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provide them with the opportunity to increase
accuracy in shot placement.
This is why we need wind flags – to
attempt to indicate the amount of deflection
that the wind will subject the bullet to, which
will of course, depend on the wind’s speed
and direction. Anything out there, between
you and the target, that will indicate the speed
and direction of the wind will clearly give you
a better opportunity of hitting your aim-point
– providing you can interpret the ‘condition’.
If we adopt the Swiss mathematician
Daniel Bernoulli’s theories for shooting, we
begin to see what effect the wind has on a .22
calibre rimfire bullet, over specific distances.
The diagram to the left is a metric adaption of
one produced by Joe Haller.
benchrest and even F-classers shooting at greater
distances. The wind flag is capable of imparting a
lot of information to the shooter which can and will
A wind blowing from 3 o’clock with a
velocity of around 9-10 mph, will cause
the bullet to impact approximately 25 to
26mm to the left and about 6mm high.
From the 9 o’clock direction it would impact
approximately 25 to 26mm right and 6mm
low. This change in elevation is down to the
‘Bernoulli Effect’ and the fact that most
modern target rifles have a barrel with a
right-hand twist.
Obviously, a 1 mph wind from the right will move
the bullet a tenth as far. A similar
strength wind from the 4 or 5 o’clock
direction will drive the bullet less to the
left but still slightly high. A wind from
the 6 o’clock direction will raise the
bullet impact slightly and a 12 o’clock
‘headwind’ will drive the bullet
slightly low.
The table below lists the constraints
for 9-10 mph winds and could
theoretically be used. Just remember
the wind always does what you
expect it to - until it doesn’t! Sorry but
there it is! Wind deflection is all about
reading the flags and the information
listed below are at best quite good
‘estimates’.
When actually shooting however,
you will need to consider other
issues like barometric pressure and
temperature.
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