point where it penetrates the skin can influence the shape of the abrasion collar. This can be used by forensic pathologists in discerning an approximate angle of entry and is important in investigations of gunshot wound victims, where evidence of the gunshot's origin is necessary to determine whether the death was homicidal, suicidal, or accidental. Generally, if the bullet impacts at an angle perpendicular to the skin surface, the abrasion collar will be symmetrical, concentric, round, and evenly-shaped. As the angle between the trajectory and the skin surface decreases, the abrasion collar becomes more distorted and often more distinct at the point of entry, having a semi-lunar or "half-moon" shape with the broadest width pointing in the direction of the gunshot's origin. This is caused by the exterior of the bullet contacting and scraping over the skin's surface for a certain distance before penetrating the skin. Bullet shape and velocity The bullet shape influences the size of the abrasion collar. High velocity bullets with pointed, narrow, or spitzer tips, such as rifle rounds, and full metal jacket bullets are less likely to produce abrasion collars compared to lower-velocity, semi-jacketed civilian bullets, such as bullets fired from handguns, which have rounded noses. If the wound is caused by a high-velocity rifle bullet, the abrasion collar may be smaller, but it may have minute tears in the surface of the skin surrounding the wound entrance. This is because the skin is not capable of stretching quickly enough if the bullet's velocity is too high. If the wound is made over bone, such as a head wound in the scalp, the abrasion collar may not be round at all; it instead becomes stellate or "star-shaped" with ragged and torn edges caused by the skin over-stretching and tearing. In the case of skull entrance wounds, the skin that includes the abrasion collar may be torn away because the underlying tissue is unable to flex away from the force of the bullet's entry. Wound distortions Towards the end of a bullet's effective range, it tends to lose axial stability and will begin to yaw or even tumble end-over-end. This means it may impact the skin while travelling sideways, and the resulting wound may be distorted, irregular in shape, or even slit-like, such that it does not resemble a conventional entrance wound. In this case, an abrasion artefact may be absent. Similarly misshapen wounds can be