Greenhill twist rate formula
WebFeb 2, 2024 · Greenhill formula: Introduced in 1879 by Prof. George Greenhill, is still used as a rule of thumb to estimate the twist rate t in inches per mm using the equation: t = C … WebTwist rate is expressed as the barrel length required for the projectile to make one complete revolution. For example, 1:10, or 10", is "one turn in ten inches." ... Optimum rates of twist can be calculated by the Greenhill Formula: C = 150 (180 for muzzle velocities exceeding 2,800 f/s) D = bullet's diameter (inches) L = bullet's length (inches)
Greenhill twist rate formula
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WebThe requisite rifle twist rate and bullet stability can be calculated using one of two formulas. The Formula for Greenhill: Prof. George Greenhill first proposed the equation in 1879, … WebNov 5, 2024 · Enter Professor Sir Alfred George Greenhill of the British Royal Military Academy, who devised a formula for determining twist rate which, simplified here, multiplies the square of the bullet diameter by 150 …
WebMay 16, 2013 · Most firearm manufactures use the old Greenhill formula to determine twist rate. It’s a mathematical formula taking into account the bore diameter, bullet length and velocity to come up with an “ideal” twist rate. WebThe Greenhill Formula does not, however, take into account bullet shape or muzzle velocity. Both parameters come into play especially when you approach the limit of what …
WebJun 30, 2011 · Registered. Joined Jan 3, 2003. 1,898 Posts. #5 · Jun 2, 2011. I once pulled and measured some 22WMR 30, 40 and 50 grain projectiles then used the greenhill formula to calculate "ideal" twist rates. I do not have the exact figures anymore but my results were basically. 30 grain = 1:18. 40 grain = 1:16. 50 grain = 1:14. WebGreenhill Formula The formula to determine the correct rate of rifling pitch for bullets of usual construction (lead alloy or jacketed) is known as the "Greenhill Formula". ... This will give the desired rifling twist rate. Example: To find the correct twist for a .30 caliber 220 grain bullet 1.35 inches long. 1.35 : 150 : 33.33 x .30 = 9.999. ...
WebJun 9, 2015 · It is a spread sheet I did based on the Greenhill Formula that uses the diameter and the length of the bullet with some assumptions about the velocity range. See Wikipedia for the details. There are other supposedly more accurate minimal twist rate estimators but I think the accuracy for what minimum twist rate is required needs not be …
WebDec 26, 2007 · Oct 6, 2004. 593. 0. Try this (Greenhill formula) general formula if velocity is under 1800 fps. If the velocity is over 1800 fps sub 180 for the 150 figure. Twist = 150 X D²/L. Where: D = bullet diameter in inches L= bullet length in inches. The formula isn`t exact but is very close for most purposes. Greenhill developed it for the military ... incendium hovering infernoWebOct 8, 2010 · Bottom Line Up Front - The Greenhill Twist Rate formula is not valid for round balls, either mathematically or physically, and the real-world reasons why rifling is beneficial for round balls are not predicted or modeled at all in Greenhill's formula. I don't shoot muzzleloaders, but I'd always wondered why some rifles that shot round balls had … incendium netherWebGreenhill Formula for Optimal Riffling Twist Rate: calculate the optimal barrel twist rate for stabilizing a bullet's flight given the bullet's diameter(D), length(L), specific gravity (SG) … incendium twitterWebJun 2, 2015 · The Greenhill Rifling Formula is used to calculate the optimal barrel twist rate for stabilizing a bullet's flight given the bullet's diameter ( D ), length ( L ), specific gravity ( SG) and velocity ( V ). The resulting twist rate is the length in which the rifling of … The Muzzle Energy of a Projectile formula is used to calculate the energy produced … The Max Ballistic Range calculator computes the maximum range … The Ballistic Coefficient calculator computes the Ballistic Coefficient a factor … ina 237 aggravated felonyWebThe Miller twist rule is better than the Greenhill rifling formula when measuring the specific gravity (SG) of a boat tail bullet because the Greenhill formula was originally … ina 245 - adjustment of statusWebt 2 = 30 m s d 3 l ( 1 + l 2) where. m = bullet mass in grains. s = gyroscopic stability factor (dimensionless) d = bullet diameter in inches. l = bullet length in calibers. t = twist rate in … incendium netheriteWebMar 16, 2024 · Its a formula used to find the optimum bullet length (weight) for your barrel's twist rate. Mr. Greenhill was a military academy instructor from 1876 to 1906. He discovered that the optimum twist rate for a bullet could be determined by dividing 150 by the bullets length in calipers. shape and design of the bullet shows less of an effect in ... ina 301 and 309