Wind Invisible But Decisive

Full-size Leica Geovid 7x42mm binoculars are both great glass and an excellent laser rangefinder.

A distinguished rifleman once told me, "A plinker studies trajectory tables; a master studies the wind." His point was well taken.

While accurate range estimation is absolutely essential, most long-range shooters learn to judge distances and compensate correctly. They know it's important, so they do it.

But that leaves the other great factor of longrange accuracy—wind estimation—and here is

U.S. Marines in Iraq with Designated Marksman Rifle and Vector laser ranging system.

Sniper Training Wind Calculations

RELATIVE WIND EFFECTS

Soon after publication of The

Ultimate Sniper in 1993, I received

letters critical of how I'd explained wind

effects and their required compen

sation. Having never

seen other than

the stylized illustrât

'ons in military

manuals, the writers insisted I had it

wrong and, for instance, a 45-degree

wind was 1/2 value, not the 3/4 value I'd

described. (Though that's incorrect, it

would seem logical since 45 is half of

90, or half of a full-value wind.) So that

you can see exactly what these values

are, here's the multiplier factor table

used by Sierra Bullets, which verifies

my original data.

Wind Angle to

Required

Bullet Path

Multiplier

0 Degrees

0.000

5 Degrees

0.087

10 Degrees

0.174

15 Degrees

0.259 *

20 Degrees

0.342

25 Degrees

0.423

30 Degrees

0.500 **

35 Degrees

0.574

40 Degrees

0.643

45 Degrees

0.707 ***

50 Degrees

0.766

55 Degrees

0.819

60 Degrees

0.866

65 Degrees

0.906

70 Degrees

0.940

75 Degrees

0.966

80 Degrees

0.985

85 Degrees

0.996

90 Degrees

1.000 ****

* 1/4 value

** 1/2 value

*** 3/4 value

**** Full value

similar to that of the higher winds but turned around as it passed down the gorge.

The presence of such contradictory winds is far more frequent than most people realize. We sensitize sniper students to their presence by posting crepe paper streamers every 100 yards on our 1,000-yard known-distance range. They're initially surprised to find that winds at the distant firing line are steady and left to right, while mid-range winds are gusting and right to left.

It's only by looking closely that they notice the firing line overlooks an expanse of flat, open ground—which causes the steady wind— while there's a service road that cuts through thick woods at mid-range—hence an opposite, gusty wind.

Your challenge as a sniper is to learn where to look to detect evidence of winds so that you can determine exacdy the directions of any winds in your sector. Having determined direction, you then must estimate wind speed, which equally demands attention to minute details.

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