Advanced Marksmanship Wind Drift Discussion

gvanhyning

gvanhyning

Sergeant
Full Member
Minuteman
Mar 14, 2009
386
1
Republic of Texas
www.roguefirearmscoating.com
#1
I'd like to get everyone's input regarding calculated wind drift and the most accurate dope. I have been using JBM for ballistic calculations and have my bullet drop calculations verified. However, I have been using 10 MPH wind from 090 for wind drift output in Mils for reticle holds. Here's my question: Do you get more accurate wind drift using 1 MPH wind from 090 and then use that as a multiplier times the wind speed? I realize there are value factors for wind direction that need to be considered as well. Would appreciate your insight and comments.
 
#2
Re: Wind Drift Discussion

the most accurate dope is that which you the shooter records in a logbook for future reference....and actual glass and trigger time in many and varied conditions to include square box ranges, ukd senerio and open range set-ups.....


lots of different stuff can happen like dog-leg x-wind and up draft,,,,,trigger and glass time along with a log, just go do it
 
#3
Re: Wind Drift Discussion

Ballistic programs are very accurate for doing the math. But actually reading the wind, especially in real time, is probably the biggest variable in long range shooting. Doing that takes experience. There is no substitute for doing it. When you do it I think you will find that you need to hold less wind than you think you do.
 
#4
Re: Wind Drift Discussion

I have started shooting some timed events and worked hard verifying my bullet drop data. I have cards built to tie on the scope that references MOA bullet drop and Mil hold for 10 MPH at 090. I thought I might streamline the process and reference all wind at 1 MPH and multiply by actual or estimated wind speed then figure wind value if it's not 090 or 270.
 
#5
Re: Wind Drift Discussion

Stop trying to call wind from a card. If you feel the need to use math to call wind, search for the rule of nines.
You should use something simple like that until you just look at your environment and feel like you can take a stab at it without Using a formula.
I say all of this, assuming that you are holding for wind and not dialing.
Wind flows through your environment like water, but unlike water you can't really see it. You can get pretty good guessing what it's doing, but I would stress that it's always a guess. You should be ready to follow up that guess with a second round. That first one is just to confirm or deny your initial guess, but the second shot needs to be sent quick.
Shoot more is the best answer. Nothing can replace that. I would forget the cards for drift.
 
#6
Re: Wind Drift Discussion

Thanks for your input. I'm not trying to call wind from a card but have on hand a quick reference that is as accurate as I can make it. I have one shot at each target and just want to increase my chances of a hit that first shot. I know shooting more is going to improve my skills and keeping a log but I'm just trying to make a best guess a little bit less of a guess.
 
#7
Re: Wind Drift Discussion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gvanhyning</div><div class="ubbcode-body">Thanks for your input. I'm not trying to call wind from a card but have on hand a quick reference that is as accurate as I can make it. I have one shot at each target and just want to increase my chances of a hit that first shot. I know shooting more is going to improve my skills and keeping a log but I'm just trying to make a best guess a little bit less of a guess.</div></div>

First, listen to what Graham and Boltripper said, cause you're going about what you want to do backwards. If you're going to charts, graphs, cards, and IPhone while on the range you're not ready to shoot in wind yet. However, with a good grasp of what wind looks like, along with knowledge of how to counter for it, this is stuff you can get from the classroom, you won't need any props to get good hits.

Now, without looking at or referring to anything, how would you favor for a 10 mph full value cross wind at nid range for a good hit at 600 yards using a wind constant of 10?

You should get the answer in less than a heartbeat, if you can't your pretty much screwed for a multitude of reasons.


 
#8
Re: Wind Drift Discussion

Greg, you are welcome to do whatever you want, but start out by answering your own question by using the tool you have at your disposal - JBM. Run it at 1 MPH, then 10 MPH, then multiply the first number by 10 and see if they match.

Even if this does work for you, you will be swimming against the tide on how the people I know locally communicate about the wind. Everyone I shoot with as well as help out in this arena have their cards set up with 10 MPH 90 degree/3 o'clock wind data as their baseline.

A 90 degree full value, fraction of, or multiplier of greater than 1, is a way of communicating that is independent of what chambering, bullet, velocity, etc. you are running.

If I come off a shot and say "I held half value left" while shooting a 168 running 2500 FPS, then you lay down on the same target with a 7 WSM running a 180 Berger at 3000 FPS, my feedback to you is still valid as your table tells you what full value is for your rig. Assuming the wind is fairly constant, hold off half the value on your table and you'll be on the money, even though I may have held off a full mil and you only a half mil.

Good luck getting this sorted out.

EDIT TO ADD: this approach is also unit independent. A half value is a half value whether you are running mil or MOA. Go to your 10 MPH/90 chart, cut the number in half, and you have your hold or dial value.
 
#9
Re: Wind Drift Discussion

Imagine wind drift as being like gravity; acting sideways, and imparting a sideways acceleration due to a force just the way gravity does.

Now add to that the facts that unlike gravity, the force is not a constant, and more, that it can change magnitude and direction across the duration of flight.

Ballistic calcs are ill-suited to deliver absolute solutions, due to uncertainties in the constancy of the wind force, and in the ability to read and input those inconsistencies.

If you really want to visualize the effect of varying winds forces and directions, imagine a bowling ball running down the lane while someone keeps tilting that lane to left and right. And yes, the ball has some "English", too...

Breaking the trajectory into segments that correspond to different wind zones could be a better approach, but practical limits immediately act contrary to success because calcs almost invariably fail to deliver a solution before the conditions have changed significantly.

Which leaves is with the "_9H approach"; which is the most practical one I can see here.

Greg
 
#10
Re: Wind Drift Discussion

It's not my approach; nothing original about it. I'm a copycat of something that works for a lot of people.

Not a great deal of need for imagination either; the wind moves the bullet sideways. Pretty easy concept to understand IMO.

"Wind Zones" is a given, but the net effect is still a single thing. The original question was about how to represent/scale wind, not how to read it.
 
#14
Re: Wind Drift Discussion

It is not just trigger time. If you can not do the math as Sterling Shooter stated, then you can be real accurate to within .5 mph and still miss. If it takes you too long to figure out the required hold then the wind will change. That is the only constant in wind, that it will change.

You can use rules of 9, rules of 10, BC rules, whatever floats your boat, but learn how to convert it to a hold. Rule of 10 is easy, it is a moa hold and equates to a constant that is used to compute moa adjustments. range in hundreds times wind speed divided by 10. It works reasonably well for .308 in the 168 to 175 gr at 2600 fps. What is nice is that this means that 10 mph wind produces a moa hold that is the rnage in hundreds. Example Sterling Shooters question 10 mph at 600 is 6 moa. Hold for mils is 1.74.

Rule of 9s, range in hundreds times wind equlas 60 and every 9 is .25 mils. 9, 18, 27, 36, 45, 54, 63, bingo, between 54 and 63 so a heavy 1.5 or 1.75. Your call. But you have to be able to do this by looking and knowing the wind speed equals that amount.

Another is BC in which the BC for the .308 is about .4xx so use every 4 mph and figure 100 equals .1 mil, 200 equals .2 mil, 300 equals . 3 mil, etc. Thus 10 at 600 at 10 mph equals 1.2 plus .3 or 1.5 mils. The difference in the three wind calls is because each is a guide and gets you in the ball park and your shooting expereince with your weapon and ammo will then get you on target. The difference is also less than 1 moa.

Find the one you can do fast and accurately and you will not need a card.

My 2 cents, sorry for the length of the post.
 
#15
Re: Wind Drift Discussion

I shoot a few rifles that have different ballistics so I do use JBM as a quick reference for a full value 10 mph wind. Then I fill in the blanks with shooting data compiled while I shoot. It is helpful for me as a reference. For example I shot one rifle this weekend that needed 1.2 mils while another needed 1.8 mils full value, 10 mph at 700 yds. Knowing full value for 10 mph for each rifle let me adjust my mental math for dope in the conditions I was practicing reading. I use it as a quick reference....all the rest comes from field observation and recorded data. I go between hero and loser based on my wind calls but every experience is a building block.
 
#17
Re: Wind Drift Discussion

Great information, very well put, I will be playing with this in my log book, one thing about the Las Vegas desert, we don't have a problem finding a good windy day to go shooting...I see lots of "test days" in my future!
 
#18
Re: Wind Drift Discussion

gvan, a more experienced shooter once suggested to me shoot F-Class for wind training. He was right.

Some of my friends avoid the range on windy days like rainy days. Windy days are when I wanna shoot.
 
#19
Re: Wind Drift Discussion

I agree Casey. I have been shooting the Sporting Rifle Match in Raton, NM and last Sunday convinced me I need to work with more focus on developing wind skills. I have the guns and basic marksman skills but the wind has been my downfall. I am going to get into some F class matches, as many as possible. Wish I knew some shooters in my area. The people I currently know run their mouths a lot but can't or don't want to do anything. Thanks for your input.
 
#20
Re: Wind Drift Discussion

i think i uderstand your question so as far as a starting point for your wind data i think 10mph is best. even if you only encounter 2-3 mph normally. this is because the numbers arent big enough to show the change from one range to the next if you use 1mph. it would be like this...
100-300yds .1 mill 300-500 .2 mills... those arent actual numbers but the point is theres not enough to show the slight change from one range to the next. so if you multiply .1 by 3 for your full value 3mph wind and its actually more like .05 for 1mph instead of the .1 you have down then your way off and this will get worse with larger numbers.
 
#21
Re: Wind Drift Discussion

gvan, Here's what I do about that mouth runnin: carry around a coupla welding rods in your truck and next time your at the coffe shop around those guys talking big about all their guns back home in the gun safe, hand em a welding rod so they can weld up the barrels ince they aren't going to the shoot them, they may as well make them safe for the kids to play with.

Or give them a ziploc bag so they can put their firing pins in and return them to you since they don't need them... you might be able to use them for punches around the shop.
wink.gif


edit: leave their sorry asses at the house and go to a match without them. They'll just be a drag anyway.
 
#22
Re: Wind Drift Discussion

I'm assuming the Raton events use the Tubb Range. I got to shoot there in 2002, and the large number of winds flags we had then made understanding how wind propagates across the intervening area much easier to do.

I came away with a better understanding of how solid wind disclosing media can make folks better distance shooters.

In the interim, I've been puzzling about why I've never shot as well since. Thinking about that and typing the above comments, I think I may have finally arrived as a believable reason.

Even in our local FV200 events, I try to stick a few poles with surveyor tape streamers alongside the shooting lanes. It helps, but not anywhere close to what we had at Raton.

Greg
 
#24
Re: Wind Drift Discussion

The Sporting Rifle Match is held in a canyon across the ridge from where the Whittington Center facilities are located. The shot impact area is into that ridge so you are walking a two mile course with gun and gear engaging steel targets at each shooting station. The terrain and canyon make for some tricky winds. I am quickly learning to watch all the other shooters impacts to pick up wind direction and velocity as there is not always another good indicator out there. Sure there are trees and grass but they don't always show what the dust will. You can pretty much shoot prone at all positions. Check the link that _9h posted. It's a great event with a lot of good people. Wish there were more events like this one.
 
#26
Re: Wind Drift Discussion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gvanhyning</div><div class="ubbcode-body">I am quickly learning to watch all the other shooters impacts to pick up wind direction and velocity </div></div>

I can sometimes see that the shooter in front of me is hitting left / center / right on the target.

But I don't know how much they are compensating for the wind.

And the wind frequently changes between shooters.
 
#28
Re: Wind Drift Discussion

True statement Zak. At position 3 (I think it was 3) on Sunday I missed holding right edge on the first two, corrected on three and missed in the direction of the correction. The winds at position 2, 3, and 4 seemed to change with each shot and with the ground being wet it was hard to see impact on a miss.
 
#29
Re: Wind Drift Discussion

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gvanhyning</div><div class="ubbcode-body">I'd love to do that Casey but I've found it's better to just keep my mouth shut. Sooner or later the sidewalk commando's will have to put up or shut up and it's been my experience that most just shut up.</div></div>

That's what I should do more of
 
#30
Re: Wind Drift Discussion

No, and I stand corrected. Your matches are a different experience than I was envisioning. My experience was centered on the F Class segment of the 2002 Spirit of America Match.

Greg
 
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