My 1,000 Yard Mission
- Thread starter Tangentabacus
- Start date
Kraig, I'm not missing your point; I agree and have shown the max ordinate's 1/2 or a bit further than mid range. 560 to 570 yards in this situation.
My contention is how high above the line of sight it is. 11 to 12 feet above the line of sight for the .308's heavier match bullets is typical for 1000 yard targets. That's nowhere near the 30 feet you've claimed.
Now I gotta say I think you're missing my point.
The .30-06's 150 grain bullet (BC=.346) from machine guns leaving at 2700 fps has a maximum ordinate of 203.30 inches at 590 yards zeroed for 1000. That's just under 17 feet; the highest Berger's software says it goes above the line of sight.
My contention is how high above the line of sight it is. 11 to 12 feet above the line of sight for the .308's heavier match bullets is typical for 1000 yard targets. That's nowhere near the 30 feet you've claimed.
Now I gotta say I think you're missing my point.
The .30-06's 150 grain bullet (BC=.346) from machine guns leaving at 2700 fps has a maximum ordinate of 203.30 inches at 590 yards zeroed for 1000. That's just under 17 feet; the highest Berger's software says it goes above the line of sight.
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The point I'm making is IT DOESN'T MATTER, how high off the ground the max ordinate is, whether its 1 ft, 10, feet or 100 feet.
What does matter is regardless of what you shoot, or how far you shoot the maxi mun ordinate will be between 1/2 and 2/3s distance from the muzzle to the target.
To determine wind correction, one needs to focus on the wind between 1/2 and 2/3s from your position to the target. That is where the bullet will be most venerable to the effects of wind.
Again, it doesn't matter what bullet, what velocity, or what range.
Take my 150 Gr LSWC with the BC of .286 at 1380 fps sighted in at 50 years. The max ordinate of that bullet will be at about 40 yards, or a tad above the 2/3s distance, but still to the point of max wind effect. (not that the wind at 50 yards is gonna throw such a bullet off enough to notice, but the principle is the same).
It would be hard to dispute the fact that the Army Marksmanship Unit has the best shooters in the world. Its their job, in cahoots with the CMP, to teach the military and civilians how to shoot.
To quote from the AMU Service Rifle Guide:
We can argue all day about whether the max ordinate is 10 feet, 20 feet, or 1/4 MOA (as in the 357 case above), it wont change the fact that the bullet will be most effected by wind at a point 1/2 to 2/3s distance to the target. whether that distance is 40 yards in case of the pistol or 700 yardes in the case of the rifle.
And that, what I thought was the orginal point of the discussion, "at what point does one need to read the wind to make adjustments to allow him to hit the target."
What does matter is regardless of what you shoot, or how far you shoot the maxi mun ordinate will be between 1/2 and 2/3s distance from the muzzle to the target.
To determine wind correction, one needs to focus on the wind between 1/2 and 2/3s from your position to the target. That is where the bullet will be most venerable to the effects of wind.
Again, it doesn't matter what bullet, what velocity, or what range.
Take my 150 Gr LSWC with the BC of .286 at 1380 fps sighted in at 50 years. The max ordinate of that bullet will be at about 40 yards, or a tad above the 2/3s distance, but still to the point of max wind effect. (not that the wind at 50 yards is gonna throw such a bullet off enough to notice, but the principle is the same).
It would be hard to dispute the fact that the Army Marksmanship Unit has the best shooters in the world. Its their job, in cahoots with the CMP, to teach the military and civilians how to shoot.
To quote from the AMU Service Rifle Guide:
We can argue all day about whether the max ordinate is 10 feet, 20 feet, or 1/4 MOA (as in the 357 case above), it wont change the fact that the bullet will be most effected by wind at a point 1/2 to 2/3s distance to the target. whether that distance is 40 yards in case of the pistol or 700 yardes in the case of the rifle.
And that, what I thought was the orginal point of the discussion, "at what point does one need to read the wind to make adjustments to allow him to hit the target."
I think under various circumstances you both could be right.
1) IF IF IF wind was exactally constant over the bullet's entire path. In this senario, the above picture of the prone rifleman's bullet drift would be correct. Meaning that a 10 mph crosswind would immediatly effect the bullet's path, and therefore, any immediate deflection counts much greater than deflection later. This scenario migh happen if you were in a tower, shooting across or slightly down towards a target. The wind could even be greater at the muzzle than anything else the bullet sees in it's path, if you were shooting down.
2) normal conditions - where the wind is 5-6 mph at ground level, 15 mph at 15' up. Here, the wind-influence drift would likely be greatest at the 1/2-2/3 distance, because the force of the wind at that higher point in the bullet's path is much stronger. However, if that same force had been acting on the bullet at ground level, you'd be back to scenario 1.
You guys are both right, but in most practical on the ground scenarios, concentrating on the wind at 1/2 - 2/3 of the way to the target will likely get you the best result. Wind velocity is usually variable, increasing with height from the ground. the picture of the marksman above does not take that into account.
1) IF IF IF wind was exactally constant over the bullet's entire path. In this senario, the above picture of the prone rifleman's bullet drift would be correct. Meaning that a 10 mph crosswind would immediatly effect the bullet's path, and therefore, any immediate deflection counts much greater than deflection later. This scenario migh happen if you were in a tower, shooting across or slightly down towards a target. The wind could even be greater at the muzzle than anything else the bullet sees in it's path, if you were shooting down.
2) normal conditions - where the wind is 5-6 mph at ground level, 15 mph at 15' up. Here, the wind-influence drift would likely be greatest at the 1/2-2/3 distance, because the force of the wind at that higher point in the bullet's path is much stronger. However, if that same force had been acting on the bullet at ground level, you'd be back to scenario 1.
You guys are both right, but in most practical on the ground scenarios, concentrating on the wind at 1/2 - 2/3 of the way to the target will likely get you the best result. Wind velocity is usually variable, increasing with height from the ground. the picture of the marksman above does not take that into account.
Yea.... it'll do that.
http://www.youtube.com/watch?v=xesBYKRzqew
30-35 minutes of come up required (around 10MIL if you're using a MIL/MIL scope).
http://www.youtube.com/watch?v=xesBYKRzqew
30-35 minutes of come up required (around 10MIL if you're using a MIL/MIL scope).
Seems there is a small reduction in wind speed from some height above the line of sight down to it. So Kraig's somewhat right. But it's not very much. Over short grass or fallow ground (wide open rifle ranges), at 15 feet above ground it's 15 mph. It'l be about 14.5 mph wind at 11 feet above ground (max ordinate for .308 Win. zeroed at 1000 yards), it will have an 11.5 mph wind at 1 foot above ground where the line of sight is.
But if the wind is constant at all heights, it's easy to figure with ballistic software that the wind closest to the firing point has the greatest effect. One needs to do this to proove my drift numbers in post 29 aren't what one thinks they should be.
Now I wonder what the bullet and ballistic software company's response will be when I email them my complete findings for wind shear numbers over several types of ground.
But if the wind is constant at all heights, it's easy to figure with ballistic software that the wind closest to the firing point has the greatest effect. One needs to do this to proove my drift numbers in post 29 aren't what one thinks they should be.
Now I wonder what the bullet and ballistic software company's response will be when I email them my complete findings for wind shear numbers over several types of ground.
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The problem is, the wind doesn't just effect the bullet along the line of sight.
Line of sight being X, the path of the bullet would be X+.
Lets use an angle firing example to show what I mean.
Lets say you range your target and find its 900 yards away at 15 degrees down (or up).
We know that you multiply 900 by the cosine of 15 degrees or .9659.
So 900 X .9659 = 869.31 yards.
So one adjust his elevation for 869.31 yards. HOWEVER, the bullet is exposed to the bullet the full 900 yards.
So you adjust the elevation for 869.31 and account for the wind for 900 yards.
It's better to use time of flight as to stright line distance as the bullet is effected by the amount of time its expose to the wind as opposed to the distance it travels.
If bullet A takes 2 seconds to get to point X, it be effected twice as much as the same bullet taking 1 second to get to the target.
I not a computer programer, but I'd assume your BC programs take into account the ARC of the bullet to compute TOF rather then line of sight.
Line of sight being X, the path of the bullet would be X+.
Lets use an angle firing example to show what I mean.
Lets say you range your target and find its 900 yards away at 15 degrees down (or up).
We know that you multiply 900 by the cosine of 15 degrees or .9659.
So 900 X .9659 = 869.31 yards.
So one adjust his elevation for 869.31 yards. HOWEVER, the bullet is exposed to the bullet the full 900 yards.
So you adjust the elevation for 869.31 and account for the wind for 900 yards.
It's better to use time of flight as to stright line distance as the bullet is effected by the amount of time its expose to the wind as opposed to the distance it travels.
If bullet A takes 2 seconds to get to point X, it be effected twice as much as the same bullet taking 1 second to get to the target.
I not a computer programer, but I'd assume your BC programs take into account the ARC of the bullet to compute TOF rather then line of sight.
Wind in each column's based on a 15 mph speed 15 feet above the horizontal line of sight. As height decreases, so does wind speed as shown in the table. How much wind speed slows down depends on the terrain.
On typical rifle ranges (short grass, fallow ground) there's not much wind speed difference between the line of sight and maximum ordinate (bullet height above LOS) for 600-yard zeros with either the .308 or .300. More difference happens with a 1000 yard zero.
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