Possibly the most
misunderstood and difficult techniques to master when rifle shooting,
be that stalking, foxing or vermin control is judging the wind
conditions. Reading the wind correctly is critical for placing your
bullet exactly where you aim it, especially when a humane shot is
desired.
Introduction
Possibly the most
misunderstood and difficult techniques to master when rifle shooting,
be that stalking, foxing or vermin control is judging the wind
conditions. Reading the wind correctly is critical for placing your
bullet exactly where you aim it, especially when a humane shot is
desired.
Wind conditions are never
the same even when shooting from the same position and can play havoc
when you need to connect with that hard stalked stag on the hill and
you are faced with a 15 mph quartering wind, judging the wind drift
is crucial for correct shot placement.
There are many good
ballistic programs that work out the wind for you but you still need
to know the bullets characteristics and velocity to apply the data
correctly and not least you still need to be a good shot to execute a
hit.
There are many ways to
judge wind conditions and I will run through a few and show how I use
them when out stalking or fox/vermin control to good use. There is no
easy method to learn wind corrections, you have to get out and
experience the winds characteristics out in the field. I have used
steel silhouettes of game for decades now as these give an audible
and visual indication of correct shot placement.
Wind, what is it
There are two important
elements to consider when trying to apply a wind drift calculation
when you are out shooting. Firstly the wind speed, which rarely stays
constant and secondly the direction of the wind, both will cause a
myriad of differing wind drift on your bullet in flight. The effects
of the wind are not linear as the effects of the wind are increased
as the range increases. It is therefore imperative to be able to
correctly determine the wind direction and the wind speed. The
trouble is that the wind rarely stays the same intensity or direction
along the bullets flight path and you will need to “dope” the
wind from visual signs as the bullet travels along.
This is where technology
can begin to help you. Range estimation is a crucial part of any
shooters skills but with the advent of laser rangefinders and even
laser finding scopes have meant more accurate shot placements can be
made so long as you can shoot straight in the first place!
More difficult is judging
wind direction and intensity. Intensity can be accurately measured
with the aid of a wind meter but this only gives the wind speed at
your position not down range where it is crucial.
You will learn these with
a good wind meter such as the Sky Mate I use. Choose a likely area
that you stalk regularly and take wind readings at each location
within that area , say valley bottom, hillside, beside some trees ,
prone or from a high seat. Keep a record of the wind speeds and how
the foliage is reacting where you are. This way you can build up a
mental image of how foliage reacts to wind speed and translate this
information to an unfamiliar shooting area.
Skymate wind meters from JMS Arms.
As a general rule wind
intensity can be categorised as follows:-
0-3 mph The wind is hardly
felt on a cheek but smoke or pollen drifts gently
3-6 mph Gentle breeze that
is felt on the face and leaves rustle.
6-8 mph Moderate wind that
make grass tops sway and leaves and light twigs move.
8-12mph A Fresh wind that
moves branches and bushes, heather sway.
Up to 16mph Is termed
Strong, and small trees sway
20mph Strong wind
conditions, leaves on ground blown around and larger branches move.
This is only half the
battle now, you have to determine wind direction and then compute all
these factors into determining how far off zero your bullet will be
at any given range you take the shot.
Direction Finder
A wind speed variation is
far easier to feel than a direction change of the wind yet it is the
latter that is more likely to affect your bullets path so direction
finding is very important.
Use your eyes:- foliage
down range to the deer can tell you a lot about the winds eddies and
still spots but try to view only the foliage that is at the same
level as the deer and bullet flight as this is what is going to
affect your bullet. In other words tree tops bending will not affect
the bullet when at ground level only a breeze or light wind is
blowing. Again practice, in a regular area I tie small pieces of
surveyors tape to bushes, gates, posts, trailers! Just a small
indicator of a “real time” wind movement or direction.
The less time the bullet
spends in the air or flight the less time wind has a chance to act on
it, that is why velocity and a good Ballistic Coefficient (BC) are
important factors when choosing a bullet or cartridge.
Clock it
Use the clock system to
determine the affect the wind direction will have on your bullets
impact point. If you
think of yourself at the centre of a clock face and looking down onto
yourself the wind at extreme angle (90 degrees) to your rifles barrel
i.e. 3 or 9 o’clock will have the most wind force on your bullet.
But what happens at a lesser angle at 1, 5, 7 or 11 o`clock?
Here’s a simple rule:-
Anything from 3 to 9 is full wind value (100%)
2,4,8,10 is 60%
1,5,7,11 is 30%
Died in the wool long
range shooters will tell you there are a lot more subtle values at
1.30 o`clock etc but for this simple test just use the above, its
better than not compensating at all.
To keep it simple, here`s
what differing wind speeds and directions can do to three popular
cartridges, the .223, .243 and .308.
.223 40 grain V-Max
at 3825 fps and 1300 ft/lbs BC 0.275
10mph Wind
|
Muzzle | 100yds | 200yds | 300yds |
3 or 9 o`clock Full
|
0 | 1.15 | 4.8 | 11.0 inch |
2, 4,8 or 10 o`clock 60%
|
0 | 0.7 | 1.0 | 5.8 |
1, 5, 7 or 11 o`clock 30%
|
0 | 0.35 | 1.4 | 3.3 |
.243 100 grain
Sierra Game King at 2850 fps and 1804 ft/lbs BC 0.423
10mph Wind
|
Muzzle | 100yds | 200yds | 300yds |
3 or 9 o`clock Full
|
0 | 0.8 | 3.1 | 7.0 inch |
| 2, 4,8 or 10 o`clock 60% | 0 | 0.5 | 1.9 | 4.2 |
1, 5, 7 or 11 o`clock 30%
|
0 | 0.2 | 0.9 | 2.1 |
.308 150 grain
Hornady SST at 2750 fps and 2520 ft/lbs BC 0.342
10mph Wind
|
Muzzle | 100yds | 200yds | 300yds |
3 or 9 o`clock Full
|
0 | 1.25 | 4.5 | 10.25 |
| 2, 4, 8 or 10 o`clock 60% | 0 | 0.75 | 2.7 | 6.15 |
1, 5, 7 or 11 o`clock 30%
|
0 | 0.38 | 1.4 | 3.1 |
Conclusions
Those
that shoot and only correct for bullet drop will almost always be
caught out by the wind and wonder why the bullet struck left or
right. It’s your duty to learn your wind characteristics of your
cartridge to ensure a humane shot. We all get caught out, I have but
you learn from it and now if the wind is too intense you can either
that a well judged shot or just leave it and walk away.
QuickLOAD
and QuickTARGET ballistics program from JMS Arms is a
superb program not only for reloading but also determining accurate
down range ballistics, including wind drift that can be printed off
and stuck to your rifles stock.
Contact
Tel JMS Arms 01444 400126 /
07771 962121
Quickload and QuickTARGET
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