Reading the Wind When Hunting

Thomas Haugland, a Shooters’ Forum member from Norway, is a long-range target shooter and hunter. He has created an interesting video showing how to gauge wind velocities by watching trees, grass, and other natural vegetation. The video commentary is in English, but the units of wind speed (and distance) are metric. Haugland explains: “This is not a full tutorial, but rather a short heads-up to make you draw the lines between the dots yourself”. Here are some conversions that will help when watching the video (thanks Boyd):

.5 m/s = 1.1 mph | 1 m/s = 2.2 mph | 2 m/s = 4.5 mph
3 m/s = 6.7 mph | 4 m/s = 8.9 mph | 5 m/s =11.2 mph

To watch this interesting and worthwhile video, click HERE
(or copy and paste the URL: http://www.accurateshooter.com/shooting-skills/reading-the-wind-when-hunting/)

More Interesting Videos from Norway
There are many other interesting videos on Haugland’s YouTube Channel, including Game Stalking,Precision Reloading, and Tips on how to use a Mildot Reticle on a scope with MOA-based clicks.

Reading the Wind — USAMU Tips
(United States Army Marksmanship Unit)

The term, “Reading the Wind” is misleading. A more apt title might be “The tactical negotiation of varying wind conditions and the limitation of their negative effects on the flight of your bullet.” In this article we will discuss some tactics and techniques that will enhance your abilities to negotiate the wind and (hopefully) add a few points to your score. This article will be divided into two sections: Part One will cover the 200- and 300-yard stages. Part Two will be devoted to the 600-yard stage.

There are as many dimensions to “wind reading” as there are stages to High Power competition. Your tactical mindset, or philosophy, must be different for the 200- and 300-yard rapid-fire stages than it would be for the 600-yard slow-fire. In the slow-fire stages you have the ability to adjust windage from shot to shot, utilizing the location of the previous shot as an indicator. Additionally, a change to the existing conditions can be identified and adjusted for prior to shooting the next shot.

Part 1: Rapid Fire at 200 and 300 Yards
Part 2: 600-Yard Firing

To read the full article click HERE
(Or copy and paste the URL: http://www.accurateshooter.com/shooting-skills/readingwind/)

Horizontal Wind-Drift vs. Distance
OK, if the wind is blowing 10 mph from 9 o’clock and if my horizontal wind deflection is .7 inches at 100 yards, what is the drift at 1000 yards?

Well, roughly speaking, since the target is ten times more distant, the wind-drift must be around 7 inches, maybe a little more since the bullet will be slowing down. Seems reasonable right?
WRONG.

Lateral deflection by a 10mph crosswind is (roughly speaking) a function of the square of the distance. In this example, the TRUE deflection is .7″ times (10×10) — about 70 inches!!

I was going through some back issues of Precision Shooting Magazine and this was explained in detail. Now, I remained skeptical, so I checked my Pejsa Ballistics Calculator, which is just about the most accurate program I’ve found to describe the behavior of high BC bullets in flight.

For a 168 Sierra MK (.308), leaving the muzzle at 2700fps with a .464 BC, the numbers are as follows, with a 10mph, 9 o’clock crosswind:

• Drift at 100: .75 moa (3/4″)*
• Drift at 200: 1.57moa (3.14″)
• Drift at 500: 5.06moa (25.3″)

Quoting the article: “Note that the deflections at 100 yards are typically a quarter of those at 200; lateral deflections increase as the square of the range”. Precision Shooting, June 2000, p. 16.

For my 260 Rem load, 123 Scenar (.547BC), 2930fps, same 10mph conditions, Pejsa predicts:

• Drift at 100: .48 moa (1/2″)
• Drift at 500: 2.73 moa (13.65″)
• Drift at 1000: 6.48 moa (64.8″)

Again, even with a higher BC bullet, at 1000yds we end up with something pretty close to the 100-yard deflection (i.e. 1/2″) multiplied by (10×10). Our calculated drift at 1000 is 64.8″ — that’s over 100 times the 100-yard lateral drift in inches, even though the distance has only increased 10x.

* for simplicity, I’m calculating 1 moa = 1″ x distance / 100 .

To read the full article click HERE
(Or copy and paste the URL: http://www.accurateshooter.com/shooting-skills/horizontal-wind-drift-vs-distance/)

FREE Ballistics Software: Use the JBM online ballistics program or download Pejsa and PointBlank Software.

Wind Drift by Gerard Schultz. Excellent technical Article which dispells many misconceptions about bullet performance. Useful charts plotting effect of both BC and distance on wind drift.