If you still think it is the effect of the wind blowing against the side of the bullet, consider this: In a 10 MPH cross wind, using 150 grain 30 cal bullets launched at 2700 FPS, at 500 yards the Hornady FMJ BT will deflect 12.5". The Hornady RN will deflect 32". Same weight bullet, same general silhouette, same initial speed, but very different deflections. Why?
It's because the RN has a much greater drag vector, so when the bullet noses into the wind, the horizontal component of drag is also much greater.
A model based on the wind blowing against the side of the bullet cannot explain the real-world results that we see.
You have to understand the drag vector thing before you can understand why the bullet follows a slightly corkscrew path during the first part of its trajectory.
My calculations get a 25.8" drift with a 150gr FMJ @2700fps with a 10mph crosswind not 12.5" and 28.1" with a 150grrn @2700fps with a 10mph crosswind.
Hornady
Standard Ballistics Calculator
Instructions
Our ballistics calculator includes both basic and advanced features, allowing you to customize the shooting conditions to replicate your environment. Choose standard or metric, and enter the appropriate data to view your favorite load.
Standard values are provided in the sight height based on the firearm type, but may be changed to match your setup. Default values are entered in the temperature and pressure spaces but can be changed. Once calculated, we offer a printable "cheat sheet" to tape to your firearm for quick reference.
Standard/Metric:
Basic/Advanced:
Description:
Ballistic Coefficient (0.01 - 1.2 )
Velocity (100 - 4600 ft/s)
Weight (5 - 1000 grains)
Maximum Range (100 - 2000 yds)
Interval ( yds )
Zero Range (0 - 2000 yds)
Sight Height (0.1 - 4 inches)
Drag Function
Shooting Angle (-90 - 90 degrees)
Wind Speed (0 - 70 mph)
Wind Angle (0 - 359 degrees)
Altitude (0 - 15000 ft)
Pressure (15 - 40 hg)
Temperature (-40 - 140 F)
Humidity (0 - 100 %)
Input Variables
Basic
- Standard/Metric: Choose the system of measurement you want to use.
- Description: Use this space to describe the handload or factory ammo you’re using.
- Ballistic Coefficient: Refer to the trajectory data. (Must be at least .001 up to 1.0)
- Velocity: Measured in feet per second, or meters per second. (must be between 100 and 4400 fps, or 30 - 1350 m/s)
- Weight: Bullet weight in grains (must be at least 5 grains up to 300 grains)
- Maximum Range: The furthest range to which you want to calculate. (from 100 to 1000 yards, or 30 to 1000 meters)
- Interval: The range interval you want to calculate and display.
Advanced
- Drag Function: Use either the G1 or G7 model. This will depend on the bullet you are using.
- Sight Height: The default is 1.5in/5cm. Can be from .1 to 4 inches/.1 to 10 cm.
- Shooting Angle: The vertical angle between you and the target. A negative angle indicates you are above the target. A positive angle indicates you are below the target.
- Zero Range: Defaults to 100 yds/50 meters.
- Wind Speed: Measured in miles per hour/km per hour.
- Wind Angle: This indicates the direction of the wind. 0 degrees is a direct headwind. 90 degrees is a crosswind from the right. 180 degrees is a direct tailwind. 270 degrees is a crosswind from the left.
- Altitude: Your height above sea level.
- Pressure: Enter the absolute barometric pressure for the shooting site, standard pressure is default.
- Temperature: Enter in degrees Fahrenheit or Celsius.
- Humidity: Entered as a percentage.
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Results
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Your Input Variables
Ballistic Coefficient 0.186 Velocity (ft/s) 2700 Weight (grains) 150
Maximum Range (yds) 500 Interval (yds) 100 Drag Function G7
Sight Height (inches) 1.5 Shooting Angle (degrees) 0 Zero Range (yds) 100
Wind Speed (mph) 10 Wind Angle (degrees) 90 Altitude (ft) 0
Pressure (hg) 29.53 Temperature (F) 59 Humidity (%) 0.78
Ballistics Results
Range (yards) Velocity (fps) Energy (ft.-lb.) Trajectory (in) Come UP in MOA Come UP in Mils Wind Drift (in) Wind Drift in MOA Wind Drift in Mils
Muzzle 2700 2428 -1.5 0 0 0 0 0
100 2463 2021 0 0 0 1 0.9 0.3
200 2239 1669 -4.3 2 0.6 3.9 1.9 0.5
300 2025 1366 -15.5 4.9 1.4 9.1 2.9 0.8
400 1823 1107 -35.2 8.4 2.4 17.1 4.1 1.2
500 1632 887 -65.5 12.5 3.6 28.1 5.4 1.6
The following table is provided as a "cheat sheet" that you can tape to your gun.
Your Round 150 gr. 0.186 B.C.
Range Muzzle 100 200 300 400 500
Trajectory -1.5 0 -4.3 -15.5 -35.2 -65.5
Come UP in MOA 0 0 2 4.9 8.4 12.5
Come UP in Mils 0 0 0.6 1.4 2.4 3.6
Wind Drift 0 1 3.9 9.1 17.1 28.1
Wind Drift in MOA 0 0.9 1.9 2.9 4.1 5.4
Wind Drift in Mils 0 0.3 0.5 0.8 1.2 1.6
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