WebJan 7, 2011 · For years the rule of thumb has been the heaver (or longer) the bullet the faster the twist. This was to stabilize the bullet. A twist rate too slow and bullets would key hole, go through the target side ways. The old Greenhill twist rate formula has been around for years. For rimfire 22's a 1 in 16" twist has been standard for the 22 long rifle. WebMar 27, 2024 · Even when using the "Greenhill" twist rate formula, one inch in the rate of twist, higher or lower doesn't disrupt gyroscopic stability of the bullet in flight, so there would be no advantage for use of the 1:15 twist rate. Jan 24, 2015 #12 M. mohavesam Hawkeye. Joined Jan 4, 2004 Messages

What is Rifling Twist Rate? NRA Family

WebJan 5, 2024 · Iffland HV 223 barrel = 9” twist. All these guns/barrels will stabilize all the bullets shown, suggesting that the Greenhill formula is very conservative, that slower twists than Greenhill will stabilize bullets. Impressions. With a pointy bullet, the point sorta doesn’t count as length, for Greenhill. 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. ... impacts of ww1 on canada

Greenhill Formula for Optimal Rifling Twist Rate - vcalc.com

WebOct 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 … 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. 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. impacts of ww2