The varying size of exit wounds from center-fire rifles as a consequence of the temporary cavity

Experimental Tests on External and Terminal Ballistics of Different Types of Projectiles Fired From .38 SPL Caliber Cartridges and Study of Permanent Cavitation in Anatomical Modeling With 10% Ballistic Gelatin

ABSTRACT

The present study investigated the main morphological differences between the permanent cavities formed by 4 different types of projectiles fired from .38 SPL caliber cartridges in blocks of 10% ballistic gelatin with standardized formulation (Federal Bureau of Investigation Protocol), all fired from the same distance and from the same firearm, associated with its performances in external and terminal ballistics. The velocity or the mass presented by a firearm projectile will not always be solely responsible for the final configuration of the permanent cavity, in which the projectile design, for example, is an equally important element. Each type of projectile tested in the present work generated a different kind of permanent cavity, but they also varied in velocity (m/s) and energy (J). The use of 10% ballistic gelatin in scientific research that seeks to investigate the external and terminal ballistics of projectiles can contribute to the practice of professionals working either in forensic pathology or applied ballistics scenarios, as they can experimentally simulate the events that can occur in the tissues of victims inflicted by gunshot wounds, which also allows important applications in the medical, commercial, civil, and military sectors that deal with products and technologies related to the human body.

Differing sizes of bullet entrance holes in skin of the anterior and posterior trunk

The aim of the present study was to establish whether the size (diameter and area) of bullet entrance holes in skin varies between distant shots to the anterior and posterior trunk, respectively, when using the same ammunition (in concreto pistol cartridges 9 mm Luger). For that purpose, specimens of porcine skin from the belly region and the back were taken (10 samples each) and shot at from a distance of 1.6 m. The entrance holes were photo-documented under standardised conditions. After image processing for contrast enhancement, the maximum diameter and the area of each skin defect were measured automatically by means of an image analysis system. Both size parameters differed significantly depending on the body region affected. On the back with its comparatively thick dermis, the skin defects were considerably smaller than those on the ventral trunk where the corium is less thick. This difference can be explained by the fact that the elastic properties of skin are strongly determined by the connective tissue which is especially rich in fibres. The study results were consistent with the authors’ casework experience and support the assumption that the entrance site of gunshot wounds has a major influence on the size of the bullet hole in skin.

Low-velocity, civilian firearm extremity injuries-review and update for radiologists

Firearm injuries are a preventable epidemic in the USA. Extremities are commonly affected in gunshot injuries. Such injuries may be complex with concomitant osseous, soft tissue, and neurovascular components. The maximum wounding potential of a projectile is determined by its kinetic energy and the proportion of the kinetic energy that is transmitted to the target. Accurate assessment of ballistic injuries is dependent on utilizing the principles of wound ballistics, accurate bullet count, and ballistic trajectory analysis. The goals of this article are to review wound ballistics and the imaging evaluation of extremity civilian firearm injuries in the adult population, with emphasis on ballistic trajectory analysis, specific ballistic fracture patterns, and diffuse, secondary soft tissue ballistic injuries.

The influence of the bullet shape on the width of abrasion collars and the size of gunshot entrance holes

To investigate if there is any correlation between the bullet design and the respective dimensions of the abrasion collar and the skin defect in gunshot entrance wounds, experimental studies were performed on dyed pig skin. For the test shots, .38 Special revolver cartridges with three different bullet designs (round nose, wadcutter, and truncated cone) were used. With the help of an image editing program in combination with an image analyzing system, the area size of the abrasion rings and the skin defects was calculated automatically. The measured values differed significantly depending on the bullet type: the abrasion ring areas were largest in shots with round nose bullets and smallest with wadcutter projectiles. With regard to the entrance hole size, the relationship was inverse. The results are discussed with reference to the pertinent literature concerning the dynamic interaction between bullet and skin.

Bullet fragmentation preceding a contour shot: case study and experimental simulation

In medico-legal literature, only a small number of publications deal with lethal injuries caused by shots with modified guns. This might lead to the conclusion that such cases are extremely rare. However, there are cases again and yet again. During the investigation process, the modified gun is of particular importance since it can show an unusual ballistic behaviour. The present paper reports on a suicide of a 60-year-old man, committed with a modified revolver and a lead bullet. The man had a single gunshot wound with entrance at the right temporal bone. Autopsy revealed that the bullet had fragmented into two major parts. The smaller one stood outside the cranial cavity and pushed its way alongside between the cranial bone and scalp to its end position in the left temporal area. The bigger part entered the cranial cavity and ended in the left parietal lobe. In shots on ballistic soap and on a head-model, the ballistics of the weapon and lead bullet were characterized. The angle necessary for bullet fragmentation was determined by shots on ballistic soap and turned out to be 55°-60° at a velocity of around 200 m/s. This knowledge was transferred to contact shots on a head-model consisting of a layered polyurethane sphere filled with 10 % ballistic gelatine and covered with a skin-like cap almost all around. The resulting injury pattern corresponded to the one of the suicide person. The bigger bullet part entered the skull while the smaller part pushed its way alongside between skin and skull causing an outer contour shot. Furthermore, the revolver was documented firing off two bullets by one trigger pull-a phenomenon of importance for forensic casework the authors have not found reported in forensic literature.

Entrance and exit wounds of high velocity bullet: An autopsy analysis in the event of dispersing the mass rally in Bangkok Thailand, May 2010

Fatal mass casualties by high velocity bullets (HVBs) are rare events in peaceful countries. This study presents 27 forensic autopsy cases with 32 shots fired by 5.56×45mm. HVB (M-16 rifle bullets) during the dispersing the mass rally in Bangkok Thailand, May 2010. It was found that twenty-three (71.88%) typical entrance HVB wounds had round sizes less than the bullet diameters. Most entrance wounds had microtears but no collar abrasion since a HVB has a small streamlined spitzer tip and full metal jacket. For exit wounds, there were various sizes and shapes depending on which section of wound ballistics presented when the bullet exited the body. If a bullet exited in the section of temporally cavity formation, there would be a large size exit wound in accordance with the degree of bullet yaw. This is different from civilian bullets whereby the shape looks like a cylindrical round nose and at low velocity that causes entrance wounds with a similar size to the bullet diameter and is usually round or oval shape with collar abrasion. The temporary cavity is not as large as in a HVB so exit wounds are not quite as large and present a ragged border compared to a HVB. We also reported 9 out of 32 shots (28.13%) of atypical entrance wounds that had various characteristics depending on site of injury and destabilization of bullets. These findings may be helpful to forensic pathologists and to give physicians, who need to diagnose HVB wounds, more confidence.

Wound ballistics of firearm-related injuries--part 1: missile characteristics and mechanisms of soft tissue wounding

Firearm-related injuries are caused by a wide variety of weapons and projectiles. The kinetic energy of the penetrating projectile defines its ability to disrupt and displace tissue, whereas the actual tissue damage is determined by the mode of energy release during the projectile-tissue interaction and the particular characteristics of the tissues and organs involved. Certain projectile factors, namely shape, construction, and stability, greatly influence the rate of energy transfer to the tissues along the wound track. Two zones of tissue damage can be identified, the permanent cavity created by the passage of the bullet and a potential area of contused tissue surrounding it, produced mainly by temporary cavitation which is a manifestation of effective high-energy transfer to tissue. Due to the complex nature of these injuries, wound assessment and the type and extent of treatment required should be based on an understanding of the various mechanisms contributing to tissue damage.