Vertical Drift with full value winds at 3 and 9 o`clock with strong winds?

[Bowman26]

I've got a question for you bench jockeys that have more experience shooting long range in the wind than I do. From my research it seems that the accepted rule is that with the wind from 9 o`clock and a right hand twist that the bullet will drop below centerline as it is being pushed to the right. Likewise it will climb above centerline in a wind from 3 o`clock as it drifts left.

My question is at what ranges and by what amount of vertical drift have you seen for given wind speeds at full value? I only shoot out to 600 yards but I have heard of this happening with .22LR at closer ranges. So what do you guys think? What have you witnessed and found to be the case with the 6 & 6.5mm bullets from say a couple hundred yards to 1000+? Does it only affect shots out past a certain distance with any real movement or is it noticable even at shorter range if the wind is significant enough?

Thanks,

Bo

 

[KMart]

I hope this works

 

[Keith Glasscock]

There is a term for the phenomenon. It is called Aerodynamic Jump.

Bryan Litz's book explains the cause well and includes a simple calculation for estimating the approximate deflection.

Hope this helps,

 

[Benjerman08]

K,
Would you be so kind as to explain how the chart works. thanks

 

[KMart]

Ben

The outside numbers are the wind direction...1 through 12 o'clock. You match that number with the location inside the ring and that is the location that the wind will influence the shot to go. Light wind less effect. Faster wind more effect.

At least that was the way it was explained to me. Reading the wind is harder than Chineese arithmetic to me.

 

[Bowman26]

Yes I have seen several different charts and diagrams trying to illustrate what is happening. I understand the physics behind it and the aerodynamic principles at work that cause it to happen.

What those charts don't give you any idea of is how much up and down dispersion is created by a given wind speed from each direction. Perhaps the reference to Litz's book is the answer if he has devised some base calculation on how to determine a possible deflection solution.

I only shoot silhouette and I have just been curious if this little bit of ballistics information even makes a hill of beans when shooting steel animals offhand. IE if someone shooting 600y Benchrest only seems an inch or so of vertical stringing with a 6.5x47L in a 10-12 mph wind from 3 & 9 O'Clock at 600y and maybe 2" plus with say 15-20 mph? If this is all the movement we are talking about it amounts to a minimal amount of concern for me shooting silhouette with very little input of holdoff required to account for it. Unlike those trying to put one hole in paper with 5 shot groups or into the X Ring where an inch or so of movement could be a killer.

Bo

 

[Alex Wheeler]

I have seen the proverbial ''wind report'' in short range br targets. But I do not see this in long range br. Are the long high bc bullets less effected?

 

[M14AMU]

Right raises, left lowers is the rule! Very noticeable if you've ever shot .22 competition outdoors like the old Dewar Course of fire! Very noticeable at 200 yd. outdoor competition with the same caliber! Dewar Course competition was highly popular 50 years ago! Like everything else in America of old...it's gone the way of the wild goose...sad to say!!