Extreme long range shooting

[henry d]

I was reading a book and it mentioned the "Coriolis effect" this is where the earth is turning under us and anything moving through the atmosphere would,given enough distance move to the right(northern hemis).

It used Naval gunfire as an example - as a shell fired 15 miles would fall 100yds to the right unless adjusted for.

 

My question is..........would the people shooting at bisleys longest ranges need to adjust for this

[webber]

H

 

A quick calculation in my head, indicates that as a percentage the amount is minute. Therfore in practical terms the effect acts upon all shots, but is effectivley corrected by zeroing. The effect being unconciously adjusted for as the allwance over the distance is quite small. The effect obviously becoming more pronounced as distance in miles increases.

 

webber

[henry d]

For general shooters yes but these guys shoot 1000yds+

and my amateur maths say its 3 yds,if its linear but if not it would be considerably less

[apbuild]

Henry,

 

I know that the long range target shooters have to adjust for Wind and bullet drop but as for the rotation of the earth, I can't think that they will have to allow for this.

 

 

Rob.

[Graham M]

The shot at 1000yds take @ 2 seconds to get there, so it would be a simple case of re-zeroing the sight to suit. Anyway the wind would probably blow the bullet off to the right/left more than the rotation of the earth would effect it.

G.M.

[plexer]

Well the US are trying to acheive greater accurate shots using smart shells such as the gps guided excaliber.

 

Ben

[ed.jbrown]

my dad was gunnery officer of hms antrim during the falklands and understands all this stuff.

he mentoned something like this!

 

pointless reply but there you go!

 

ed

[pin]

Henry,

 

I know that the long range target shooters have to adjust for Wind and bullet drop but as for the rotation of the earth, I can't think that they will have to allow for this.

 

 

Rob.

 

Webber said it first, but they are allowing for this, but might not be aware that they are. In the act of zeroing they will have compensated for it (however insignificant) but might not realise.

[henry d]

I see what you`re getting at but remember that most people are shooting at a distance they are comfortable with,say 300m and for longer shots,say 600m,they may be able to dial in the bullet drop if theyare using a BDC on their scope.

However they wouldn`t be able to dial in this effect even more so with iron sights.

[dunganick]

I see what you`re getting at but remember that most people are shooting at a distance they are comfortable with,say 300m and for longer shots,say 600m,they may be able to dial in the bullet drop if theyare using a BDC on their scope.

However they wouldn`t be able to dial in this effect even more so with iron sights.

 

im not certain this would make much difference, there are loads of other things i would imagine would become part of the equation.

 

Say for instance you didnt have your scope level.... yet say at 100 yards it was zero'd with the cross hairs level but the gun on a tilt. Now the barrel is very slightly shooting from one side into the POA... yet at 200 yards sureley it will now be shooting very slightly past the POA (starting to a think a digram is in order)

 

So at 1000 yards you might have an error of significance.

 

I would imagine most long range shooters would not rely on a balistics calculator to work out their zero, and at some point they would actually zero the rifle @ 1000yrds, which would remove this Coriolis effect as it would effect everything evenly. Hense you just zero to allow for it.

 

well that was about as clear as mud

[pin]

It made sense mate!

 

HD: I am pretty sure that a) they do know and compensate for it or don't know and call it windage

 

Either way it gets dialed out by the scope or holding into or out of "wind" First shot you take you look through the spotting scope and see POI, then adjust from there, which assuming you don't move means you have either dialled out the effect or compensated for it.

 

The effect is proportional to the mass (more mass more acceleration due to the effect), it also depends on the direction the shot travels in, in relation to the axis of rotation of the earth. If it is parallel to the axis of rotation (say due north) then the effect is almost nil (if it was say due east or due west, it would have more of an effect).

 

Interesting stuff (sound fx: pigeonwatch falls asleep at the back of the class)