Re: Reading the wind for beginners
Frank has offered alot of good information. I teach my students that the only wind speed to be determined is at the shooters location(science). All things being equal, flat terrain and no trees, the wind at the target will more or less be the same. Of course it isn't, ever, but in theory the wind 1000 yards from where you are will be the same as the shooter's position on perfectly flat ground with no terrain. The shooter's job is to look at the surrounding terrain, mostly upwind, and determine how it will affect the wind's velocity at various points along the bullet's flight path. What I do is then create an "average" wind based on the wind speed I know at my location, and how I feel the upwind terrain is affecting the wind downrange. (As Frank says, art dept.) Is the average wind over the 1000 yards more or less than at my location? That is all I worry about.
In truth, wind shooting strategy is far more important. If the wind is left to right to whatever degree and I am not certain the wind will move the bullet off the right edge of the target with a left edge hold, then I will always start with an upwind left edge hold. This assumes a wind at my location that if it were constant to the target would result in a theoretical hit with a left edge hold. If I have completely blown the wind call, and I have many times, the worst case scenario is a left edge hit. Obviously this works both directions but at 1000 yards you have to allow for spin drift as a right edge hold with zero wind affect could lead to a miss with a right twist barrel.
It is not uncommon to see left to right mirage running horizontally and still need almost no left hold. Mirage in my experience can be unreliable as a wind indicator because it is difficult to tell where the mirage is in relationship to the target many times. On many ranges the berm itself creates a horizontal wind that doesn't exist even 20 feet in front of the berm. A canted tailwind will hit the berm and turn creating a mirage that is completely horizontal while the wind has almost no affect on the bullet's flight path. I have seen this on many ranges. For these reasons in winds less than 10 mph I feel that a good strategy is more more important than determining an exact average wind speed. In winds of more than 10 mph I will move upwind of the target but typically only half of what I calculate the actual correction to be. I find that almost always, the wind correction is less than I and others believe it to be.
All of this is affected by TOF as Frank mentioned. Most new shooters don't fully understand the importance of ballistic efficiency in long range shooting. Long range shooting is a game of tenths of inches and creating a caliber/load/bullet combination that removes .1 mil of wind correction at 1000 yds can increase the probability of your round hitting the target dramatically.
I don't post alot on SH because I shoot full-time and am lucky to be able to shoot long range many days a month. My advice is to spend more time on the range and less time on the computer. Keep your approach to reading the wind simple and use strategies and ballistics that give you the highest probability of hitting the target even when your estimation of the wind is incorrect. Good luck and good shooting.
Frank has offered alot of good information. I teach my students that the only wind speed to be determined is at the shooters location(science). All things being equal, flat terrain and no trees, the wind at the target will more or less be the same. Of course it isn't, ever, but in theory the wind 1000 yards from where you are will be the same as the shooter's position on perfectly flat ground with no terrain. The shooter's job is to look at the surrounding terrain, mostly upwind, and determine how it will affect the wind's velocity at various points along the bullet's flight path. What I do is then create an "average" wind based on the wind speed I know at my location, and how I feel the upwind terrain is affecting the wind downrange. (As Frank says, art dept.) Is the average wind over the 1000 yards more or less than at my location? That is all I worry about.
In truth, wind shooting strategy is far more important. If the wind is left to right to whatever degree and I am not certain the wind will move the bullet off the right edge of the target with a left edge hold, then I will always start with an upwind left edge hold. This assumes a wind at my location that if it were constant to the target would result in a theoretical hit with a left edge hold. If I have completely blown the wind call, and I have many times, the worst case scenario is a left edge hit. Obviously this works both directions but at 1000 yards you have to allow for spin drift as a right edge hold with zero wind affect could lead to a miss with a right twist barrel.
It is not uncommon to see left to right mirage running horizontally and still need almost no left hold. Mirage in my experience can be unreliable as a wind indicator because it is difficult to tell where the mirage is in relationship to the target many times. On many ranges the berm itself creates a horizontal wind that doesn't exist even 20 feet in front of the berm. A canted tailwind will hit the berm and turn creating a mirage that is completely horizontal while the wind has almost no affect on the bullet's flight path. I have seen this on many ranges. For these reasons in winds less than 10 mph I feel that a good strategy is more more important than determining an exact average wind speed. In winds of more than 10 mph I will move upwind of the target but typically only half of what I calculate the actual correction to be. I find that almost always, the wind correction is less than I and others believe it to be.
All of this is affected by TOF as Frank mentioned. Most new shooters don't fully understand the importance of ballistic efficiency in long range shooting. Long range shooting is a game of tenths of inches and creating a caliber/load/bullet combination that removes .1 mil of wind correction at 1000 yds can increase the probability of your round hitting the target dramatically.
I don't post alot on SH because I shoot full-time and am lucky to be able to shoot long range many days a month. My advice is to spend more time on the range and less time on the computer. Keep your approach to reading the wind simple and use strategies and ballistics that give you the highest probability of hitting the target even when your estimation of the wind is incorrect. Good luck and good shooting.
