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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.
Firearm muzzle velocities range from approximately 120 m/s (390 ft/s) to 370 m/s (1,200 ft/s) in black powder muskets, [3] to more than 1,200 m/s (3,900 ft/s) [4] in modern rifles with high-velocity cartridges such as the .220 Swift and .204 Ruger, all the way to 1,700 m/s (5,600 ft/s) [5] for tank guns firing kinetic energy penetrator ammunition.
Another attempt at building a ballistic calculator is the model presented in 1980 by Dr. Arthur J. Pejsa. [18] Dr. Pejsa claims on his website that his method was consistently capable of predicting (supersonic) rifle bullet trajectories within 2.5 mm (0.1 in) and bullet velocities within 0.3 m/s (1 ft/s) out to 914 m (1,000 yd) in theory. [19]
The .225 Winchester was chambered in factory rifles by Winchester (Models 70 and 670) and Savage (Model 340). All commercially produced rifles chambered in .225 Winchester were turn-bolt or break actions.
Most rifle cartridges have a high load density with the appropriate powders. Rifle cartridges tend to be bottlenecked, with a wide base narrowing down to a smaller diameter, to hold a light, high-velocity bullet. These cases are designed to hold a large charge of low-density powder, for an even broader pressure curve than a magnum pistol cartridge.
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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 ...