Wind Drift May Be The Reason You Missed That Shot

The two largest problems to solve when shooting long distances are bullet drop and wind drift. With an accurate range finder and with knowledge of our bullet’s ballistics, we should be able to make adjustments and correct for bullet drop. Measuring and correcting for wind drift is more complicated and I am convinced that failure to dope and correct for the wind is the main reason the average shooter misses or wounds animals when shooting at distances over 200 yards.

wind drift of bullet shot at elk

Figure 1. Wind drift at 20 mph with 160 grain 7mm Remington Magnum Bullet at 450 – 550 yards, zero at 200 yards, elevation adjusted for 500 yards. (click photo for larger image)

What Do You Think Caused the Bullet to Miss?

Why do you think you, your hunting buddy or that guy on the hunting show missed or wounded an animal? How about the hunter that got lucky and made a clean neck shot when aiming for the heart-lung area? I’ve seen that on hunting shows too.

Yes, a combination of problems can cause a miss. For situations like a moving animal, a rushed shot, a shooter in an unstable position (“scope-bite” is due to rushed shot or unstable position), it’s easy to understand how shots were missed (and maybe should not have been taken).

For shots that were two feet high or low, perhaps the range finder reading was rushed, resulting in the wrong distance, but it takes a huge distance error to cause a 20+ inch vertical shooting error. But it’s more likely the shooter simply used an incorrect holdover for the distance. Anyway, these are rookie mistakes from too much excitement and/or too little practice shooting.

What about all those situations when the shooter appears to have time and a stable shooting position? It’s hard to know for sure, but most of the misses I see appear to be due to the wind.


Wind Drift with 7 mm Remington Magnum

Even a very flat shooting caliber like the 7 mm Remington Magnum, drops very quickly after the first 200 yards. For example, a 160 grain bullet drops almost 37 inches between 200 – 500 yard. If shooting at a kill zone of 6 – 10 inches, that is plenty of room to make a mistake and at best completely miss an animal and at worst, wound the animal (Read Effect of Distance Estimation Errors on Bullet Impact.

A 20 mph wind will drift the 7 mm bullet almost 27 inches at 500 yards (see Table 1), so there is more potential vertical error due to distance, but with basic tools like range finder,  a ballistics calculator and practice will solve bullet trajectory problems. Estimating wind speed and calculating wind drift is the big problem when shooting at game.

Table 1. Wind Drift of 7 mm Remington Magnum

wind drift of 7mm remington magnum bullet

Ballistic  &  Environmental Assumptions:

  • Bullet – 7mm Remington Magnum with 160 grain bullet (Federal Premium Vital Shok with Barnes Triple Shock X-Bullet)
  • Ballistics – Bullet B.C. = 0.508, muzzle velocity = 2,940 fps
  • Scope Height = 1.5 inches
  • Zero at 200 yards
  • Wind 20 mph @ 90°
  • Setting – Elevation 5,600 feet, 60°F
  • Download the free Ballistics Calculator from Point Blank
  • Note – Point Blank calculates 10 mph wind drift, so double it for 20 mph wind

Why Assume 20 MPH Wind?

First, let me explain why I assume a 20 mph wind. I researched average wind speed for Colorado, Montana, Utah and Wyoming and about 60% of those areas average wind speeds between 10-20 mph. So it is very common to have 20 mph winds in much of the area. We can hope for a calm day, but when hunting in the West, you had better be prepared to shoot in the wind and be glad when it’s not laying the grass down and blowing 35 mph.

Table 1 shows wind drift (in inches) for 10, 20 and 30 mph cross winds (90°). Drift values greater than 10 inches are in dark gray and values greater than 5 inches are light gray as warning zones. Anytime the amount of wind drift approaches the size of the kill zone, the shot should be questioned. So anytime the wind is 10 mph, any shot over 300 yards should be carefully considered. If the wind is blowing 20 mph, any shot of 200 yards has to be taken with caution. No shot over 400 yards should be taken casually in any amount of wind.

Bullet Wind Drift Scaled to an Elk

What does this amount of wind drift look like compared to an animal? You can see in Figure 1, how bullet drift from a 20 mph crosswind  (both right and left) looks like against an elk standing broad side. Scale is based upon the average bull elk standing 58 inches at the shoulders. The zero (0 inches on the vertical scale) is set for 200 yards. The circle is scaled to 14 inches, which is a very realistic kill zone for an elk. Our goal should be to hit within an 8 or 10 inch circle but the larger kill zone further illustrates the magnitude of wind drift.

In Figure 1, the shot is set up for a 500 yard shot and a wind blowing left to right if not corrected would move the bullet 26.6 inches (Table 1) and strike the elk in the knee and/or the hind gut. If the wind were blowing right to left (and not corrected), the bullet would completely miss the animal.

You can also see that if the elevation had been adjusted for a 450 yard shot, the left to right wind would cause a hit in the gut and a right to left wind would graze the neck. A shot at 550 yards would either hit the hind leg or miss further in front of the elk.

wind drift of bullet shot at elk

Figure 2. Wind drift at 20 mph with 160 grain 7mm Remington Magnum Bullet at 200 – 550 yards, zero at 200 yards, elevation adjusted for 400 yards. (click photo for larger image)

Figure 2 shows a closer distance, with the hold over set for a 400 yard shot. A wind blowing left to right would move the bullet 16.4 inches (Table 1) and strike the elk in the gut. If the wind were blowing right to left (and not corrected), the bullet would hit the elk low in the throat.

If the shot had been 350 yards, the left to right wind would cause a hit in the gut and a right to left wind would hit the neck just in front of the shoulder.

wind drift of bullet shot at elk

Figure 3. Wind drift at 20 mph with 160 grain 7mm Remington Magnum Bullet at 200 – 400 yards, zero at 200 yards, elevation adjusted for 300 yards. (click photo for larger image)

Figure 3 shows a shot set up for 300 yards and where a 20 mph wind will move the 7 mm bullet 9.1 inches (Table 1) and strikes the elk two inches outside of the 14 inch kill zone on either side. The bullet strikes either the gut or in the shoulder or neck area.

For  250 yard shot, the bullet moves 6.3 inches and strikes just inside the kill zone on either side and at 200 yards, the bullet moves only 4.1 inches and hits almost 3 inches inside the kill zone on either side.

So, we either have to do a very good job of estimating and correcting for the wind, or we have to get closer so the wind has less effect or the bullet.

If you have put in the work and have a high probability (85 – 90%) of making a long range shot in the wind, good for you. Most of us should probably just admire the animal for a minute or two at that distance, then try to get closer.

I test my skills when shooting at milk jugs and paper targets (Read post on Realistic Target Practice), but I am very conservative when shooting at game in the wind at any distance over 200 yards. I love to hunt and I love to eat elk and venison, but I hate the idea wounding and tracking wounded animals. It’s just not worth it to me. I have passed on many shots and eaten tags because of it, but I have no regrets and look forward to hunting again the next day. The good thing about passing on shots is you get to hunt again the next day as long as it’s not the last day.

Comments

  1. Richard M Caldwell says:

    Enjoy and appreciate all the info. Very interesting something all of us should consider. But how many really do? The reason for so many wounded or missed animals. Thanks.

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