energy. Bullet destruction on timescales only a little larger than the ram pressure bullet crushing time begins in response to Kelvin-Helmholtz and especially to Rayleigh-Taylor instabilities along the forward bullet surface. For dense bullets this happens before the bullet is stopped by ram pressure. According to our simple model for synchrotron emission from relativistic electrons accelerated and transported within the flows, that emission increases rapidly as the bullet begins to fragment, when it is strongly dominated by field enhancement in sheared flows. Synchrotron emission from the acceleration region within the bow shock is, by contrast, much weaker.

A note on assessability of firing distance from gunshot residues

The quantitatively measurable evidence on a target (e.g. cloth, skin, etc.) due to bullet impact is the gunshot residue (GSR) deposited around the bullet hole and it is the only material available for extracting any quantitative information about the gun discharge from an examination of the target. At close ranges, the gaseous cloud of GSR particles is directly transported onto the target producing a radial distribution of GSR upto a few centimetres around the bullet hole. Some GSR particles are also captured on the bullet surface and transferred to the target through bullet contact during its penetration. Such bullet-carried GSR is deposited on the target at all ranges, but just around the hole margin. GSR deposits on targets resulting from the above two transfer modes can be distinguished and both processes have been investigated to evaluate the infuence of firing distance on the respective GSR deposits on targets. Two different methodologies have been proposed for close and long range estimations with the aid of GSR measurement. The proposed models are found to give encouraging results when tested against available experimental data.

Distribution of textile fibers in the path of a bullet

Twenty-one blocks consisting of 20% gelatin were fired at using firearms of the long rifle caliber .22 and .357 Magnum. The frontal area of these blocks was prepared with textile coverings marked with technetium 99m. Two gunshot series of each type were fired at summer, interseasonal, and winter clothing, using different ammunition. The radioactivity of the bombarded blocks was measured by single photon emission computed tomography (SPECT). The results of these gun shot series were presented graphically and compared. Initially (at 2 cm depth), high radioactivity is always detected, which among other things is caused by the defilement of the bullet's surface when shot through the textile covering marked by technetium. The higher radioactivity in the middle and deeper block areas is the result of fiber infiltration. Accordingly, there are greater fiber accumulations in the middle and deeper areas of the path of the bullet. This is the case mainly in thinner clothing (summer). Heavier clothing (autumn, winter) presents a greater obstacle for bullets with greater impact as well. Here, only projectiles having a lesser tendency to deform, as well as a high impact, transport a considerable proportion of textile fibers into the deeper parts of the blocks.

Identification of Bullet Holes by Residue Transfer

Abstract Antimony and copper residues deposited on the bullet surface after explosion of a pistol cartridge were measured by neutron activation analysis. The amount of residue wiped from the bullet surface upon passage through various target materials was determined. Correlations were found between the residue deposited on the target material and the bullet jacketing, caliber, and configuration