Coriolis effect?

Discussion in 'Long Range Hunting & Shooting' started by RangerBrad, Dec 21, 2013.

  1. RangerBrad

    RangerBrad Well-Known Member

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    I was watching a show I can't rember if it was on youtube or tv, however a man was showing the effects of corolis on poi. He shot 5 shots at 1000yds directly west that grouped 8" low and 5 shots at 1000yds directly east that gropped 3" high. I have never figured in corolis as I shoot 500-700yds and felt at that distance it didn't make much diffrence however, I have found that at one place I shoot(where I sighted in my rifle that i'm nailing it at 500yds and another place my shots are low at same range. This gentelman also stated that rifles should be centered either north or south but to my mind if you do that arent you just trading elevation for windage. What are yals thoughts on coriolis and at what distance do you consider it? Brad
     
  2. Broz

    Broz Well-Known Member

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    Know your latitude, and use a program that will include coriolis in the shooting solution. Then play with it to decide at what range and what direction you choose to include it. No the ballistic Rf's do not account for this. Oh and don't believe everything you see on TV.:)

    Jeff

    Edit PS: For my most proven long range rifle there is exactly 1/2 moa at 1000 yards between a 90 degree and a 270 degree shot. So 5.23" difference at this location. Definitely worth considering in some instances.
     
  3. Shane1

    Shane1 Well-Known Member

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    I figure if the shot is long enough to need correction of any sort and your using a ballistic program anyway why not factor everything possible in. Does it make enough difference at 500 to matter? Maybe, say if your shooting at a 1/2 moa target but what it does for me factoring everything I can into every shot builds good habits so when the shot comes that really matters I don't find myself trying to factor in something I'm not familiar with. It's easy to punch in a couple extra variables into a ballistic solution. Adds to consistency, which is really what were all after in long range shooting. To accurately hit the target every time.
     
  4. Kennibear

    Kennibear Well-Known Member

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    Good luck finding a LR shooting spot that points due Geographic North (not magnetic). Have a good surveyor for a friend?

    As good as it sounds it is not practical. Find a range and factor the latitude and magnetic into the program. About as good as can be done.

    KB
     
  5. MontanaRifleman

    MontanaRifleman Well-Known Member

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    It's not hard to figure magnetic declination if you know it and it's not hard to find out what it is in a particular area. Generally, East of the Missisppi you add to the magmetic heading to get true and West you subtract. Here in Montana it is bout 15* give or take.

    A little googling will get you real close.

    https://www.google.com/search?q=mag...www.thecompassstore.com%2Fdecvar.html;677;578
     
  6. Kennibear

    Kennibear Well-Known Member

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    MontanaRifleman

    Copy your statement.

    What I really meant was for most people like me the longer ranges we use to sight in are driven by terrain, that is we shoot down a valley or some such thing. A target set up geographic due north probably isn't in the cards (or the terrain). So in the end we are going to factor the offsets, compass, latitude, magnetic correction etc.

    Other than the wide open desert true north isn't happening. So we do the math anyway. At 1000 yards we should be doing the math.

    KB

    P.S. Big like on your insight! Thanks!
     
  7. Greyfox

    Greyfox Well-Known Member

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    I don't take CE into consideration for my hunting at 1000 yards or less. At greater than 1000 yard shooting, I do. At the longer ranges on windless days I have seen the ability to place shots more accurately by programming azimuth and latitude into my calculator, especially if I'm shooting east or west. It's not much of a big deal. For a given area, latitude isn't going to change much if any, and azimuth is just taking your compass reading and loading it in. Takes about 10 seconds more time.
     
  8. Scrubbit

    Scrubbit Well-Known Member

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    I use CE (horizontal component) on all long range shots as I'm at 62 28N. Only use aximuth (vert component) at around 800m+.