Target Sports

TARGET RIFLE BASICS: WINDS OF CHANGE

Created on 14th May 2009

CHRIS WHITE advises that making allowances for wind can improve your score - but experience is key to becoming an effective wind reader

Any experienced Target Rifle shooter will realise that in most cases matches are won or lost not merely by one's ability (or lack of it) to shoot straight but also by one's skill (or lack of) at making the appropriate correction for wind. In common with most of this series this is not a topic we can deal with in a linear manner so it will be as well to read the articles in sequence and then come back to this one and re-read them.

One thing we need to nail right from the start is that no amount of reading or teaching will make you (or me) an effective wind reader. Whatever wind reading ability I have developed has come from over 35 years of experience. During that period I have shot over 60,000 competitive shots on 32 ranges in eight countries. This means that I do not often encounter conditions that I haven't seen sometime and somewhere before.

Where this is leading is that what I can do in this series is introduce some concepts that will help you to understand wind reading; what happens next is up to you. If you want to develop your skills in this area then you must put in as much range time as possible on as many different ranges as possible shooting good ammunition through a good rifle. The harder you work the luckier you will get.

There are three principal methods of reading (or guessing) the appropriate wind correction. These are: flag reading, mirage reading and the scientific wild donkey guess. The success or otherwise of the latter depends on the experience, wisdom and often low cunning of the appropriate donkey!

‘How to shoot' books and coaching courses will major heavily on the first method which is fine if you spend your time shooting at Bisley but not a lot of help when you are laid on a pile of sheep droppings on some windswept old volunteer range somewhere in the Pennines where the only flag in sight is a well-shredded one half a mile behind the range! Nevertheless we have to start somewhere and flag indications are the easiest of our wind judging concepts to understand. The other two methods depend on differing ways of interpreting these concepts so whether you have or have not the benefit of shooting on a range bedecked with windflags you need to understand the basics. So read on!

How much a cross-wind of a given velocity deflects a bullet at a given distance depends on the time of flight of the bullet from muzzle to target. That time of flight depends on various factors which we do not need to go into.

Given that we are dealing with NRA Target Rifle most of us will be shooting ‘Palma Match' type ammunition. So at every distance we shoot, a cross-wind of, say, 15mph will produce a given deflection. Since our sights and our score books are graduated in minutes and, by now, so should be our brains we think of this deflection in terms of minutes. For example our 15mph cross-wind may require two minutes at 300yd and 12 minutes at 1,000yd. However, if we are shooting .223 or .303 these values will be different. In the case of a .303, for example, these values may be three and 14½ minutes.

While there may be variations in time of flight between ammunition brands at this stage, we can for all practical purposes ignore them. Our 15mph wind will require the same correction every time.

Using windflags

Now that we have got that out of the way, let's forget about absolute wind velocity since our brains need to recognise this as a two minute wind at 300yd. In this instance the windflag will be flying straight out from the pole. The mid-line of the flag will be horizontal with the ground. If the wind strength increases the flag will ‘loft' - it will rise above the horizontal. If the wind strength decreases the flag will fall towards the pole.

We know instinctively, without needing to go into the physics of it that the harder the wind blows the more it will deflect our bullet and the lighter it blows the less it will deflect the bullet.

Let's look at how we can interpret this by looking at our windflags. If the flag has risen above the horizontal by 10° then our cross-wind at 300yd will require 2¾ minutes and if it rises to 25° it will require 3½ minutes. If the flag falls so that its mid-line is 20° below the horizontal the deflection required will have dropped to 1¾ minutes. If the flag drops to the point where its mid-line is 45° below the horizontal it will only require ¾ minute of correction.

These angles may seem a little anomalous but they represent flag conditions which are easy(ish) to recognise. They look like figure one. This is the beginner's ‘starter for ten'. Getting down at 300yd and looking at the windflags you should be able to recognise something which approximates to one of these flag attitudes. You make your judgement and fire your sighters and then evaluate the accuracy of that judgement before you fire your first to count.

At 300yd you should very rapidly develop the ability to get within ¾ of a minute of the actual wind, in reasonably stable cross-wind conditions. That is good enough, if you are grouping tightly enough, to score a bull.

The further away from the target you are the longer the bullet is in the air and the greater will be the deflection caused by a wind of a given strength. These deflections for cross-winds and ‘Palma' type ammunition are shown in figure two. Remember the same strength of cross-wind, at a given range, will deflect the bullet the same amount whether it's blowing at Bisley or Timbuktu. What you need to do is determine what that strength is and, as I said, this is your ‘starter for ten'. Of course the wind does not always blow straight across the range and what causes the deflection of the bullet is the wind vector. That is the combined effect of wind strength and wind angle in relation to the bullet's flight. We will come to this next. At this stage however it is important to be able to recognise these five basic flag positions.

TARGET RIFLE BASICS: WINDS OF CHANGE

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TARGET RIFLE BASICS: WINDS OF CHANGE

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