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# Wind Drift

#1
05-31-2006, 02:07 PM
 Silver Member Join Date: Jan 2006 Location: Mississippi Posts: 147
Wind Drift

I have read more than a few post on this fourm as well as others. That imply that by going to a heaver bullet or to a larger caliber that you will get less wind drift.
Am I mistaken I thought that the weight or the caliber of the bullet had nothing to do with wind drift. The only thing that matters is time of flight. Which means that velocity and balistic coefficient, are the main factors effecting wind drift.
example of this is if you have two bullets Shoot at 3000 fps and are traveling in a 90 degree ten mph cross wind. bullet A is .243 cal 80 gr with a BC of .534 and Bullet B is a .243 cal 105 gr with a BC of .534. They will have the same wind drift and the same drop and the same time of flight at any given range.

So if I'm wrong will some one please teach me what is correct.

DR B
__________________
Baylor

“ Three rules of Life: If you're too open-minded, your brains will fall out. Don't worry about what people think; they don't do it very often. Artificial intelligence is no match for natural stupidity.
#2
05-31-2006, 02:44 PM
 SPONSOR Join Date: Dec 2004 Location: El Reno, OK Posts: 1,930
Re: Wind Drift

[ QUOTE ]
two bullets Shoot at 3000 fps and are traveling in a 90 degree ten mph cross wind. bullet A is .243 cal 80 gr with a BC of .534 and Bullet B is a .243 cal 105 gr with a BC of .534. They will have the same wind drift and the same drop and the same time of flight at any given range.

[/ QUOTE ]

Your example is 100% correct. It's just that in the real world, as bullet weight increases, so does bc. For example that 80 gr bullet you listed will really hava bc of around .350-.375 where that 105 (depending on manufacturer) will have a bc of .500 to .550 +.

That is why going heavier usually gives you less drift [img]/ubbthreads/images/graemlins/wink.gif[/img].
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Bill "B.J." Bailey
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#3
05-31-2006, 03:32 PM
 Silver Member Join Date: Jan 2005 Posts: 449
Re: Wind Drift

Yes, that's right. Higher BC and velocity gives the bullet a shorter time of flight at a given distance. Bullet weight does not matter, like you said. Bullets of different weights, with the same bc and velocity will have the same wind drift and time of flight. Less time in the air, = less time for gravity and wind to affect the bullet.
#4
05-31-2006, 03:59 PM
 Gold Member Join Date: Nov 2004 Posts: 878
Re: Wind Drift

Technically, its not the time of flight thats the issue in wind drift, its the differance between the time of flight, and the time of flight that would have occured if the bullet had continued at muzzle velocity all the way to the target. Higher BC (heavier) virtually ALWAYS have longer time of flight, but will have less wind drift.
#5
05-31-2006, 04:08 PM
 Silver Member Join Date: Jan 2006 Location: Mississippi Posts: 147
Re: Wind Drift

Bill bailey
My bad Bullet A is .223 80 gr berger VLD not a .243 the BC is correct for the .223 bullet
Dr B
__________________
Baylor

“ Three rules of Life: If you're too open-minded, your brains will fall out. Don't worry about what people think; they don't do it very often. Artificial intelligence is no match for natural stupidity.
#6
05-31-2006, 04:12 PM
 Silver Member Join Date: Jan 2006 Location: Mississippi Posts: 147
Re: Wind Drift

Abnoik
Time of flight is the amount of time that the wind has to act on the bullet. When a object traveles thruogh the Atmosphere the weight has no bering of how fast it drops of how far it drifts.
Dr B
__________________
Baylor

“ Three rules of Life: If you're too open-minded, your brains will fall out. Don't worry about what people think; they don't do it very often. Artificial intelligence is no match for natural stupidity.
#7
05-31-2006, 04:48 PM
 Gold Member Join Date: Nov 2004 Posts: 878
Re: Wind Drift

I agree that weight has no direct bearing on path or wind drift, however, as I mentioned above, its not time of flight that determines wind drift, its the differance between the time of flight, and the time of flight that would have occured if the bullet had continued at muzzle velocity all the way to the target.

Weight only affects the flight of the projectile by its relationship to the ballistic coefficent. BC is sectional density multiplied by form factor. Sectional density is determined by weight and caliber. If the form (shape of the bullet) is held constant, increases in weight raises the sectional density, which reises the BC. Again, only BC and velocity affect wind drift and path. Weight, while a factor in both of these values, is not a direct contribuitor.

Again, Higher BC bullets in the same cartridge, which usually weigh more, will ahve a longer time of flight than lighter bullets, but still have less wind drift.

To put it yet another way, the amount of wind deflection a bullet experences in flight is not directly proportional to the amount of time it is in the air, but rather the differance mentioned above. It is for this reason that vind velocity near the muzzle will result in more deflection than the same wind at a longer range.

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