Bullet is a pointed cylinder of lead or other metal that is fired from a pistol, a revolver, a rifle, or a machine gun. Bullets are described by their caliber, which is their diameter in one-hundredths of an inch, or in centimeters or millimeters. A .20-caliber bullet would be 20/100 inch (5.08 millimeters) in diameter. Most rifle and pistol bullets vary between .22 and .60 in caliber. Machine gun bullets can be larger, up to 23 millimeters (90/100 inch).
Ball bullets are the type of bullets used in most army guns and hunting rifles. Tracer bullets contain a substance which leaves a trail of fire along the path of the bullet. Armor-piercing bullets have steel centers and blunt noses. They are used against tanks and other armored targets.
Many bullets are made of lead hardened with small amounts of antimony. Bullets made for firing at high speeds have centers of lead alloy or steel covered with a thin jacket of harder metal. The harder metal can be a copper alloy or steel coated with a copper alloy.
Dumdum bullets have jackets that do not cover the front of the lead core. This makes them more harmful because the soft lead point spreads when it strikes. Such bullets are used in hunting large animals. International law forbids their military use.
The velocity (speed) of a rifle bullet leaving the barrel varies between 600 and 3,000 feet (180 and 1000 meters) per second. Some bullets can hit targets as far away as 6,000 yards (5,500 meters).
