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Obturation in firearms and air guns is the result of a bullet or pellet expanding or upsetting to fit the bore, or, in the case of a firearm, of a brass case expanding to seal against the chamber at the moment of firing. In the first case, this both seals the bullet in the bore, and causes the bullet to engage the barrel's rifling. In the ...
Bullet parts: 1 metal jacket, 2 lead core, 3 steel penetrator. Terminal 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. [1]
The bullet must tightly fit the bore to seal the high pressure of the burning gunpowder. This tight fit results in a large frictional force. The friction of the bullet in the bore does have a slight impact on the final velocity, but that is generally not much of a concern. Of greater concern is the heat that is generated due to the friction.
Caliber/calibre: In small arms, the internal diameter of a firearm's barrel or a cartridge's bullet, usually expressed in millimeters or hundredths of an inch; in measuring rifled barrels this may be measured across the lands (.303 British) or grooves (.308 Winchester) or; a specific cartridge for which a firearm is chambered, such as .45 ACP or .357 Magnum.
Gas checks are most commonly found in the form of a thin cup or disc made of a ductile metal. Copper, zinc, aluminum, and alloys such as brass have been used. A bullet designed to accept a gas check has a rebated base shank which permits attachment of the check without altering the maximum diameter of the bullet.
The sabot component in projectile design is the relatively thin, tough and deformable seal known as a driving band or obturation ring needed to trap propellant gases behind a projectile, and also keep the projectile centered in the barrel, when the outer shell of the projectile is only slightly smaller in diameter than the caliber of the barrel ...
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Total metal jacket (TMJ or full metal case) bullets [1] are made by electroplating a thin jacket of ductile metal (usually copper) over a core of different metal requiring protection from abrasion or corrosion. [2] Similar full metal jacket bullets mechanically swage a thin sheet of metal over the core. The swaging process leaves an opening ...