There has been quite a debate on reading wind which will no doubt go on forever, but I am trying to work out some thing on a tangent to the debate. I am using a 308 remington Accutip 165 grain round and have found (whilst building my own Data - Flash card) that the bullet drop varies a bit from the actual book values given by Remington, which I would expect. Please don't chastise me for using these rounds 'cos they are about the best I can find around here. What I would like to know is if the actual physical wind effect on the projectile will vary from the book data as well. I had a situation recently where book data gave me around 36" for a particular wind speed and it turned out to be 50 odd inches instead. This is not too say that I misread the wind, but I could hardly feel it on my face and classed it as more of a drift than a wind which was also stable.(I said about 5mph) The altitude here is about 240 metres which is roughly 800 feet above sea level, dunno if that makes a difference as well ? So, continuing, are these ballistic tables which are supplied by the ammunition companies calculated at sea level ? Cheers, Pete.