Advanced Marksmanship HELP with WIND direction and correction

[crossgun]

Looking for a little help and clarification as believe it or not I’m confused.

First of all it’s my understanding that wind direction is reported from the direction it originates?

I use Ballistic FTE and a few others so a wind of 270 or 9 o'clock would be an L to R wind? 90 or 3 o'clock would be R to L?

JBM say this
<span style="font-weight: bold">Wind Angle
Angle of the wind direction. A wind blowing downrange has an angle of zero, a wind blowing to the shooter's right has an angle of 90, a headwind, an angle of 180 and a wind blowing to the shooter's left has an angle of 270 degrees.</span>

I don’t believe this to be the norm from what I understand and what my Ballistic FTE and others indicate.

I also am having difficulty with understanding the +/- related to windage adjustments as they appear on my software and iPod touch. With Ballistic FTE I get a negative number with 270 degree or 9 o'clock wind which I know means I have to dial L to correct. Get positive numbers for 90 or 3 o'clock wind which would require dial R to correct.

With Mil Dot Ballistics I get the opposite with regard to the +/-

Would one of you guys please explain?

I also don’t understand this statement from JBM as well and would like some clarification.
<span style="font-weight: bold">Windage
The distance to the right or left of the line of sight. Windage is positive to the shooters right and negative to the shooters left</span>

HELP!

 

[Sterling Shooter]

Re: HELP with WIND direction and correction

Wind direction is from the perspective of you the big hand in the middle of a clock shooting at 12 o'clock. What's important is knowing, that from this perspective, wind direction has a value. For example, a cross wind of 10 mph is a full value wind. The same 10 mph wind from let's say 11 to 5 would be placed in your wind formula as a 1/2 value, or a 5 mph wind. A wind from 6 to 12, or 12 to 6 would have no value.

My advice, learn what wind looks and feels like, for example a wind raising dust and moving loose paper could be treated as an 8 to 12 mph wind and one which you'd average to 10 mph. With knowledge for wind velocity and direction you can enter it into a simple formula, like distance divided by 100, times velocity in mph, divided by 10, equals drift in MOA. The constant of 10 is not perfect but it's fast, and will get the job done for B.C.'s in the .308 and .223 range.

Shooting at 600 yards with a 10 mph cross wind at mid-range would mean 6 times 10 divided by 10 equals 6 MOA, or 36 inches of favor.

I'm not going to tell you to throw away all your charts, graphs, wind meters, but, seriously, this stuff can be figured in your head in a heartbeat, and, that's important, since wind can change in a heartbeat.

 

[TOP PREDATOR]

Re: HELP with WIND direction and correction

POOR MAN's WIND SPEED GUESTIMATION - get a ribbon of paper, hold it out to 90*, then drop it. when it hits the ground point to it, estimate the angle. divide that angle by 4, and you have a guestimation of wind speed at your location

WIND DIRECTION CALIBRATION / ANGLE OF PREVAILING WIND IN RELATIONSHIP TO SHOOTER

WIND VALUE:

1:00 = .5 1/2 VALUE OF 1 MPH
1:30 = .75 3/4 VALUE OF 1 MPH
3:00 = 1.0 FULL VALUE OF 1 MPH
4:30 = .75 3/4 VALUE OF 1 MPH
5:00 = .5 1/2 VALUE OF 1 MPH
6:00 = 0 0 VALUE OF 1 MPH

EXAMPLE: Using (5 MPH WIND)

12:00 = 0 (12:00 is your target while you are pointing the rifle at it...the target is always 12:00) theoritically, no drift shooting directly into the wind.
1:00 = 2.5 MPH.......5MPH wind X .5 = adjusted wind speed of 2.5 MPH
1:30 = 3.75 MPH......5MPH wind X .75 = adjusted wind speed of 3.75 MPH
3:00 = 5 MPH..........5MPH wind X 0 value = full value or 5 MPH
4:30 = 3.75 MPH......5MPH wind X .75 = adjusted wind speed of 3.75 MPH
5:00 = 2.5 MPH........5MPH wind X .5 = adjusted wind speed of 2.5 MPH
6:00 = 0 MPH (6:00 is directly behind you as you face the target) theoritically, no drift as you would be shooting with the wind.

FORMULA: WIND MPH X WIND DIRECTIONAL VALUE (decimal) = ADJUSTED WIND SPEED

it's like a boat crossing a river; if you are perpendicular to the current, you are getting the full effect of the current (full value)

row across at an angle and you'll have less effect of the current against the boat (1/2 and 3/4 value)