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Conventional eight groove rifling on the left, and octagonal polygonal rifling on the right. Polygonal rifling (/ p ə ˈ l ɪ ɡ ə n əl / pə-LIG-ə-nəl) is a type of gun barrel rifling where the traditional sharp-edged "lands and grooves" are replaced by less pronounced "hills and valleys", so the barrel bore has a polygonal (usually hexagonal or octagonal) cross-sectional profile.
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 ...
The caliber is the diameter of the barrel. The twist is the direction of the striations left by the barrel's rifling, clockwise (right-handed) or counterclockwise (left-handed). Most barrels will have a right-handed twist with the exception of weapons created by the Colt's Manufacturing Company which uses left-handed twists.
Attaching the barrel to the receiver using a barrel nut and a barrel with a shoulder is an alternative to action threads, which has been used in firearms such as the Sten gun and AR-15. Hand tools Quick barrel change systems is an increasingly popular alternative, as seen in for example SIG Sauer 200 STR, Roessler Titan or Blaser R8.
A female worker boring out the barrel of a Lee-Enfield rifle during WWI. Gun barrels are usually made of some type of metal or metal alloy.However, during the late Tang dynasty, Chinese inventors discovered gunpowder, and used bamboo, which has a strong, naturally tubular stalk and is cheaper to obtain and process, as the first barrels in gunpowder projectile weapons such as fire lances. [2]
The energy conversion efficiency of a firearm strongly depends on its construction, especially on its caliber and barrel length. However, for illustration, here is the energy balance of a typical small firearm for .300 Hawk ammunition: [1] Barrel friction 2%; Projectile motion 32%; Hot gases 34%; Barrel heat 30%; Unburned propellant 1%.
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In order to make accurate predictions on gyroscopic drift several details about both the external and internal ballistics must be considered. Factors such as the twist rate of the barrel, the velocity of the projectile as it exits the muzzle, barrel harmonics, and atmospheric conditions, all contribute to the path of a projectile.