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Posted: 1/2/2014 11:19:39 AM EDT
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I have a number of bolt action 308's. Really nice guns. Three of them have a 1 in 10 twist and the other has a 1 in 12.
I also have four 223 bolt action rifles. Here the rates of twist are 1 in 8, 1 in 9 and 1 in 12. What I'd appreciate help on is, first, what bullet weights would you recommend for these two? I'd like to use only one bullet per cartridge. And, second, is there a single powder that would work well in both the 223 and 308? |
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Just so you know, the weight of the bullet has no relationship to the twist rate and vice versa. The ONLY factors you need to know is:
velocity of the bullet LENGTH of the bullet (not weight) twist rate There is a formula called the Greenhill Twist Rate formula: 
where: C = 150 (use 180 for muzzle velocities higher than 2,800 f/s) D = bullet's diameter in inches L = bullet's length in inches SG = bullet's specific gravity (10.9 for lead-core bullets, which cancels out the second half of the equation) |
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Quoted:
Just so you know, the weight of the bullet has no relationship to the twist rate and vice versa. The ONLY factors you need to know is: velocity of the bullet LENGTH of the bullet (not weight) twist rate There is a formula called the Greenhill Twist Rate formula: http://upload.wikimedia.org/math/d/8/9/d897ff3697a3bbde34972528dbaf3dc4.png where: C = 150 (use 180 for muzzle velocities higher than 2,800 f/s) D = bullet's diameter in inches L = bullet's length in inches SG = bullet's specific gravity (10.9 for lead-core bullets, which cancels out the second half of the equation) Thanks! Any idea as to how to come up with a bullet's length? |
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Quoted:
Thanks! Any idea as to how to come up with a bullet's length? Quoted:
Quoted:
Just so you know, the weight of the bullet has no relationship to the twist rate and vice versa. The ONLY factors you need to know is: velocity of the bullet LENGTH of the bullet (not weight) twist rate There is a formula called the Greenhill Twist Rate formula: http://upload.wikimedia.org/math/d/8/9/d897ff3697a3bbde34972528dbaf3dc4.png where: C = 150 (use 180 for muzzle velocities higher than 2,800 f/s) D = bullet's diameter in inches L = bullet's length in inches SG = bullet's specific gravity (10.9 for lead-core bullets, which cancels out the second half of the equation) Thanks! Any idea as to how to come up with a bullet's length? http://www.jbmballistics.com/ballistics/lengths/lengths.shtml once you have the length use this to calculate stability http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi |
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Quoted:
Just so you know, the weight of the bullet has no relationship to the twist rate and vice versa. The ONLY factors you need to know is: velocity of the bullet LENGTH of the bullet (not weight) twist rate There is a formula called the Greenhill Twist Rate formula: http://upload.wikimedia.org/math/d/8/9/d897ff3697a3bbde34972528dbaf3dc4.png where: C = 150 (use 180 for muzzle velocities higher than 2,800 f/s) D = bullet's diameter in inches L = bullet's length in inches SG = bullet's specific gravity (10.9 for lead-core bullets, which cancels out the second half of the equation) This is especially a big deal for Barnes bullets |
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