Wind drift?

Discussion in 'Long Range Hunting & Shooting' started by mnhunter2, Oct 19, 2008.

  1. mnhunter2

    mnhunter2 Well-Known Member

    Messages:
    46
    Joined:
    Jul 9, 2008
    I am new at working on my long range shooting and have been shooting a 150 gr bullet out of a 300wtby with 77.5 gr of IMR 4831, I cant measure muzzle velocity but I am guessing 3150-3200 and I was wondering how much a 10 mph cross wind would move this bullet at 400 yds? How much will a 20 mph wind effect it?
     
  2. Ridgerunner665

    Ridgerunner665 Well-Known Member

    Messages:
    553
    Joined:
    Sep 15, 2008
    This gets complicated (not really...but sorta)

    To answer that question accurately I'd need to know the ballistic coefficient of the bullet and its muzzle velocity.

    I could probably get close by quesstimating the muzzle velocity...but the ballistic coefficient has to be correct to even get in the ball park.

    Edited to add: If I were shooting a 300 magnum (of any flavor)...I'd be shooting much heavier bullets than 150 grains. The 190 to 240 grain bullets will fly WAAAAY better in the wind than any 150 ever made...the heavy (longer) bullets have a higher ballistic coefficient.
     
    Last edited: Oct 19, 2008

  3. mnhunter2

    mnhunter2 Well-Known Member

    Messages:
    46
    Joined:
    Jul 9, 2008
    The ballistic coefficient is .435.
     
  4. KRP

    KRP Well-Known Member

    Messages:
    591
    Joined:
    Dec 25, 2007
  5. Ridgerunner665

    Ridgerunner665 Well-Known Member

    Messages:
    553
    Joined:
    Sep 15, 2008
    Figured at 3,200 fps...
    2.4 MOA (5.5 inches) at 400 yards in a 10 mph crosswind.

    4.8 MOA (20.2 inches) at 400 yards in a 20 mph crosswind.


    2500' elevation, 60% humidity, 59 degrees, barometric pressure 29.92
     
  6. JLR

    JLR Well-Known Member

    Messages:
    155
    Joined:
    Mar 6, 2007

    Might want to check math for the 10mph wind....me thinks 2.4MOA is around 9.6" at 400yds??:confused:
     
  7. yobuck

    yobuck Well-Known Member

    Messages:
    853
    Joined:
    Aug 23, 2008
    il'l start the argument.

    first off, you have a fine cartridge. you may be aware that the world record for 10 shots at 1000 yds. has been held by that cartridge for about 14 years now.

    400 yds.is a cakewalk for that cartridge. wind affect would be minimal unless the trees are bending. the bullet is there, like right now. i would hold over just a little.

    that said, your using the wrong bullet for long range in that gun. you will get better results with heaver bullets. certainly initial velocity will be lower, but at longer ranges that will reverse itself. wind affect will be less also. id be using something in the 168 to 190 range. sierra machkings would work fine, and yes they will perform well on game
     
  8. Ridgerunner665

    Ridgerunner665 Well-Known Member

    Messages:
    553
    Joined:
    Sep 15, 2008
    We're both wrong...those #'s are the ones JBM spit out.

    Using my math and a calculator...I came up with 10.05 inches.

    1.047 x 2.4 x 4 = 10.05"

    I apologize for not checking the JBM math...I thought it was better than that.
     
  9. JLR

    JLR Well-Known Member

    Messages:
    155
    Joined:
    Mar 6, 2007
    Crap, you're right. I left out the .047 part, LOL.
     
  10. mnhunter2

    mnhunter2 Well-Known Member

    Messages:
    46
    Joined:
    Jul 9, 2008
    I agree I am not using the right bullet for the best long range hunting but I have these bullets on hand and I will be leaving in a couple of weeks and don't want to start to build a new load at this date. I changed the bullet seating depth so it just fits in the magizine and the accuarcy improved. I will be looking for advice on a bullet to use on light skinned game and that will expand well.