Terminal ballistics

Terminal ballistics (also known as wound ballistics) is a sub-field of ballistics concerned with the behavior and effects of a projectile when it hits and transfers its energy to a target. Bullet design (as well as the velocity of impact) largely determines the effectiveness of penetration. The concept of terminal ballistics can be applied to any projectile striking a target. Much of the topic specifically regards the effects of small arms fire striking live targets, and a projectile's ability to incapacitate or eliminate a target. Common factors include bullet weight, composition, velocity, and shape. There are three basic classes of bullets: Those designed to maximize accuracy at varying ranges Those designed to maximize damage to a target (by penetrating as deeply as possible) Those designed to avoid over-penetration of a target. This is done by deformation (to control the depth to which the bullet penetrates) which, as a by-product, causes more damage inside the wound. This class may limit penetration by either expanding or fragmenting. For short-range target shooting, typically on ranges up to 50 meters, or 55 yards, with low-powered ammunition like a .22 long rifle, aerodynamics is relatively unimportant, and velocities are low compared to velocities attained by full-powered ammunition. As long as a bullet's weight is balanced, it will not tumble; its shape is thus unimportant for purposes of its aerodynamics. For shooting at paper targets, bullets that will punch a perfect hole through the target —called wadcutters— are preferred. They have a very flat front, often with a relatively sharp edge along the perimeter, which punches out a hole equal to or almost equal to its diameter, thus enabling unambiguous scoring of the target. Since cutting the edge of a target ring will result in a higher score, accuracy to within fractions of an inch is desirable. Magazine-fed pistols tend not to reliably feed wadcutters because of their angular shape. To address this, the semi-wadcutter is often used.