Misleading Entry Wounds From Atypical Bullet Behavior.

ABSTRACT: Some pistol bullets exhibit atypical wound ballistic behavior that can result in misleading and misinterpreted entry gunshot wounds. We demonstrate the atypical performance and behavior of these bullets using (1) high-speed videography of projectiles penetrating, perforating, and exiting soft tissue simulants; (2) Doppler radar tracking throughout simulated wound production; (3) downrange witness panels to record postperforation bullet orientation during a secondary impact; (4) laser tracking to assess and compare postperforation bullet deflection; (5) evaluation of "bullet wipe" around entry bullet holes in a victim's clothing; and (6) projectile penetration depth for differentiating primary from secondary gunshot wounds. Truncated cone and certain flat-point full-metal-jacketed pistol bullets in the 3 most common calibers of 9 mm, .40 caliber, and .45 caliber typically perforate the victim with little or no yawing, producing straight wound tracks and continuing to travel nose forward upon exiting. Any secondary gunshot victim downrange sustains a normal-appearing entry wound. Common pistol bullets exiting gunshot victims are typically destabilized and enter a yawing or tumbling flight, resulting in entry wounds that appear as typical, first strike entry wounds when in fact, they are secondary gunshot wounds. However, some bullets retain their nose-forward flight after emerging from a gunshot victim. These secondary but normal-appearing, round-shaped entry wounds may be erroneously identified as direct, primary strikes.

The Unique and Misunderstood Wound Ballistics in the John F. Kennedy Assassination.

President Kennedy sustained 2 gunshot wounds on November 22, 1963, in Dallas, Texas, while riding in the right-rear seat of the presidential limousine. The convertible top was down, and no special ballistic protection for the occupants was present.The ballistic events in the assassination and subsequent ballistic evidence were not fully understood then and continue to be misunderstood and often misrepresented today. These facts are largely the consequence of the very uncommon wound ballistic properties of the 6.5-mm Carcano bullets associated with the President's gunshot wounds and the visual responses of the President to his 2 gunshot wounds so often viewed in the 8-mm Zapruder film.An understanding of the wound ballistic characteristics associated with the John F. Kennedy assassination also applies to certain contemporary bullets. Such an understanding could assist forensic pathologists in future cases in evaluating and correctly interpreting gunshot wounds associated with these types of bullets.

Base deformation of full metal-jacketed rifle bullets as a measure of impact velocity and range of fire.

Full metal-jacketed rifle bullets with lead cores and open bases can experience deformation of their cylindrical shapes as they yaw during the penetration of soft tissues. The amount of deformation depends upon the strength of the bullet and the velocity in soft tissue when they go into yaw. The yaw behavior of a bullet in soft tissue depends upon its design (length, ogive shape, ogive length, center of gravity, and pre-impact stability) as it penetrates soft tissue. The yaw characteristics of common spitzer-type military rifle bullets are relatively well known and quite reproducible when fired into suitable soft tissue simulants. This, in turn, results in a relationship between the amount of deformation of the bullet's shank and impact velocity with soft tissue. The specific relationship between impact velocity and bullet deformation must be worked out through empirical testing, but this relationship can be of critical importance in determining impact velocity, which, in turn, relates to range of fire.

The forensic aspects of contemporary disintegrating rifle bullets.

A relatively new type of rifle bullet has appeared in the last few years that contains no lead and rapidly disintegrates into very small particles and jacket fragments immediately upon entry into soft tissue. These bullets are intended for use by 'varmint' hunters in high-velocity centerfire rifles where the effect on such animals as prairie dogs, gophers, ground hogs, and other similarly sized animals is nothing short of explosive. The shooting of much larger animals to include human beings will typically result in nonperforating wounds with short wound paths. X-ray views of a decedent or gunshot victim will lack any recognizable bullet or projectile. Only 1 jacket fragment among the many present in the wound tract is suitable for subsequent firearms identification purposes, namely, the small copper disc that represents the base or heel of the bullet jacket. This small circular fragment bears vestiges of the rifling marks of the responsible firearm.This article will aid the forensic pathologist in recognizing gunshot wounds produced by these atypical bullets and the importance of recovering the base portion of the disintegrated bullet jacket.

Range of fire determination from the pseudostippling of skin by shotshell buffer material.

The plastic buffer material in certain American shotgun shells emerges from the muzzle with the same velocity as the pellets that it was intended to protect from deformation during the very high accelerative forces associated with the discharge process. These small plastic particles spread out quickly over distance in a predictable, reproducible, and uniform manner as they lose velocity because of air resistance. If these plastic particles strike skin with sufficient velocity and energy, they will produce stipple marks whose distribution and density can be used to establish range of fire. This can be of critical importance in the reconstruction of a shooting involving this type of ammunition.

Behavior of expelled glass fragments during projectile penetration and perforation of glass.

Bullets striking common forms of flat glass with an orthogonal intercept angle result in a cloud of ejected glass fragments that are in concert with the exiting bullet's flight path. This is not the case with strikes at angles other than orthogonal. In these situations, the expelled glass fragments follow a very different course from that of the exiting projectile. This is both counterintuitive and a potential source of serious error in the evaluation and reconstruction of a shooting victim's position and orientation at the moment the victim was struck by a bullet that has passed through a nearby source of glass such as a vehicle side window or a window in a building. The flight path of the ejected glass fragments is, however, predictable and is dictated by the orientation of the plane of the glass opposite the projectile's impact site.In all cases, these expelled glass particles have considerable velocity and can produce pseudostippling of the skin in individuals located downrange of bullet-struck glass and near the projectile's exit site. The distribution and location of such pseudostippling and its relationship to the associated bullet hole in glass have important reconstructive value. A proper and reliable reconstruction of the victim's position in such cases will require the integration of scene information with the autopsy findings.

Wound production by ricocheted and destabilized bullets.

Bullets destabilized by ricochet or as the result of an impact with some intervening object experience a yawing to tumbling motion in flight. As a result, they often produce atypical entry wounds, but, as will be demonstrated in this article, this is not a certainty and such bullets can produce normal-appearing entry wounds. It is these wounds that are more difficult to recognize as the consequence of a ricocheted or deflected bullet at the time of autopsy. With few exceptions, ricocheted or deflected bullets also acquire characteristic damage and trace evidence inclusions that often survive the wound production process. A careful inspection of such bullets at the time of recovery will usually reveal such ricochet damage. Moreover, the instability of ricocheted bullets alters their soft-tissue penetration behavior in 2 possible ways. Destabilized full-metal-jacketed bullets will typically penetrate less than direct strikes by the same bullet. Destabilized jacketed hollow-point bullets will often fail to expand and subsequently penetrate more deeply than direct shots with the same bullet.

Physical forms of contemporary small-arms propellants and their forensic value.

Intermediate gunshot wounds typically produce powder tattooing and/or stippling of the skin. The size and density of such powder-induced injuries around an entry wound are used to estimate the separation distance between the muzzle of the responsible firearm and the entry site through test firings at selected muzzle-to-target distances, with ammunition comparable to the injury-producing round and the evidence firearm. The foregoing is well known to forensic pathologists who document and describe such powder patterns in gunshot victims and firearm examiners who customarily produce the test-fired powder patterns for subsequent range-of-fire determinations. Less known, particularly to pathologists, is the considerable variety in forms of modern nitrocellulose propellants, their effects on powder-induced injuries to human skin, and the value of these varied physical forms in the reconstruction of shooting incidents. These factors are the subject of this article.