Ballistics
Ballistics is the science that deals with the impact, path, and velocity of
projectiles. Some people say ballistics is the science of projectiles in motion. There are
several different issues while discussing ballistics. Bullet characteristics and comparison
is the first thing. Another issue is the study of terminal, transitional, interior, and exterior
ballistics. The next issue is the instruments used to study the weapon and or bullets in
question and how they test them. After that is the way the court uses ballistics for trials
as well as the experts who determine similarities in the weapons or bullets used in the
crime.
There is some basic terminology of bullet comparisons. Lands is the term gun makers use to represent the original hole size. Grooves are impressed onto the inner surface of a gun barrel to guide and spin the bullet. Grooves are also called riflings. The grooves may twist right or left and the number varies greatly from gun to gun. The grooves are cut with a rifle cutter which is a sharp edged tool with fine saw-like teeth only visible with a microscope. The rifle cutter makes small scratches on the steel inside the barrel while making the grooves. Striations are the imperfections inside the barrel running the full length of the barrel's lands and grooves. Just like fingerprints no two barrels are identical. The caliber is the measure between lands (diameter). The caliber can be measured in two ways. The first way is measured in hundredths of an inch, for example a .22 or .38. The second way the caliber is measured is by millimeters, for example a 9mm or 45mm. When a bullet passes through a barrel the surface is impressed with the rifled markings of the barrel.
Ballistics is divided into four categories, transitional, interior, and exterior
ballistics. Interior ballistics...
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