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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]
Rifling of a 105 mm Royal Ordnance L7 tank gun Conventional rifling of a 90 mm M75 cannon (production year 1891, Austria-Hungary) Rifling in a GAU-8 autocannon. Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy.
At its introduction the rifle came with a 24-inch barrel and was chambered for a variety of rounds such as .25-20 Winchester, .32-20 Winchester, .38-40, and .44-40. Variants in other chamberings remain in production today. [1] Even though both are lever-action rifles and named similarly, the Marlin 1894 is different from the Winchester Model 1894.
The Marlin Model 336 is a lever-action rifle and carbine made by Marlin Firearms.Since its introduction in 1948, it has been offered in a number of different calibers and barrel lengths, but is commonly chambered in .30-30 Winchester or .35 Remington, using a 20- or 24-inch barrel.
Before the barrel can release the bullet in a consistent manner, it must grip the bullet in a consistent manner. The part of the barrel between where the bullet exits the cartridge, and engages the rifling, is called the "throat", and the length of the throat is the freebore. In some firearms, the freebore is zero as the act of chambering the ...
Early production rifles had a 1:12 twist rate and post-2014 rifles have the 1:9 twist rate. [2] The CZ 527 Varmint in .223 has muzzle velocities for standard-load 45-grain (2.9 g) ammunition of around 3,500 feet per second (1,100 m/s). The 1:9 barrel twist in the Varmint Kevlar reduces muzzle velocities by about 1.5%.
To obtain maximum accuracy, bullet weight and form are matched to the rifling twist rate of the barrel. Typically, 68 gr (4.41 g) bullets are used in barrels with twist rates of 1 in 13 inch (1 in 330 mm), while 1 in 15 inch (1 in 380 mm) barrel twists can accommodate lighter 58 or 60 gr (3.76 or 3.89 g) accurately.
The stock is attached to the barrel, and the barrel to the action. The rifled barrel has a twist rate of 1 turn in 20", allowing heavy hunting bullets to stabilize. This is relatively rare for .44 Magnum firearms, which usually are rifled at a rate of 1 turn in 38 inches. The 1:20" twist enables the use of 325gr ammunition for hunting large ...