Physical wind deflection Vs book value

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by peterb, Jun 27, 2009.

  1. peterb

    peterb Active Member

    Jul 17, 2008
    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 ?


  2. Mikecr

    Mikecr Well-Known Member

    Aug 10, 2003
    Ballistic tables in a book are no better than reloading criteria in a book..
    There are just too many local variables unaccounted for.

    Get ballistic software, and calibrate it to your conditions.
    That's my advice.

  3. davewilson

    davewilson Well-Known Member

    Feb 19, 2004
    most of the long range shooting that i've done is across valleys between 2 mountains here in Pa. i get a wind reading from my Kestrel and then 2-2.5x it to come up with a correction for the wind. reason being it's always more out in the valley than it is on the mountain side. unless i'm very exposed on a cliff type rock, this seems to work fairly well for me.