AFTE Store - The Effects of Velocity on Bullet Striations

In firearms identification work, the forensic scientist conducts tests to determine if an unknown projectile was fired from a known suspect weapon. He rarely knows if the test he fires is of the same velocity as the evidence he is to compare. The prupose of this project was to determine if velocity affects intercomparison of fired bullets. Bullets fired at varying velocities from the same firearm were microscopicallycompared to each other to see, if they could be identified as being from the same firearm. When fireing weapons to obtain test bullets for comparison to submitted evidence bullets, it is not always possible to duplicate the evidence bullets’ velocity. This may be due to one or more of the following situations: [1] The type of ammunition that may be received with a firearm may not be the same as the fired ammunition. [2] Similar reference ammunition may be unavailable. [3] The exact type of evidence ammunition cannot be determined. [4] The firearm may no longer be operable, requiring muanual pushing of a “pulled bullet” through the gun barrel. To minimize the number of variables, the forensic scientist/firearms examiner tries to use ammunitin with similar characteristics. These characteristics include: type of primer, bullet shape, bullet composition, cartridge design and bullet veloctiy. Bullet velocity is the most difficult to control and may be greater than, or less than, the velocity of the submitted evidence bullet. The purpose of this prject was to determine is the different velocities of projectiles through weapons affect the identification potential of the projectiles to be matched to one another. This was accomplished by firing a series of bullets of varying velocities from the same firarm. These test firing were then microscopically compared to each other.