Challenges of "wind"... how far does it start making a difference ???

M

Magnum Wheel Man

New member
I'm still sighting in some of my rifles, that I changed out scopes on over the winter... MRS was out of town Sunday, so I took advantage of the day, between rain showers, & took a couple rifles out to at least get them on paper at 100 yards... I started at 50 yards, got them sighted, & then moved to 100 yards off sand bags on my bench... only thing was, it was quite windy, going from ( my best guess ) 5mph to over 20 mph, quartering across my range...

after initial sight in, I had 4 rounds left for each rifle, & tried to shoot a "group" in the wind... admittedly I usually don't "choose" to shoot targets when it's windy, but thought I'd give it a try...

1st rifle was a Ruger 77 in .243, 2nd rifle was a custom 95 Mauser in 7 X 57...

on both of my rifles, I had really 2 groups of 2 shots nearly touching... 2 shots nearly touching, about 2" away from the other group of 2 shots nearly touching... all 4 shots were within 1" vertically, but were over an inch apart horizontally... both rifles were shot with some factory ammo I was using up, so I wasn't testing my reloads... 100 grain bullets in the .243, & 140 grain bullets in the 7mm

so... 20 mph + gusts open up my group an extra inch at 100 yards in those calibers ??? or was it me, perhaps trying to compensate for the gusts ???

I expect it was a shooter error, but don't know if 20+ mph gusts can physically open a group by an inch at 100 yards on a .243 or 7 X 57 ???

your thoughts ???
 
This is actually for 147 Gr .308, but its a good indication of how wind speed (@ 90 degrees) & distance effect bullet path horizontally. The "clicks" referred to are metric increments of 1cm & 100 Meters, roughly 1/2" or 1/2 MOA.
Code: 
WIND	5	10	15	20
50	0	0	-1	-1
100	0	-1	-1	-1
150	0	-1	-1	-1
200	0	0	-1	-1
250	0	0	0	0
300	0	1	1	1
350	1	2	2	3
400	1	3	4	6
450	2	4	7	9
500	3	6	9	12
550	4	8	13	17
600	5	11	16	22
 
Wogpotter, does your table mean that ammo has zero wind drift if sighted in at 250 yards?

It's confusing to me. Looks like bullet drop data above and below the line of sight.
 
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thanks for the replies guys... so before I use the link BART posted, sounds like at least 1/2 that space in the "group" could actually be wind related...

I can't even imagine how tough it would be, right now, to shoot actual long distances on a windy day, or pull off that "one" shot sniper hit, if there was more than a breeze...

hoping to play more in the future out to the 300 yard limit of my range, on windy days & learn to be more patient ( I allow time for my light weight .243 barrel to cool, but pretty much just shot through whatever wind was blowing )... I did not expect much drift at 100 yards with those 2 calibers...

I am keeping a shooters note book, for each rifle, so hopefully I can casually learn as I go out, better, what to expect
 
Long range becomes a challenge because i 1000 yds there may be three difference wind direction and velocity !:eek:
 
BART... thanks for that link... I entered the data as best I could ( Remington doesn't list their ballistic coefficient on either their ammo or their bullets on Midway's site, so I pulled data from a similar bullet shape, & used Remington's velocity)

looks like 2 MOA wind drift at 100 yards, on the .243 at a peak of 25 mph, at a 45* wind angle ( much more than I expected )

looks like 1.5 MOA wind drift at 100 yards on the 7 X 57 at a peak of 25 mph as above

I printed up a cheat sheet for that rifle, & will likely do the same for each that I shoot... I know it'll only be a guide, but will transfer the data inside the cover for each rifles book...
 
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just as a general question, when do you guys pull the trigger... a lull in the wind, in what you perceive as at the middle ( average wind gust ) , or only when it's at it's peak ???

in other words, ( & I assume it's best to shoot when there is the least wind ) what is the best way to minimize the groups effect by the wind ( talking group size, not necessarily group placement )

In the past, I only went out on nice calm days, however in order to challenge myself, & learn more, I'd like to shoot on not only breezy days, but also on pretty windy days... guessing that 17 Fireball is even more challenging on windy days :o
 
Bart's the one to go into detail on that, but what I have seen and done, the usual approach is to gauge the wind and shoot during the prevailing conditions. Better to make all your shots whilst it is blowing 10mph left to right than to get caught by a change in speed or direction. Wait out a brief change to 5 mph.
Shooters will avoid the "boil," too. In a calm, the mirage moves upward, it is pretty much heat waves, after all, and will displace the image of the target, causing vertical spread.
 
The best way to "read" the wind is focus a spotting scope about 2/3 the way to the target so the heat waves, mirage, can easily be seen wrinkling across the field of view. Look as those that are above the line of sight up to the highest trajectory point the bullet will go through.

A given cross wind speed has the greatest effect closest to the firing line. That same wind close to the target has little effect, but it's still there. Winds midrange have a medium effect. Cross winds are also faster above the line of sight. Depending on the terrain, a wind blowing 5 mph in the line of sight can be blowing 7 mph 3 feet above the line of sight for a 600 yard zero. For a 1000 yard zero, the wind at the maximum ordinate of about 11 feet will be a lot faster than in the line of sight. The more obstructions to wind on the terrain (rocks, boulders, trees, hills, etc,) the faster winds aloft are compared to the line of sight a few feet above the ground.

Winds a 3 and 9 o'clock have full value. If from 2, 4, 8 or 10 o'clock, they have 9/10ths value (.866, acually). From 1:30, 4:30 7:30 and 10:30, the effect is 7/10ths value. At 1, 5, 7, and 11 o'clock, they have 1/2 value. A 10 mph wind from 4 o'clock moves the bullet sidways about the same as a 9 mph wind at 3 o'clock.
 
Wogpotter, does your table mean that ammo has zero wind drift if sighted in at 250 yards?
Click to expand...
If sighted in at 250 it does indeed have zero drift at that distance, at least until the wind changes.:)

It was copied from an Excel sheet so to differentiate between L & R displacement I used negative or positive for alternate side shifts.
 
I find that early morning/late evening shoots offer the best chance for the least amount of wind. It takes time for an early morning wind, to work itself down {around 10 am} to lower ground surface elevations.

Pattern the wind before you shoot. The wind usually comes in waves --- each around 5 to 7 minutes long --- so I would want to shoot in a building wind or one that has maxed out.

A lull in the wind...means a possible change in wind direction, so that would be a bad time to shoot. Try to shoot with all the wind flags flying in the same direction.

Check out one of David Tubb's books, who has a chapter on shooting in the wind. Google: David Tubb "Wind Reading for Hi-Power Shooting", and other related YouTube videos.

Buy a good wind meter {I highly recommend one of the Kestrel units}, so you can memorize wind speed values. I do use wind flags --- I prefer using 4' high fiberglass curb locator posts, that you can buy at a local hardware store. I stick a 7.62x54R empty shell casing on top of the pole, and solder or tape a surveyor's thin 1.5' long wire flag; on top of the shell casing. Remove most of the plastic flag at one end of the wire, and bend a wire loop on the other end, so you can attach an approx. 2.5' long plastic yellow caution tape.
 
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Got a 'droid?

Download Strelok....free, and will tell you most everything you need to know...

Except what the wind is doing 30' off the ground...halfway to the target....etc. etc...

As you can see, a stiff breeze will push a bullet at even short ranges. The computer program will nail it pretty closely IF the wind is consistent in speed and direction, and you know your MV and the rest of the required parameters.

As a rule, if we're doing anything "important"- as in load development, or sighting in optics, we just stay home unless conditions are near ideal.

There is enough variation in shooter error alone, that we don't want mother nature to be a factor.
 
280 Ackley, 150 grain Accubond LR, 20 mph crosswind...thats a high BC bullet (.295 G7 according to Litz)....courtesy of the Applied Ballistics app (worth every penny)...wind makes a difference pretty much immediately, and gets worse the farther you go...this data also includes spin drift, but thats minimal compared to the wind drift.

 
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