Spin drift and Coriolis at 1000+

[Broz]

So, at 800-1000 yards, you would not worry about SD and coriolis?

So, at 800-1000 yards, you would not worry about SD and coriolis?

I ask because I just set up a range for 1100 yards and it is 208 degrees SW. I've only shot at 606 yards and I want to do all the work possible before I jump to 800 (then 1000 yards). I'm not finding a lot of material on the subject and this video has me concerned for 1,000 yards and hard to detect when we consider the 1/2 moa accuracy of a good rifle at this distance.

No, I stated earlier that I leave SD checked on as part of my shooting solution all the time. I only employ CD when going past 1200~1400 yards.

I choose to ignore that video as the data is indifferent to mine. My notes show the drifts, lifts and drops to be less at 1000 yards than shown in the video.

Jeff

 

[Archery1973]

No, I stated earlier that I leave SD checked on as part of my shooting solution all the time. I only employ CD when going past 1200~1400 yards.

I choose to ignore that video as the data is indifferent to mine. My notes show the drifts, lifts and drops to be less at 1000 yards than shown in the video.

Jeff

Thanks. That makes sense.

 

[Broz]

So this thing is telling me that in an east west situation I don't have any hoazontal (windage) coriolis?? Zero effect no matter which direction i shoot!!!!

That can't be right.

What gives???

You have something wrong in your settings I would guess.


Here are the number I ran for my 300 win. and support as to why I do what I do in reguards to using Coriolis at 1000.

Looking at elevation only here at 46* latitude where I live and hunt. A shot with a perfect West 270* azmuth for my 300 win at 1000 yards requires a dial up of 21.4 moa when corolis effect is included. The shot perfectly East 90* azmuth needs 20.9 when coriolis is included. So .5 moa difference. This is a worst case scenario shooting dead East or West. So in a worst case scenario I would shoot 2 1/2" high to 2 1/2" low and I am not sure I could detect why since my rifle shoots 1/2 moa at 1000. If I turn off the coriolis option to the solution the program says 21.2 at 1000. So it would be in error of .2 or .3 of a moa for the two shots.

1 click at 1000, I only wish I could shoot that consistant.

Jeff

 

[Michael Eichele]

, shooting north or south the earth will have rotated westward, hence the bullet will be to the right of target shooting north but left if shooting south.

FYI, bullet impact in the northern hemisphere is always to the right. Direction of fire does not matter. East and west do add a vertical component but there will always be a right hand impact.

To illustrate why it will have a right hand impact shooting north or south, see below.

Imagine shooting at a vehicle moving from right to left. If you fired while your crosshairs were right on target, your bullet would impact behind it or to the right.

You being the stationary component represent a shooter sitting on the North Pole shooting at a target on the equator. The target is moving therefore you miss.

Now envision that you're in the vehicle shooting at a target where you had been sitting. The vehicle is moving in the same direction as when you fired at it. You take aim and when your crosshairs line up with the target, you fire. Did you hit it? No. Why? Because your bullet is moving horizontally in relation to the target at the speed of the vehicle. When you fired, your bullet will impact to the right because the bullet was moving to the right when it was fired.

This represents you being on the equator shooting at a target on the North Pole.

M

 

[Joe King]

FYI, bullet impact in the northern hemisphere is always to the right. Direction of fire does not matter. East and west do add a vertical component but there will always be a right hand impact.



M

The trick is to not over think it. Take this ^ explanation and go with it. Otherwise you run the risk of your head exploding lolgun)

 

[4xforfun]

Seems like we know that there is a vertical component of coriolis when shooting E - W and W - E, but there is no horazontal (windage) element...when shooting in any direction???

REALLY????

Question....on the shooter program, is there a "seperation " between spin drift and coriolis? If I turn the coriolis off, I get zero windage at 1500 yards. I show no correction for spin drift. if I enable the coriolis, I get .4 MOA Left, no matter which direction I am shooting. Is that spin drift, coriolis, or both?? I get elevation changes ( with coriolis enabled)depending on direction I am shooting.....that is an effect of coriolis....but no affect on windage???

 

[Michael Eichele]

Horizontal in every direction

 

[Broz]

Seems like we know that there is a vertical component of coriolis when shooting E - W and W - E, but there is no horazontal (windage) element...when shooting in any direction???

REALLY????

Question....on the shooter program, is there a "seperation " between spin drift and coriolis? If I turn the coriolis off, I get zero windage at 1500 yards. I show no correction for spin drift. if I enable the coriolis, I get .4 MOA Left, no matter which direction I am shooting. Is that spin drift, coriolis, or both?? I get elevation changes ( with coriolis enabled)depending on direction I am shooting.....that is an effect of coriolis....but no affect on windage???

Yes, there is a windage correction for CD too. It is dependent on Latitude and azmuth. I think your SD is not working due to lack of entered info in your bullet data.

You can choose one or the other, none or both. SD alone should be .5 to .75 moa at 1000. My 300 win with a 210 shows 1.0 moa at 1500 for SD alone. Coriolis will either add or subtract horizontal drift to SD when both are on. For example at 1500 with coriolis on and shooting 280* azmuth I get 1.4 moa and 1 moa of it is SD.

To get your spin drift to work, and I will assume CD as well, you will need to have all and proper bullet data entered. That means bullet Dia.,weight, and Length too.

If you do not have bullet length entered that could be your problem. Hold on the bullet file, select edit and fill in the blanks then save.

Jeff

 

[4xforfun]

Yes, there is a windage correction for CD too. It is dependent on Latitude and azmuth. I think your SD is not working due to lack of entered info in your bullet data.

You can choose one or the other, none or both. SD alone should be .5 to .75 moa at 1000. My 300 win with a 210 shows 1.0 moa at 1500 for SD alone. Coriolis will either add or subtract horizontal drift to SD when both are on. For example at 1500 with coriolis on and shooting 280* azmuth I get 1.4 moa and 1 moa of it is SD.

To get your spin drift to work, and I will assume CD as well, you will need to have all and proper bullet data entered. That means bullet Dia.,weight, and Length too.

If you do not have bullet length entered that could be your problem. Hold on the bullet file, select edit and fill in the blanks then save.

Jeff

Like the song says.....WHOOP THERE IT IS WHOOP THERE IT IS..... I didn't have a value for bullet length!!! Since this was Brians' baby, I assumed that he would have the bullet lenghts automaticly listed for berger bullets!!!

I know...I know.....You know what they say about " assuming".

Gabage in, garbage out!!!!

Big thanks, things are making WAY more sence now!!!!

Tod

 

[Broz]

Big thanks, things are making WAY more sence now!!!!

Tod

Good deal!!! Glad to help. Hey, how do you think I knew what was wrong..

Jeff

 

[Michael Eichele]

Don't forget to include your rate of twist. You will need this for an accurate SD equation.

 

[Archery1973]

Lots of good info here. And from what I saw at my first shooting at 800 yards......these guys were on the money.