The best windmeters are made by Kestrel. I started with their 3000 model and upgraded to their 4500NV.
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They don't just read the wind...they are barometers, a compass, an altimeter and a thermometer. They can assimilate this information and give combined data...readings such as density altitude are relevant for shooting...but if mountaineering things like wind chill and Pressure Trend's are useful...one for a warmth assessment and the other for determining advancing bad weather. As far as shooting goes the information you need to take and understand is basically as follows....
Windspeed and direction comparative to the intended flight of the bullet. At a right angle to the bullet path it is "full value"...or for me I prefer to think in terms of "clock face" directions..."full value" is 9 o'clock or 3 o'clock then you have 2/3rds value at 8 and 2 or 10 and 4...and 1/3 value at 11 and 5 and 1 and 7 with a head wind at 12 and a tail wind at 6. The angles of the wind have differing effects on bullet movement in flight.
Altitude combined with Barometric pressure gives information as to the density of the air you are shooting in...thinner air at altitude provides less resistance on the bullets progress...in simple terms the bullet travels faster...this impacts on the elevation adjustment needed.
Direction of shot impacts at long range because of the coriolis effect of the earth spining and how this effects gravitational pull...coriolis is basically understood by which way water runs down a plug hole...this differs between the Northern and Southern hemispheres...combine this with the axis of the earth and you have the equivalent of g force or pull on the bullet when travelling through the air...this varies according to the direction you shoot in and according to a Northern or Southern hemisphere location. A complicated issue but made easier by modern ballistic programmes which if loaded on a multi function mobile phone or on a pocket note book enable you to work these out by simply adding the relevant data and it doing it for you.
Another issue which these programmes address is "spin drift" of the bullet. This is caused by the direction of the rifling in the barrel. Most rifling is a right hand twist meaning the twist of the rifle goes from right to left...rarely you could have a custom barrel done with left hand twist...I have never encountered this. In essence the bullet spining "clockwise" causes it to drift in direction to the "right" over distance. It is to do with air density and cutting a swathe through it by spinning in one direction. On average a right twist barrel causes bullet drift of 1 MOA or 10 inches right at 1000 yards...but again this varies on air density.
Then after this is "velocity" of the bullet...whilst the bullet is supersonic it progresses in a relatively uniform direction...when it enters a "transonic" velocity as it progresses towards subsonic velocity it starts to wobble and can destabilise...with a .308 at 1000 yards it is not uncommon to see bullets of certain design enter targets side ways...the bullet at that distance has tumbled due to velocity decreasing below the supersonic threshold of 1000 fps but there is good evidence that there are problems created in the band of 1100 fps to 1000 fps or the "transonic period".
Finally there is the design of the bullet itself...this is referred to as the BC or ballistic co-efficient of the bullet. Like the hull of a racing yacht some bullets have less drag going through the air as do hulls going through the sea. They also resist sideways drift from the wind better than other designs because they offer a more sleaker shape. Shooting a .308 you need to pay very careful attention to bullet choice at distance...a 155g HPBT/VLD bullet seems to be the best choice for 1000 yards but heavier bullets do retain momentum better and some have tried 175g HPBT/VLD designs...it can also be a "barrel" specific thing as to which shoots best as well...but all told...a .308 is right on the cusp of failing at 1000 yards and is a challenge to shoot it at that distance...because the lower the velocity at this distance the greater the wind movement of the bullet. To shoot this calibre well at distances like this you definately need a 30 inch barrel to maximise the velocity gained from the powder charge in the case. A stalking length barrel will struggle and really for sniping rifles at 24 or 26 inch barrels the maximum effective range is for most locations at Sea Level about 800 yards. You can do further in higher altitude/thinner air locations.
So aside from a wind meter you should consider a range finder as well. The bino's in the above photo are Lieca Geovids with a built in laser range finder good for 1200 yards...unknown distance shooting is made a lot easier with this method of "knowing" the distance.
To maximise your scope elevation movement you would need an incline rail for the action...the one pictured is inclined at 20 MOA downwards to give a 100 yard zero at the beginning of the scopes vertical travel of there abouts. It makes up for the alteration needed because of the height of the scope above the bore of the rifle.
Having covered scopes and rifle calibre choice once you have an inclined rail and good mounts and a wind meter and a range finder...the last thing you need is a ballistic programme. There are many out there...the ones I like are two matching products....one software programme works on your laptop and is called Precision Shooter's Workbench and the other works on a phone/note book and is called Feild Firing Solutions...both are made by Lex Talus and can be found by going to
www.lextalus.com and ordered and downloaded on line. The benefit of these is in a nutshell...they allow for 3 different wind conditions prevelant on the bullet flight path...which at long range is often the case because of topography such as hills...valleys...etc...which the wind will deflect off or be sheltered from...and these programmes enable a true click value for your scope to be entered...the best you can do on a scope is have "consistancy" usually...and the true click value is often not exactly 1/4 MOA or whatever the click value...this induces error when clicking for a distance shot...so once you have calibrated your scope properly...ideally in a tunnel range...you can work out the true click value and add this into the programme.
So really there is quite a lot needed on top of your rifle and scope and bullets...but it is a challenging hobby to get to grips with...when you do and you get this base knowledge...then the learning curve starts on assessing the land features you are shooting over and how these will effect your shot as well as the wind. This is why a long range shot is "composed"....but there is tremendous satisfaction in hitting something in a different Zip Code to where you take the shot from...plus with bullet flight time you can take the shot...recover ... and then watch to see if it hits...but you need a highpowered Scope for this and in truth it is often a quick second shot taken aiming off from the first impact which gives you your "hit"...especially at over a mile. Let me know though how you get on....like you said earlier...building skills at 300 yards works for 1000 yard shooting.
Here is a good link to learn the basic effects of spin drift ( gyroscopic drift ) and coriolis effect for shooting in the USA...
http://bryanlitz.bravehost.com/GyroCor.htmlBryan is a good long distance shooter and designs aerodynamic aspects on missiles...so he has a brain much better than mine for getting this stuff "explained" easily. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />
