How critical is scope level?

Discussion in 'Long Range Hunting & Shooting' started by CM-RHG, Jan 10, 2019.

  1. CM-RHG

    CM-RHG Previously Chuck Moles

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    Most everyone understands that the crosshairs on a scope and barrel center vertical alignment are ultra critical for shooting longe range. My question is this. If you have a scope height of 1.75" above barrel center, in a perfect world, how much would 1 degree of left or right cant while shooting effect point of impact at 1000yds? 1 degree in 1.75" is .031". Perfect world, no elements

    Thanks
     
  2. Rifleman97

    Rifleman97 Well-Known Member

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    Well that would depend on the ballistics, I’d you have a flatter shooting cartridge, it would fall less and therefor be closer to the crosshair than one of a slower bullet.
    For example (making up numbers here for simplicity’s sake)
    If you have one bullet moving at a speed that it drops 200 inches in 1000 yards, and another that drops 400 inches, because of the linearity of the slope relative to the crosshair, it would be twice as drastic of a change at that range.
    So for inches I thew in some made up numbers into a ballistics calculator for some perspective. I just said a 200 grain bullet with a velocity of 3000 FPS with a BC of .7 at 29.6 relative Hg/in 2500 feet at 20° With 50% humidity. (All just semi realistic numbers I just made up for sake of calculation)
    At 1000 yards the calculator said it would drop 236.5 inches. At .0175 inches off of parallel per inch, times 236.5 that would equate to roughly 4 inches off target.
    I could be using the wrong math here though because even though one degree isn’t much, I feel like it should be a bigger number than that.

    I’m going to do some research and get back to this thread if I find a mistake in my math.
     
  3. Rifleman97

    Rifleman97 Well-Known Member

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    Okay so I did a little research and I found my numbers to be correct, however with a less magnum round than my hypothesised one and the impact would be more in the range of 8 inches.
     
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  4. CM-RHG

    CM-RHG Previously Chuck Moles

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    My 2 most common builds are 7RM and 28 Nosler. 7RM shoots the Berger 195 at 2950, 28 shoots it at 3100. That bullet BC is .754 7RM path drops 232" and the 28 Nosler drops 205".
     
  5. Rifleman97

    Rifleman97 Well-Known Member

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    Here’s the formula
    A(.0175)(x°)
    Where A is the amount of drop at the range you’re shooting at and X is the angle in degrees your scope is tilted.
    So it would be
    232(.0175)(1)
    4.06”

    205(.0175) (1)
    3.58”
     
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  6. Rifleman97

    Rifleman97 Well-Known Member

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    Its not exact but it’s very simple and gets you within an inch of where the full series of equations I did will get you.
     
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  7. CM-RHG

    CM-RHG Previously Chuck Moles

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    Thank you very much....
     
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  8. BoomFlop

    BoomFlop Well-Known Member

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    Although those numbers don’t seem like much at 1000 yards, I would be willing to bet that holding sighing 1 degree (even with a level) to be pretty difficult (even more so in a hunting situation).

    I could be wrong, but 1 degree isn’t very much at all.
     
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  9. bgbuck153

    bgbuck153 Well-Known Member

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    I’ll jump in... bullet coriolis! If you have a RIGHT twist barrel which way would you twist the scope to account for the coriolis of the bullet ; clockwise or counter clockwise ?
     
  10. joseph singleton

    joseph singleton Well-Known Member LRH Team Member

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    WHAT ?????
     
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  11. Capt RB

    Capt RB Well-Known Member

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    Check out the dtr reticle
     
  12. BoomFlop

    BoomFlop Well-Known Member

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    bgbuck153

    Are you basically asking which way you would cant the scope if you were trying to correct for spin drift? It would be clock wise, so that the cant (bottom of reticle) is left of center...with spin drift it would put it back on. That is assuming that the amount of spin drift and scope cant could possibly even be remotely matched up.

    Steve
     
  13. bgbuck153

    bgbuck153 Well-Known Member

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    Yes I was thinking spin drift and typed coriolis. Lol. Brain fart
     
  14. rfurman24

    rfurman24 Well-Known Member

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    First off you most likely could not detect 1 degree even if your scope was mounted perfectly and you were using a scope mounted level. The piece I have seen no one mention is if the scope is not level your elevation will not be true because as you click up you are actually clicking up and to the right or left. The amount you will be short will be dependent upon how many degrees the scope is canted. The total amount of error would be measured in MOA or MILS and zero correlation to cartridge being shot.
     
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