Estimating Projectile Perpendicular Impact Velocity on Metal Sheet Targets from the Shape of the Target Hole

Abstract:  The correlation between bullet hole shapes in metal and projectile impact velocity was examined. A series of shots were fired from an M-16A1 assault rifle of 5.56 mm caliber toward a 1-mm thick metal target. All shots were fired at a perpendicular angle to the metal sheets, and the velocity was measured just before the projectile hit the target. Velocities ranged between 400 and 900 m/sec. From the replica of the shooting hole, a perpendicular plane was created, showing the symmetrical properties of the hole. The best mathematical equation describing the shape of the entrance hole was the exponential function in the form:
The empirical equation of the hole defined using the regression method is:
This equation describes the general shape of shooting holes created by velocities ranging from 440 to 750 m/sec. From this equation, one can estimate the bullet velocity when it hits the target.     

The Accuracy and Repeatability of Reconstructing Single Bullet Impacts Using the 2D Ellipse Method

When a bullet punctures a surface, it leaves behind a bullet impact, which can be analyzed in order to determine the origin and trajectory path from which a bullet was discharged using many different scientific methods to reconstruct a shooting scene. The purpose of the research was to test the accuracy and repeatability of reconstructing the impact angle of single bullet impacts using the ellipse method. The research was conducted by firing various calibers of ammunition into drywall panels positioned at varying angles of incidence from 88° until ricochet occurred. This was done in order to determine which caliber type and angle of incidence are most accurate and precise for reconstructing a shooting scene. The study examined four caliber types fired into drywall panels, with 5 repeated shots for each of the 11 angles of incidence (n = 220). Furthermore, 31 participants partook in the study to estimate a bullet impact angle of incidence utilizing the ellipse method. The results show that the best performance (accuracy and repeatability) is seen with the measurements of the 0.45 caliber ammunition. When angle of incidences is low (<64°), the performance (accuracy and repeatability) was seen to be better in all caliber ammunitions. Overall, the data provided for single bullet impacts deposited in drywall show that the ellipse method is useful in providing measurements for most crime scene reconstruction purposes and has also demonstrated that results vary depending on the type of ammunition, firearm, and angle of incidence being examined.     

Shooting distance estimation for shots fired by a shotgun loaded with buckshot cartridges

The present study was carried out to clarify the problem of shooting distance estimation, by studying shots fired with buckshot ammunition in 12 gauge shotgun.For this purpose, the pattern diameter (PD) and the distances between buckshot (DBB) within the pattern were evaluated.Experimental shots were carried out with three differently choked barrels: full, half and cylinder; Winchester-Western OOB and OB buckshot ammunition were used.The results show that the estimation of shooting distance, based on the present parameters, is scarcely reliable especially when this estimation must be calculated on the basis of only a few wound holes on which measurements are made.     

A versatile technique for the investigation of gunshot residue patterns on fabrics and other surfaces: m-XRF

With heavy-metal-free ammunitions becoming more and more popular, it is necessary to find methods to visualize patterns of those elements in gunshot residues (GSRs) that are not accessible by chemographic coloring tests. The recently introduced millimeter-X-ray fluorescence analysis (m-XRF) spectrometer Spectro Midex M offers an easy way to record mappings of GSRs containing such elements in order to determine shooting distances as well as the general composition of these particles. A motorized stage enables samples of a maximum size of 20 x 20 cm to be investigated, like fabric, clothes, adhesive tapes (Filmolux films), and polyvinylalcohol gloves of shooter's hands. Human tissues can be measured using a Peltier-cooled specimen holder that is mounted onto the stage. As the spot size of the exiting X-rays lies in the millimeter range, which is adequate for the assessment of the residue patterns for shooting distance determination, a significant reduction in measurement time is achieved compared with mu-XRF methods. Test shots with heavy-metal-free ammunitions were performed on different target materials, like pork skin and fabric, and the elemental distributions of Ti, K, and Ga were determined. In order to show the capability of the spectrometer for conventional lead ammunitions as well, a shot series of 5-100 cm shooting distance and an adhesive tape of a shooter's hand were investigated analogously. A comparison of several methods applied in GSR investigation shows the advantages of the m-XRF method.     

Expert reconstruction of the true circumstances of the shooting of the Emperor Nikolai II, members of his family, and those who accompanied them into exile at Ekaterinburg

Analysis of the materials of the criminal case, historical, archive, and forensic medical documents permitted for the first time to reconstruct the circumstances of the shooting of Emperor Nikolai II, members of the royal family, and those who chose to accompany them into exile in the house of the engineer N.N. Ipatiev, Ekaterinburg, on the night of 16-17th July (Grigorian calendar) 1918. The results of the study allowed the true picture of the assassination to be reconstructed including the mutual positions of the victims and the executors in the semi-basement room No 2, the total number of participants, the number and direction of shots, the types of the weapons used, and the sequence of actions of each person involved in the event. It was shown, that in the beginning most shots had been fired at the emperor and tsarevich Alexei.     

The effects of certain intermediary target materials and their proximity to ballistic gelatin on jacketed hollow point bullet expansion

Expanding bullets are preferred by law enforcement because of their wounding potential and ability to avoid over-penetration which could result in unintended targets being struck by bullets that perforate their intended targets. Expansion failure for jacketed hollow point (JHP) bullets is commonly attributed to several causes including damage to the bullet's cavity, velocity loss, bullet destabilization and materials from intermediate targets filling the bullet's cavity which can cause expansion failure when the bullet subsequently impacts a soft, fluid-based target such as human tissue or ballistic gelatin. In this study, JHP bullets were fired into ballistic gelatin after passing through selected intermediate targets representing items common to shooting incidents. Velocity loss and bullet destabilization were not factors that contributed to the JHP bullets that experienced expansion failure; however, materials obstructing the bullets' cavities and damage to the bullets' cavities were considered causes for some of the JHP bullet expansion failures. It was determined through this research that most of the target materials caused JHP bullet expansion failure when shored against the ballistic gelatin, but when placed at distances of 7 ft. from the ballistic gelatin, bullets fired through the same target materials did expand. This original and unique study produced findings that are of significant value to shooting incident reconstruction experts and other forensic professionals as shooting incidents can call into question a victim's proximity to a wall or door when a bullet(s) perforated such a target material.     

Injury potential of soft-air pistols

Report on a case in which an 8-year-old girl was injured on the left anterior thoracic wall by two shots fired by her 14-year-old cousin from a soft-air pistol (replica of mod. 17 make Glock, cal. 6 mm, solid plastic bullets); the projectiles caused two skin lesions, both reaching into the subcutis. The results of our own shooting tests with 2 different soft-air pistols and the injuries seen in our case confirm that soft-air pistols may cause penetrating soft-tissue injuries when fired from a short distance.     

Magazine Influence on Cartridge Case Ejection Patterns with Glock Pistols

In this study, the cartridge case ejection patterns of six different Glock model pistols (one specimen per model) were compared under three conditions: firing with a loaded magazine, an empty magazine, and without magazine. The distances, covered by the ejected cartridge cases given these three conditions, were compared for each of the six models. A significant difference was found between the groups of data for each of the tested specimens. This indicates that it is important that, to reconstruct a shooting scene incident based on the ejection patterns of a pistol, test shots are fired with the same pistol type and under the correct magazine condition.     

Characteristics of Backspatter on the Firearm and Shooting Hand—An Experimental Analysis of Close‐range Gunshots

Contact and close‐range gunshot injuries can produce bloodstains on the shooting hand and weapon. In this study, backspatter was analyzed in experimental horizontal pistol shots into blood‐filled sponges. The shooting distances were set between 0 and 45 cm. With increasing shooting distance, there was a significant decrease in the degree of backspatter. Microspatter could be detected on the weapon and shooting hand up to a shooting distance of 40 cm. They were predominantly located on thumb and index finger as well as the radial dorsal aspects of the hand. Fine spray of microspatter combined with elongated droplets in the shape of exclamation marks was found at contact and 2‐cm distance shots. An angular calculation based on the shape of the bloodstains was possible up to a shooting distance of 2 cm. No bloodstains were detected beyond 45 cm.     

Calculating Point of Origin of Blood Spatter Using Laser Scanning Technology

The point of origin of an impact pattern is important in establishing the chain of events in a bloodletting incident. In this study, the accuracy and reproducibility of the point of origin estimation using the FARO Scene software with the FARO Focus^3D laser scanner was determined. Five impact patterns were created for each of three combinations of distances from the floor (z) and the front wall (x). Fifteen spatters were created using a custom impact rig, scanned using the laser scanner, photographed using a DSLR camera, and processed using the Scene software. Overall results gave a SD = 3.49 cm (p < 0.0001) in the x‐direction, SD = 1.14 cm (p = 0.9291) in the y‐direction, and SD = 9.08 cm (p < 0.0115) in the z‐direction. The technique performs within literature ranges of accepted accuracy and reproducibility and is comparable to results reported for other virtual stringing software.     

Police officer involved shootings – retrospective study of situational characteristics

Abstract

The study analyzed the situational characteristics of 112 incidents where police used firearms to handle high threat situations. Most shooting incidents emanated from usually uneventful tasks, e.g., handling burglaries or disturbances. The assailants were commonly armed with firearms (26%), sharp (27%) or blunt objects (10%). The incidents were regularly short-lasting (in 39% were shots fired ≤3 s from threat emerged) and occurred at short distances (in 42% at distances ≤3 m). Predominantly, the first responders had to address the situation and did so with warning shots or, equally common, with fire-for-effect shots (40%) or a combination thereof. Psychological stress was manifested as feelings of panic at some point and as motor skill alterations, e.g., firing without using sights and with one hand only. Analysis of these incidents shows that all field duty police officers should receive training in handling potentially life-threatening, sudden, close-range attacks.     

Fatal impact? The effects of emotional arousal and weapon presence on police officers' memories for a simulated crime

Purpose . (1) To investigate the effects of emotional arousal and weapon presence on the completeness and accuracy of police officers' memories; and (2) to better simulate the experience of witnessing a shooting and providing testimony. Methods . A firearms training simulator was used to present 70 experienced police officers with either a shooting or a domestic dispute scenario containing no weapons. Arousal was measured using both self‐report and physiological indices. Recall for event details was tested after a 10‐minute delay using a structured interview. Identification accuracy was assessed with a photographic line‐up. Results . Self‐report measures confirmed that the shooting induced greater arousal than did the other scenario. Overall, officers' memories for the event were less complete, but more accurate, when they had witnessed the shooting. The recall and line‐up data did not support a weapon focus effect. Conclusions . Police officers' recall performance can be affected both qualitatively and quantitatively by witnessing an arousing event such as a shooting.     

Experimental Effect of Shots Caused by Projectiles Fired from Air Guns with Kinetic Energy Below 17 J

Pursuant to the Polish Weapons and Ammunitions Law (Legal Gazette No 53/1999 item 549 with subsequent amendments), air guns with kinetic energy of the fired projectiles below 17 J are not regarded as weapons. The aim of the study was to assess the potential effect of shots caused by projectiles of various mass and structure fired from air guns with kinetic energy below 17 J on human soft tissues. As a model of soft tissue, we used 20% gelatin blocks. After shooting, we measured the depth of gelatin block penetration by pellets fired from various distances and compared these results with autopsy findings. The results demonstrated that examined pneumatic guns may cause serious injuries, including damage to the pleura, pericardium, liver, spleen, kidneys, femoral artery, and thoracic and abdominal aorta. Experiment shown that gelatin blocks do not reflect fully the properties of the human body.     

Cranial Backspatter Pattern Production Utilizing Human Cadavers

A backspatter pattern results from blood drops that travel retrograde to an applied external force. Historically, an array of animals and nonhuman objects have been used to create and study backspatter patterns. In this study, backspatter patterns captured on foam core targets that were placed 45.72 cm (18 in) behind the impact site (occipital area of the skull) were produced by cranial gunshots to human cadavers that were reinfused with fresh defibrinated bovine blood. These patterns were compared to the backspatter patterns produced by shooting blood‐soaked sponges, a typical simulant used in controlled studies of backspatter pattern production and characteristics. The backspatter pattern produced by shooting an actual human head was found to be different than those of blood‐soaked sponges in the number of stains produced, the size and size range of the stains, and the stain dispersion patterns.     

Accuracy and Repeatability of Trajectory Rod Measurement Using Laser Scanners

Three‐dimensional (3D) technologies contribute greatly to bullet trajectory analysis and shooting reconstruction. There are few papers which address the errors associated with utilizing laser scanning for bullet trajectory documentation. This study examined the accuracy and precision of laser scanning for documenting trajectory rods in drywall for angles between 25° and 90°. The inherent error range of 0.02°–2.10° was noted while the overall error for laser scanning ranged between 0.04° and 1.98°. The inter‐ and intraobserver errors for trajectory rod placement and virtual trajectory marking showed that the range of variation for rod placement was between 0.1°–1° in drywall and 0.05°–0.5° in plywood. Virtual trajectory marking accuracy tests showed that 75% of data values were below 0.91° and 0.61° on azimuth and vertical angles, respectively. In conclusion, many contributing factors affect bullet trajectory analysis, and the use of 3D technologies can aid in reduction of errors associated with documentation.     

Image analysis of gunshot residue on entry wounds: II – A statistical estimation of firing range

A statistical investigation of the relationship between firing range and the amount and distribution of gunshot residue (GSR), used automated image analysis (IA) to quantify GSR deposit resulting from firings into pig skin, from distances ranging between contact and 45 cm. Overall, for a Ruger .22 semi-automatic rifle using CCI solid point, high velocity ammunition, the total area of GSR deposit on the skin sections decreased in a non-linear fashion with firing range. More specifically there were significant differences in the amount of GSR deposited from shots fired at contact compared with shots fired from distances between 2.5 and 45 cm; and between shots fired from a distance of 20 cm or less, with shots fired at a distance of 30 cm or more. In addition, GSR particles were heavily concentrated in the wound tract only for contact and close range shots at 2.5 cm, while the particle distribution was more uniform between the wound tract and the skin surfaces for shots fired from distances greater than 2.5 cm. Consequently, for future scientific investigations of gunshot fatalities, once standards have been established for the weapon and ammunition type in question, image analysis quantification of GSR deposited in and around the gunshot wound may be capable of providing a reliable, statistical basis for estimating firing range.     

Image analysis of gunshot residue on entry wounds. II--A statistical estimation of firing range.

A statistical investigation of the relationship between firing range and the amount and distribution of gunshot residue (GSR), used automated image analysis (IA) to quantify GSR deposit resulting from firings into pig skin, from distances ranging between contact and 45 cm. Overall, for a Ruger .22 semi-automatic rifle using CCI solid point, high velocity ammunition, the total area of GSR deposit on the skin sections decreased in a non-linear fashion with firing range. More specifically there were significant differences in the amount of GSR deposited from shots fired at contact compared with shots fired from distances between 2.5 and 45 cm; and between shots fired from a distance of 20 cm or less, with shots fired at a distance of 30 cm or more. In addition, GSR particles were heavily concentrated in the wound tract only for contact and close range shots at 2.5 cm, while the particle distribution was more uniform between the wound tract and the skin surfaces for shots fired from distances greater than 2.5 cm. Consequently, for future scientific investigations of gunshot fatalities, once standards have been established for the weapon and ammunition type in question, image analysis quantification of GSR deposited in and around the gunshot wound may be capable of providing a reliable, statistical basis for estimating firing range.