Long Range Zero?

Graham

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Long Range Zero?

Effective practical precision riflery is about knowing what matters to the shot and when that factor matters to getting the hit. The greater the distance of the shot, the more that the lesser things like spin drift begin to matter. At ELR distances, with very long TTT, Coriolis is one factor. Its' importance is debatable. But even then, to compensate for it, one must know how to do that correctly and be able to do it properly. The fact that an i-phone ballistics program may have a related feature does not mean that the feature is not a tourist trap.
 
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TimK

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The problem (I think) is one of relative motion. Consider a shot at a bearing of 0° taken at the equator. Coriolis theory would say that the earth would move under the bullet while it's in flight. The problem is that the shooter and the bullet in the chamber are moving at the same speed as the earth before the shot is fired. Sure the earth is moving 1,000mph from west to east, but so is the bullet in the chamber. It continues to move at that velocity from west to east after it is fired, you just don't notice it because relative to the earth's surface, it's velocity is zero.
 

lowlight

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    That is correct, part of what i said about people using the exact speed of the earth's movement and not adjusting that speed for factors like, it was once attached, the air is moving too, etc. The exact speed of the spinning earth is not a valid number, unless you are watching from the international space station.

    Dropping a bomb from a plane isn't about Coriolis as much as it is like throwing a ball from a moving car... it appears to curve too. Same with the example of the sailing ship firing a cannon, they were moving.

    Sending artillery 8, 10, 26 miles is not the same as shooting a bullet with a 1 second time of field and Max Ord of 10ft...

    Consider the guys who float in the air in a lounge chair tied to balloons. They would make history by reaching the pacific ocean in minutes, and not end up East hours later because the wind blew them that way. Reason, they never leave the boundary layer. Like [FONT=Georgia, Times New Roman, serif]Baumgartner, how did he take off from New Mexico and not Land in China ? He landed in the same state. It was just a balloon that lifted him and was not powered, it took him 3 hours to lift, I never saw him steering it. You have kids launching toys on weather balloons with cameras onboard able to retrieve them in the same state. These little kids can over come the spin, they must be junior geniuses. [/FONT]
     

    Killswitch Engage

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    it would be far more beneficial if the gunwerks clowns were informing their clients about the effects of DA on their dope. especially since they seem to think the bdc turret is the answer and users are struggling with dope changes from day to day. the effect there is plenty if the temp swing is big and the distance is 1k and beyond.
     

    RHunter

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    .08 mils is 1/4 moa at 1000 yards. I have no problem adjusting for that.

    You're so ignorant you don't even know what you are looking at. This why people say the internet is dangerous. Just enough information to be completely wrong.

    Frank, I am perfectly capable of doing the math. I am asking you the question so you explain your belief and understanding better and educate me considering you feel I am the one who has the problem. I don't have a problem with you correcting something that I believe is true, that is the point of the forum correct? as Graham says, to discover the truth?

    If it is not too much to ask, how about backing off just a little from calling me ignorant, if I was ignorant I would not be asking you to clarify or correct things you have said or things I have said so I can gain a better understanding of them. You are the one that knows the information, I do hope you are willing to share it. Rather than turn it into a session of name calling, is it too much to ask for you to explain to us/me why all these people that believe in CE are wrong or at least why it should not be considered. That way we OR I don't continue to spread misinformation and perpetuate the "myth" further.

    I am interested in hearing what you have to say on the matter from your experience standpoint, I find it to me one of the most credible in the forum. I am more apt to believe it and take it to heart when I am not being called ignorant in the discussion.

    In the terms of absolute, I consider 1/4 of an MOA to be significant at 1000 yards because 1/4 moa from CE plus 1/4 MOA from a bad wind calc, and 1/4 MOA from a bad BP reading added to another 1/4 MOA caused by a bad humidity reading added to 1/4 MOA for a bad altitude reading... the sum of all the errors equals a miss. If I can correct even one of those factors, that could be the difference of hitting the target and not hitting the target if I get everything else wrong.

    You consider 2.68 +- inches to be insignificant at 1000 yards, in the terms of everything else being correct, it most likely is, but as a LR or ELR shooter, don't we have to consider all the variables in our calculations so we can minimize the effect of as many errors as possible?

    When I originally said that you never can have a true zero at 1000 yards because of CE and the effect CE has in different directions, what I implied was the CE variations experienced from an absolute zero shooting in one direction. If there are no variations from zero at 1000 yards caused by CE when you shoot at a different azimuth than I am willing to accept that. My argument here is there is, based on what I have previously learned, regardless of how significant or insignificant they may be.

    This is what I originally said:

    Coriolis effect starts to screw with you at long range so you will never have a consistent zero at long yardages.

    Then I said this:

    Do a bit of research and you will find it is very real. Your better ballistic calculators calculate for this. Shooter for the iphone is one that considers this in its calculations.

    I never said a single word about any distance. Then I referenced the video.

    Then I said this:

    6 inch difference east to west at 1000 yards is pretty substantial in my opinion. If your vertical dope is calculated shooting east and you use that same dope to shoot west, it is the difference between a hit and a miss on a 10" target. Same shooting north to south only the effects are horizontal. 1000 yard zero shooting north will be 6 inches off shooting (1000 yards) south.

    And that is when I stepped in the shit because I made a statement that in effect said if you shoot 1000 yards in one direction, then 1000 yards in the other, the CE effect would be the same as shooting 2000 yards. A 6 inch difference. If you correct your dope for that 2.68 inches of rise or drop, turn around and shoot the other way, you will have twice that amount of difference because you calculated it at the mid point. If you left your zero at zero, you would have 2.68 inches low on one target and 2.68 inches hi on the other. The diference in the spread would be more than 5 inches. I rounded it to 6 because the belief, depending on your location in most places in the US, is 2.5 to 3 inches in 1000 yards.

    the myth is you can or have too adjust for CE inside 1000m, I never bother with it, but you can after 1500m if you feel the need.

    So am I wrong in assuming you are saying there is a difference past 1500 M that may be worth calculating for? Can you tell me what you believe the correct CE adjustment for 2000 yards would be if I was shooting east?
     

    knockemdown

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    I've been following along & I get it?

    Simply stated, any significance that the Coriolis Effect has on bullet flight at distance is lost in the error of:
    Load velocity extreme spread
    Inherent accuracy of the platform
    The ability of the shooter to consistently hold a sub 1/4MOA group
    and...
    THE WIND

    Basically, your argument is akin to pondering over how a fart will affect the acoustics of the band at a rock concert.

    For all practical shooting purposes inside of ELR range, it don't farkin' matter...
     

    RHunter

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    Simply stated, any significance that the Coriolis Effect has on bullet flight at distance is lost in the error of:
    Load velocity extreme spread
    Inherent accuracy of the platform
    The ability of the shooter to consistently hold a sub 1/4MOA group
    and...
    THE WIND

    If those are the things you can not control, then why wouldn't you attempt to correct the things you can in order to help negate some of those inconsistent variables? Even if it only made a difference in one out of 5 shots, a hit is a hit and a miss is a miss.

    Pulling my group of "mistakes" over 3" or up/down 3" may make the difference of more of those "mistakes" hitting the target.

    Like you said, it may not matter and I guess that is the sum of the debate.
     
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    knockemdown

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    Just saying it might behoove one to favor the empirical evidence over the theoretical. Several knowledgeable shooters have shared their empirical evidence and practical results, so I see no grounds or reason to argue them...
     

    RHunter

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    Just saying it might behoove one to favor the empirical evidence over the theoretical. Several knowledgeable shooters have shared their empirical evidence and practical results, so I see no grounds or reason to argue them...

    I too made my comments based on my empirical evidence and what are part of my best practices shooting at long ranges. I don't know who is capable of shooting what reading posts in a thread so it makes it a little difficult to weigh my experience against theirs.
     

    lowlight

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    I have already typed much too much here...

    I have heard the, Well if you can control it why would you not use it.

    Because it does not all go in the same direction... and it's not what you think it is. You're trigger squeeze can double SD or remove SD, so putting it on will add that error back. You cannot control your MV as you have no idea until after the shot it fired. What happens when the wind goes left, vs right, and you're now adding something because you assume it's there, and that you didn't take a lot of it out of the equation with your fundamentals or you zero.

    Take your software, tell it you have a 100 yard zero and read what the answer for your 1000 yard spin drift is. Now tell the software you have a 600 yard zero and look at the spindrift I guarantee it is the same number as your 100 yard zero. Which if you zeroed it out, how come you still need a minute.

    What happens to a bullet fired from a fixture is not the same as what happens to a bullet fired by a human. The human factor changes the game, otherwise every single person who didn't use this stuff would miss the plate, period, no debate. But that is not how it happens in real life. Guys constantly ignore it and do fantastic without it. That is what Larry Vickers calls a Clue.

    This stuff exists, but to such a small degree and like Graham said, the better shooter knows what is necessary to make the shot and what is a tourist trap to make you think it will get you on target more often. I routinely ignore it, at ELR distances I use 1/2 what a computer tells me, but only if I see the wind is below 5 MPH and in every case I worry about the wind.

    The idea you can control this stuff by adding a minute, or a minute there is lie, a completely false argument.

    We did a test with 11 shooters on a rifle at 100 yards, the rifle was zeroed in a lead sled with minimum human input to start. The spread from left to right was 2 inches among just 11 people. Another clue.
     

    RHunter

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    Well I guess another way of looking at it is this, my calculations are most likely compensating for my bad habits, both of which were developed concurrently.

    Thanks for your input into the discussion.
     

    rem `06

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    very good discussion gents! thank you

    i learned alot as well as many, i am sure.

    It once again prooves that it is all designed to sell shit! to the unknowing.

    buyer beware,right? thats WRONG!
     
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    cncwhiz

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    I asked a simple question and got a physics lesson :)

    Thanks for the great info guys. All of it was likely stuff I would have asked about sooner or later.
     

    Phil1

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    RHunter,



    As to making sport of you, sport involves a challenge and requires technique. In your case I'm not sure we're at that level.

    Ah shit now I have to clean all the coffee off my keyboard from when laughter interrupted drinking.
     

    Helopitts

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    Here is a simple way to think about it is. If you are in an airliner and you stand in the aisle and jump up you don't fly to the back of the plane.