Wind - 3
Windage
Based on the range, wind direction and wind speed, you can now set the windage on your scope.
If you have a windage table specific to your ammunition, use it! Better yet, confirm with your own equipment and ammunition the values in the table and use that.
See the tables page for details on how to use tables.
Quick formula
A quick formula can also give you a quick estimate of the windage to use.
Note 1: it is a ball park figure!
Note 2: use this for .308 ammunition only!
| Range | Wind constant |
|---|---|
| 0-500 | 15 |
| 600 | 14 |
| 700-800 | 13 |
| 900 | 12 |
| 1000 | 11 |
Calculated values
To prove that it gives approximate figures, I calculated all the wind drift values from 100 to 1000 yards for winds, from 5 to 30 MPH and compared them to Federal .308 Gold Match data. The value is in black, the difference in orange. If the difference is greater than 3", I put it red. Make sure you fully realize this error when using this formula!
| Wind speed | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 | 1000 |
|---|---|---|---|---|---|---|---|---|---|---|
| 5 | 0.3 | 1.3 | 3.0 | 5.3 | 8.3 | 12.9 | 18.8 | 24.6 | 33.8 | 45.5 |
| 0.07 | 0.17 | 0.7 | 1.47 | 2.77 | 3.24 | 4.65 | 7.38 | 8.35 | 8.35 | |
| 10 | 0.7 | 2.7 | 6.0 | 10.7 | 16.7 | 25.7 | 37.7 | 49.2 | 67.5 | 90.9 |
| 0.13 | 0.43 | 1.4 | 2.93 | 5.53 | 7.59 | 9.41 | 14.87 | 16.7 | 16.09 | |
| 15 | 1.0 | 4.0 | 9.0 | 16.0 | 25.0 | 38.6 | 56.5 | 73.8 | 101.3 | 136.4 |
| 0.2 | 0.6 | 2.1 | 4.4 | 8.3 | 11.33 | 14.06 | 22.25 | 24.75 | 24.64 | |
| 20 | 1.3 | 5.3 | 12.0 | 21.3 | 33.3 | 51.4 | 75.4 | 98.5 | 135.0 | 181.8 |
| 0.27 | 0.87 | 2.8 | 5.87 | 11.07 | 15.17 | 18.82 | 29.54 | 33 | 33.18 | |
| 30 | 2.0 | 8.0 | 18.0 | 32.0 | 50.0 | 77.1 | 113.1 | 147.7 | 202.5 | 272.7 |
| 0.4 | 1.3 | 4.2 | 8.8 | 16.6 | 22.76 | 27.92 | 44.31 | 50.5 | 49.27 | |
Example
- Data
- Target range: 300 yards.
- Wind speed: 4 MPH, at 90°, left to right.
- 1 MOA at 300 yards: 10.5"
- Use the formula:
- Set your scope for 8.4" windage to the left.
45°
Important point: if the wind is at a 45° angle from you, use 3/4 the value. I know it does not seem intuitively correct, but it is still true. See Maj. J. L. Plaster's book for the complete explanation (see references).
Formulas in this page