The external ballistics of a bullet's path can be determined by several formulae, the simplest of which is: (Jandial et al, 2008) External ballistics (from gun to target) The effect upon the subsequent flight path of the bullet is usually insignificant. This results from minor (rarely major) imperfections or variations in rifling or tool marks within the barrel. (Volgas, Stannard and Alonso, 2005)Īs the bullet traverses the barrel of the gun, some minor deformation occurs, called setback deformation. Up to a point of diminishing pressure, the longer the barrel, the greater the acceleration of the bullet. Bullet travel through a gun barrel is characterized by increasing acceleration as the expanding gases push on it, but decreasing pressure in the barrel as the gas expands. The last of these factors is a function of barrel length. Therefore, the energy transmitted to the bullet (with a given mass) will depend upon mass times force times the time interval over which the force is applied. The area here is the base of the bullet (equivalent to diameter of barrel) and is a constant. The controlled expansion of gases from burning gunpowder generates pressure (force/area). It is difficult in practice to measure the forces within a gun barrel, but the one easily measured parameter is the velocity with which the bullet exits the barrel (muzzle velocity) and this measurement will be used in examples below.
Higher pressures require a bigger gun with more recoil that is slower to load and generates more heat that produces more wear on the metal. More powder can also be used in rifle cartridges because the bullet chambers can be designed to withstand greater pressures (50,000 to 70,000 for rifles psi vs. (Fackler, 1996) Internal, or initial ballistics (within the gun)īullets fired from a rifle will have more energy than similar bullets fired from a handgun. The wounding potential of projectiles is a complex matter. The flight path of a bullet includes: travel down the barrel, path through the air, and path through a target.
The term ballistics refers to the science of the travel of a projectile in flight.
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