Looks like these post kinda get mixed up as to the order they were posted in. Wynne I will try and see if I can get you an answer or two on this wind reading thing. Please bear in mind that I am also a “Student” of this wind reading thing, I know just enough to get myself into trouble some of the time but it is a start.
So the question is when to wait and when to shoot. This can be a long journey around the barn but here are some basic’s. Once again please take into account this is after all just my opinion, ask another guy and you just may get another answer. Sometimes both opinions may be wrong. One of the first things you need to do is start from the beginning. You must have a “TRUE WIND ZERO” on your scope. Without that you have no place to start. This can be a trying thing to do by the way. Best bet is get to the range just as early one day as you can, right as the sun is coming up is when the wind is at it stillest. It doesn’t matter which yardage you shoot at but I like 200 or 300 yards for this. I also use a large target backer and no target. Just mark a aiming point somewhere close to center, the size of a quarter is about right. Now if there is truly “NO WIND” get set up and fire your first two shots into the berm, this is to foul the bore and put a little heat into the barrel. Then shoot at your aiming point and adjust the scope to dead center. Once you have this sight setting set your scope turrets to ZERO, and this will be your true wind zero. All corrections in windage from now on will be based from this True Zero.
While you are there and set up you also should be sure that your scope is tracking correctly. This is a good time to do this as there is NO WIND–Right? To check how the scope is tracking you will need to “Shoot The Box” Adjust your windage knob and put in 5 minutes of left wind. Now while using the exact same “AIMING POINT” that is your quarter sized spot, Fire one shot, now leave the windage alone and come up in elevation 5 minutes, once again fire one shot. Now dial in 5 minutes of “RIGHT” windage, fire one shot this should also return the turret to Zero. Now come down in elevation 5 minutes and fire one more shot, this last shot should be on the aiming dot. When you go down range to check this target it should be one neat little box with every shot spaced 5 minutes apart. If this is the way it is then you know you have a true wind zero and also a straight tracking scope.
Now to your question about that day in the bottoms with all of that stuff going on. There is no one thing to read to get your indicators for what the wind is doing. One great tool we have is the “Mirage” it is such a good indicator because it has no mass. Think about it this way, the wind flags on any range weigh something. As the wind is changing or in a change the Mass of the flag has to be put into movement by the wind itself, this takes a little bit of time to show us the shooters that the change is happening or has happened. Mirage on the other hand has no MASS and it weighs nothing thus it shows a change almost in an instant with no lag time. The flags once they show a change will lie to you, the change could be done by the time they show the first indication of that change. That is why you never ever want to shoot a limp flag that is just hanging there. A change may have already happened and the flag just has not caught up yet. Now mirage can lie to you as well it’s just harder for it to do that as it is not a very good liar. The time you really have to worry about the Mirage is when it is in a boil and looks like it is just setting there. Also Mirage is only good up until 12 mph after that it is still there but it has flat lined so bad that no one can see it, no matter who they are.
I use the flags for the sole purpose of determining WIND DIRECTION, and do not rely on them for velocity I try and judge the wind speed off of the mirage. OK so which mirage you ask? Do you mean there is more than one? As you are looking down range there is mirage at each yardage and unless the wind is steady all up and down the range they all will be different. So here is my take on this. I want to judge my shot by the most important Mirage, that is not what you see “AT” the target remember the bullet is at the end of its flight by the time it gets there. I chose a distance for the mirage about two thirds of the way down range, and try my best to let it call my corrections for me.
So when to hold? I personally will never shoot a boil in the mirage if at all possible sometimes time may force you to shoot however. I also will never shoot a slack or limp flag especially if the flags have been active for the day. if the flag is hanging then you are in a wind change in all probability. There is much more to this than I have tried to explain but for this time this will have to do.
The most important thing you can do is shoot as much as possible and in the wind and with wind flags, and they should be the same ones as will be there in a match. Different flags react in difference ways, that’s another reason to be leery of those critters.
A very enlightening day can be had on the range with this little trick I learned in the Corps at Recon School. Get you a couple of 5 lb coffee cans, also buy you some smoke bombs when you can find fireworks for sale. I am sure you guys know the kind I am talking about it is a little black pellet looking thing. Set one in that coffee can and light her up. Scatter a few of these in difference places on the range. That black smoke will give you one of the best lessons on the wind you could ever imagine.