Question about wind drift?

Discussion in 'Long Range Hunting & Shooting' started by DontKickDontKill, Dec 9, 2006.

  1. DontKickDontKill

    DontKickDontKill Active Member

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    I have always been of the thinking that at longer ranges the bigger slower bullets though slower and dropping more did a better job at bucking the wind.....I just read something on another forum where a senior member said that slow heavy bullets always drift more cause they are "in the wind longer" and have more chance to drift?????

    This is opposite of how I have always thought?
     
  2. Eaglet

    Eaglet Well-Known Member

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    The less time a bullet takes to hit home the less it will be deflected by the wind. This is true. When looking for bullets that will be less affected by the wind, regardless of caliber and bullet weight, you want to look at the BC (Ballistic Coefficient) of the bullet. The higher the BC the better the bullet resists the wind, the less velocity it looses, the faster it will get to the target.

    Example: Both at sea level, and same muzzle Velocity = 2700 ft/sc, Wind= 5 mph

    30-06 Fed Pro-Hunter <font color="blue">BC=0.249 </font> Wgt=180 gr 1000 yds deflected 110.74”
    243 Rem Ext Range <font color="red">BC=0.403 </font> Wgt=105 gr 1000 yrds deflected 63.38”

    Velocity of both bullets at 1000 yds is:
    30-06= 824 ft/sec
    243= 1080 ft/sec

    The bullet with BC = 0.403 (105 gr.) whipped the other one by a large margin.

    If both bullets had had the same BC in spite of the difference in weight, the results would have been identical up to this point.

    Now, the energy for our example is identical for both bullets... 30-06=271 ft-lb. 243=272 ft-lb.

    I hope this shows how important BC is in shooting long range. When you get high BC together with high speed, now you're cooking! /ubbthreads/images/graemlins/smile.gif
     

  3. Jon A

    Jon A Well-Known Member

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    To clarify, TOF is only one factor. BC is a bigger factor. A higher BC bullet can have less drift even with a longer time of flight. The wind has less effect on the high BC bullet over the time it's flying. In sort of the same way the air has less effect on it longitudinally (it doesn't slow the bullet down as fast--the high BC bullet keeps its velocity better over the same TOF as well).

    The "senior member on another forum" is incorrect.
     
  4. Eaglet

    Eaglet Well-Known Member

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    Tha's correct!
     
  5. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    [ QUOTE ]
    The "senior member on another forum" is incorrect.

    [/ QUOTE ]

    Yes he is. I'd bet he is kinda like I was about 2-3 years ago. Those superfast light bullets would work for 1000 yd stuff in my head. Then I tried them. Boy was I wrong!!!! You think you know it all and then you listen to someone and find out otherwise!!!
     
  6. DontKickDontKill

    DontKickDontKill Active Member

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    Thanks for the reassurance.....I didn't mean to sound like a rookie, cause I am really not, but just wanted to make sure I wasn't crazy.....