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Barrel time - the time from when the projectile starts to move until it exits the barrel. Diagram of internal ballistic phases. The burning firearm propellant produces energy in the form of hot gases that raise the chamber pressure which applies a force on the base of the projectile, causing it to accelerate. The chamber pressure depends on the ...
Within firearms, chamber pressure is the pressure exerted by a cartridge case's outside walls on the inside of a firearm's chamber when the cartridge is fired. The SI unit for chamber pressure is the megapascal (MPa), while the American SAAMI uses the pound per square inch (psi, symbol lbf/in 2) and the European CIP uses bar (1 bar is equal to 0.1 MPa).
Example of a ballistic table for a given 7.62×51mm NATO load. Bullet drop and wind drift are shown both in mrad and MOA.. A ballistic table or ballistic chart, also known as the data of previous engagements (DOPE) chart, is a reference data chart used in long-range shooting to predict the trajectory of a projectile and compensate for physical effects of gravity and wind drift, in order to ...
Muzzle energy is dependent upon the factors previously listed, and velocity is highly variable depending upon the length of the barrel a projectile is fired from. [2] Also the muzzle energy is only an upper limit for how much energy is transmitted to the target, and the effects of a ballistic trauma depend on several other factors as well.
Miller twist rule is a mathematical formula derived by American physical chemist and historian of science Donald G. Miller (1927-2012) to determine the rate of twist to apply to a given bullet to provide optimum stability using a rifled barrel. [1]
As the bullet moves down the bore, however, the propellant's gas pressure behind it diminishes. Given a long enough barrel, there would eventually be a point at which friction between the bullet and the barrel, and air resistance, would equal the force of the gas pressure behind it, and from that point, the velocity of the bullet would decrease.
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[7] This pressure is reduced by the increasing barrel volume the gas has to fill. In order to achieve maximum muzzle velocity with the shortest barrel length, the projectile should exit the barrel as the gas pressure reduces to a small fraction of the maximum, although unlike maximum chamber pressure, the small fraction desired is impossible to ...