I wanted to post a thread for those of you that have trained here at CVT
and for the ones that can't make it. This will be a review of wind reading basics. First thing is our formula: Inches X wind speed / by 1 minute of our distance. We have to have a range card that breaks our wind down to 1 mph. So that it shows us how many inches our bullet will move for every 1 mph of wind speed. Here's link to a ballistic chart you can use. You can fill in the blanks but be sure to only use 1 mph of wind speed rather than 10 mph. http://www.eskimo.com/~jbm/calculations/tr.../traj_card.html
Now it should look something like this:
901 x 576 (167.57K)
Now the one on the left is for 40 degrees and under. The one on right is any over 70 degrees. Remember these are just a starting place. Now notice the column that reads 1 mph wind. Now scroll down to 600 yards. Both cards say at 600 yards your bullet will move 3" (inches) for every 1 mph of wind speed. So if we have a wind speed of 5 mph all we do is multiply 3" x 5 mph= 15" So now we know our bullet will move 15 inches in a 5 mile per hour wind at 600 yards. Now we need to change this to moa so we can dial it in our scope. So we now need to divide our 15 inches by 1 minute of angle of our distance. Which 6" in 1 moa of 600 yards. Right? So 15"/ by 6= 2.5 moa. Now we dial 2.5 moa of wind in our scope depending on which direction it is and we are ready to shoot. Now we must always figure our wind as a full wind (either 3 to 9 or 9 to 3 o'clock) first. Then if our wind is a different direction we simply look at our rosette and multiply our formula by the cosign. Here's the rosette:
1016 x 618 (184.58K)
Now for an example we had a 5 mph wind at 600 yards and for a full wind we dialed 2.5 moa in our scope. Now lets say our wind was coming from 1:30 o'clock. We look at our rosette and the cosign is .707. Now just multiply 2.5 X .707= 1.7675 which is 1.75 moa which is 70% of a full wind value. So with a small plastic oil bottle, we fill it with baking powder and by pointing at our target and squeezing it we can tell exactly what direction the wind is coming from.
Now, first and for most we need to be able to read our natural wind indicators. Shocker!!!! Boys and girls there are no wind flags on the battle field. With that said we need to be able to read our indicators. Here is a good list EShell a great student and friend of mine put together: C.V.T. Wind Indicators
Tactile and Visual Indicators
- 0-1 MPH Wind imperceptible.
- No grass or leaf movement.
- Smoke rises straight up.
- Mirage runs vertical.
- 1-2 MPH Cooling effect of wind may be noticed.
- Light movement of grasses.
- Only a few leaves on any given tree in motion.
- Mirage begins to lean to 12:30.
- 3 MPH Wind pressure can be felt on bare arms.
- Grasses obviously in motion.
- All leaves on any given tree in light motion.
- Mirage leans to 1:00-1:30.
- 4 MPH Wind pressure can be felt on face.
- Small twigs bearing leaf clusters begin light motion.
- Mirage leans to 1:30-2:00.
- 5 MPH Tips of smaller branches begin motion that hold the leaf limbs.
- Mirage leans to 2:00-2:15.
- 6 MPH The trunk branches start to move. These are the heavy limbs holding the smaller branches.
- Mirage leans to 2:15-2:30.
- 7 MPH Larger (trunk) limbs begin motion.
- Young (softer) leaves begin to flip over on windy side of trees.
- Mirage leans to 2:30.
- 8 MPH Tree tops are in light motion.
- Mature leaves flip over on windy side of trees.
- Mirage leans to 2:45.
- 9 MPH Tree tops show obvious movement.
- Almost all leaves flip over.
- Mirage leans to 2:45-3:00 and begins to run.
- 10 MPH Wind pressure can be felt against the body.
- Tree tops show substantial movement.
- Mirage runs slowly and parallel to ground.
- 11 MPH Mirage runs quickly along the ground, begins to break up.
- 12 MPH Wind pressure can be felt against the body.
- Mirage runs very quickly in sheltered places, mostly broken up in exposed areas.
- 12-15 MPH Dust is raised.
- Lighter debris moves around.
- Mirage blows off completely in exposed areas.
- 15-20 MPH Dust clouds blow around.
- Debris blows around.
- Smaller tree trunks sway.
- Major limbs on larger trees in constant motion.
- 20+ MPH Difficulty walking.
- Larger tree trunks sway.
If you would like to book training with Vern Harrison and Central Virginia Tactical, please see his contact information.
It is worth every penny.