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Basic Wind Reading for the Rifle Shooter
Disclaimer: This is not law, this is just what I found when trying to shoot better at 600 yards. I spent a lot of time reading and there is way more informing my practice than the below but we often hear guys on the line saying "I just need to learn to read wind." and most of what I learned when I was saying that wasn't really useful to me until I figured out the below.
This article is for the Service Rifle Shooter, Midrange/Longrange Shooter, and F-Class/FTR shooter. Herein is an attempt at discussing the first steps of wind reading at midrange and beyond. By no means is this a complete discussion of the dynamics of wind reading, in fact it is specifically limited in scope. This limited scope includes what, for me, was essential information and contrary to most of what I had encountered as a “new shooter”. Shooters who have researched this topic before will notice that a number of topics are NOT covered in this document. If you read/watch content related to wind reading you will find that the VAST majority of this information is focused on estimating a value of wind for an observed condition. For 90% of shooters, even competition shooters this skill is not only difficult but completely unnecessary.
Prerequisites:
A confident zero: It is practically impossible to learn what the wind is doing without a confident full range zero. This is especially important with iron sights where sight tracking can move shots laterally as elevation is added. Linked here is a method to establish a confident no wind zero at any range, all while working on a 100 yard range.
A confident hold: It is common to see new shooters shooing poorly at full range and complaining about not knowing how to read wind. Quite often the greater problem is one of holding than an inability to read the wind. Every new shooter should work towards being CONFIDENT that a 20 round string of fire at a suitable reduced range and target (200 yards or 100 yards) will always score 194 or above. Without this confidence or ability learning to read wind at the full range will be problematic. The good news is that early on, learning to hold a 194 or above at reduced range will net much higher scores much faster than learning anything about wind other than what direction it is coming from. If there is one major takeaway from this article it should be that you MUST be shooting 194 or above at reduced range to learn how to read wind.
Shooting in the Wind:
The Call and Check process: A knowledge of what the wind is doing can only come from observation of its results. The process of estimating a wind value, firing a shot and observing the shot value will prove or disprove the original estimate. The shot process therefore begins with a wind call, the shot is taken and after proper follow through conditions are checked. If the conditions are the same then the call matches the check and the shot value (if a center 10 was properly shot, look at prerequisites) will inform any needed adjustments to the original call. If the check does not match the call then the shot value will inform the difference between the value of the call and the value of the new condition (as long as there can be confidence in the original call).
This is the standard process that will allow each shot to add information to the shot process rather than let the shooter slip further into unknown territory.
A brief illustration of the above:
Shot 1
CALL: A constant full value wind from the left is blowing at a suspected 16mph across the full 600 yards (from targets to firing line). 4.25MOA is put on the sights and the shot is taken (normal follow through and position checks confirm a center 10 shot can be expected). Instantly the conditions are CHECKED and the conditions match the CALL. The target comes up as a waterline 9 at 9 o‘clock, mid-ring. The CALL and the CHECK matched, and the shot was called center so our new estimation is that the condition is worth ~3MOA not 4.25MOA. All subsequent CALLS will be based on the fact that this condition is worth ~3MOA left. At this point, why the condition is worth less than expected is not important.
Shot 2
CALL: The previous wind stayed constant but let off, the estimate is half its previous value. 1.5MOA is taken off the sights leaving 1.5MOA left on the rifle. The shot is taken and called good center. Conditions are CHECKED and conditions have changed from the CALL; wind has fallen even further to the quietest they have been all day. The target comes up as a waterline 9 at 9o’clock tight to the 10 ring. Knowing the previous information a confident estimate can be made that if the wind goes no lower than this current condition and peaks with the previous condition the range of the wind should be from 1MOA left to 3MOA left. Every future wind can be compared to this range and a quality estimate can be made. This is commonly called bracketing the wind.
Ignoring the Corners: Shots lost to elevation and corners are an indication of poor sight focus and poor position not wind. No shots above the top of the 9 ring or below the 9 ring will be considered valid data. Corner shots are particularly suspect and are not to be considered valid data. There are ranges and conditions where wind will create elevation shifts, that is not within the scope of this article.
Focusing on the bigger change: Wind has two components, direction and velocity. Typically only one of the components will change drastically while the other will fluctuate only slightly. Watch the wind during your scoring duties and during any time you have sitting on the range. Notice which shift seems more severe and mentally log it. When you get to the line and you are making adjustments to the sights based on a change, take into account the component that is shifting more drastically.
Be Patient: If the wind is slow enough that there is mirage do not shoot when the mirage changes from a direction to a boil. Similarly be patient with big let-offs and switches, wait for them to settle into their new orientation before taking a shot. Transition periods are turbulent and getting good data during turbulent periods is hard. The time to shoot fast is when the wind is consistent and previous observations suggest that it will stay that way or build. Let-offs happen faster and stronger than builds, it takes energy to move wind so when that energy is gone it goes fast.
What is the value: Herein is a warning. The load shot at 600 yards is a known quantity, it has a known muzzle velocity and it incorporates a known bullet. There are excellent tools on the web (JBM ballistics for one) that will calculate wind drift and drop tables for specific loads. Do not rely on a generic chart when custom ballistic tables are available. Additionally even a custom table will only give data for a specific constant wind value across the whole range from shooter to target. This condition is rarer than a day with no wind at all and therefore only use a chart or table as a device for transposing wind value from known data, by using the CALL & CHECK method above.
Using range flags correctly: Page 38 of The Wind Book For Rifle Shooters† gives a particularly good account of the use of range flags for reading wind, a short synopsis follows. At least two flags must be used to properly observe wind on a range.
Fg1 and Fg2 depicts how two flags are used to read the wind. Fg2 is a copy of the one found in The Wind Book For Rifle Shooters. Notice how it is very easy to see the velocity difference between the two left flags in Fg1, and very easy to see the direction difference in the right two flags of Fg1. One flag can display either velocity or direction but never both without the shooter being in two places at once.
For example, the left most flag in Fg1 is pointing at the top of the flag further downrange. It is very easy to see this flag point above or below the top of the downrange flag making it a clear indicator of a wind speed change. The downrange right flag is similarly pointing to the right of it's pole and at the middle of a particularly pointy tree, if this flag switches to being inline with the pole or left of the pole like it's uprange partner then it is marking a clear change in direction.
† Miller, Linda K., and Cunningham, Keith Captain The Wind Book For Rifle Shooters Paladin Press 2007
A good hold is worth 1 MOA: Many people have heard this but analyzing the math shows us it's truth. If shooter A holds 1MOA then a 2MOA wind shift will push shots from the edge of the 9 ring to the edge of the 9 ring (if he doesn't touch the sights), thinking that he "cannot read wind". Alternatively if shooter B holds 1/2MOA then a 2MOA wind will only push his hots out of the 10 ring at the biggest extremes. Shooter B doesn't touch the sights, constantly nets 10s and spends the vast majority of time on the line observing the conditions and shooting confidently. Shooter A shoots a 9, puts some wind on the sights and gets another 9 out the other side because his hold is large and he's spending too much time thinking about the sights and struggling in the wind.
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