# Best Spin Drift online calculator?

Discussion in 'Long Range Hunting & Shooting' started by Litehiker, Dec 4, 2019.

1. ### dfanonymousWell-Known Member

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The military does. Magnus was the one that came up with the theory for what’s know as the magnus effect when studying artillery while gyroscopic drift may sound similar but is another issue. Artillery is another story entirely, also keep in mind these are area effects weapons. As for snipers, the military got rid of spin drift for a long time then brought it back when software became standard equipment as far as its teaching. It’s not something that is of common concern in small arms due to its relatively small yield in deviation in most military operations. Most salt dog snipers don’t worry about it. You do get to learn about it when you go to follow up courses.

Artillery you have a kill area of 150 ft and cas area of 300...now I was not an arty guy but as a guy who’s called for fire I’d imagine they don’t want to let a 155 drift off 20 mils at 13 miles...

As to the equation and why it’s hard, you should read the article. I don’t speak nerd, they call people like me a knuckle dragger for a reason, and I don’t like copying and pasting other people’s work. But it has to do with the, as stated, a (quasi)linear formula working to solve a non-linear equation. The litz formula tends to work well with burger vld bullets for obvious reasons and is “close enough.”

While they can see the spin drift using equipment, to calculate it is another story. To use a standard value, would require each bullet company for each bullet to have a value for every twist and every speed (tof) for it to be as simple as that.

They have used “super computers” in the form of 6 DOF models and PRODAS. The over all conclusion is that for the most part, 2% of drop tends to be closer to the reality of the bullet impacts (in gyroscopic drift) at range then a linear formula. I suspect because there is no accurate way of calculating a scale factor for assorted bullets and thus the nerds need to rely on 6 dof models.

2. ### LitehikerWell-Known Member

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Brent,
"... because the designs are so different..."
By that I take it you mean bullet designs. Yeah, likely even "hybrid" secant/ogive designs differ between Berger and Hornady, not to mention boat tail angles, meplats, etc.
As you say"...overly complicated"

Eric B.

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3. ### BrentMWell-Known Member

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Exactly. Testing all this takes a lot of resources and time and very little payback if any. Military doesn’t use a plethora of bullets or cartridges, they have a massive budget, and outside of arty, don’t shoot elr like civi’s do.

4. ### sturnerWell-Known MemberLRH Team Member

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I have been using Applied Ballistic
But dang I want what you are using

5. ### BrentMWell-Known Member

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Applied is a little better program. It has a wind segmenting function that is fun to play with. Shooter is what I use primarily when not using my sig 2400. It uses the applied ballistic engine.

6. ### Capt RBWell-Known Member

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4dof on my phone gives everything. I shoot alot of angled shots The settingds in 4dof will be spot on if you use the phone and turn everything on compass the da can be taken from the phone's weather station corriollis powder temp stability factor can be put in etc etc. I'm within a 1/10 out to 1420 with a 6.5cm and a 7 mag the only things I've shot that far. The 270 and 243's are doped to 1270 with highly accurate predictions from -12-62 degrees in temp 600-1900ft of elevation. I'm confident I can make 1st or second round hits as far as I can get a range on a target. If I miss it's not the dope on the shot it's the dope driven that shot

7. ### Dog RocketWell-Known Member

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It is pretty amazing that you can be that consistent. Varying optical effects from day to day, or even hour to hour, can put most people off by at least a couple of MOA at those ranges.

8. ### dfanonymousWell-Known Member

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The phones weather station....it’s all you need.

9. ### Dog RocketWell-Known Member

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.

Last edited: Dec 8, 2019
10. ### BrentMWell-Known Member

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Can’t use that in my area. Weather station and shooting location could be vastly different

PLUS I rarely have cell coverage.

Last edited: Dec 8, 2019
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11. ### sturnerWell-Known MemberLRH Team Member

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I got the kestrel link also

12. ### Capt RBWell-Known Member

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I can input everything needed for the shot into 4dof then it will compensate the up for atmospheric jump for right to left or left to right wind. As far as optical changes due to sun position in the sky cloud cover etc. That is an experience thing like you said. as long as your correcting your DA as you make the shot and are conscious of the bend in light as the sun moves in the sky from morning to night your dope should be consistent. If you shoot at all different hours of the day Summer and Winter you will be able to record that and correct for it.

13. ### LitehikerWell-Known Member

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So until this year the Kestrel 5700 and earlier used Applied Ballistics (AB) programming for there engine. Then Hornady's 4 Degrees of Freedom (4 DOF).

Ad far as I know about the only difference between the two is that 4 DOF corrects for bullet attitude (angle of attack in relation to the trajectory).

Is this "IT"? Is this the main or only difference between AB and 4 DOF?

Eric B.

Last edited: Dec 8, 2019
14. ### BrentMWell-Known Member

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6 dof is really the way to go if you want to dig deeper. I did a bit of research when reading one of litz books about the different systems and forget the details as the difference was not really meaningful until shooting extreme ranges. King of the 2 Mile and beyond type stuff. Most of the engines will get an experienced shooter on target, no problem. However, shooter error to get on target for 1st round impact beyond 1k are in the high 90% range. Go to any long range comps and see the impact percentage on moa targets past 1000 and is dang low.