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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 ...
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.
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 ...
The components are, from left to right: the solid propellant, the primer, the bullet, and a plastic cap that serves to keep the bullet centered in the propellant block. Modern caseless ammunition typically uses a configuration in which the primer and projectile gets integrated into a solid mass of external propellant (originally nitrocellulose ...
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The above proof round pressure requirements for the 9 mm and 12.7 mm rounds established by the British Ministry of Defence are higher than the current (2008) C.I.P. proof round pressure requirement legislation for the civilian equivalent 9 mm Parabellum (C.I.P. P max rating 235 MPA / (34,083 psi) and .50 Browning (C.I.P. P max rating 370 MPA ...
Wadding is a disc of material used in guns to seal gas behind a projectile (a bullet or ball), or to separate the propellant from loosely packed shots. [1] Wadding can be crucial to a gun's efficiency, since any gas that leaks past a projectile as it is being fired is wasted.