Coriolis

[Dr Ray]

Shooting long distance

 

[thriller]

Is that the same as the coorsiolis effect where you have had a couple too many silver bullets and can't hit the broad side of a barn?

 

[Dr Ray]

Shooting long distance

Although not much to do w hunting I have always wondered why manufacturers make right hand twist barrels for the northern hemisphere.
I think the Lee Enfield 303 British was the only barrel make w left hand twist.
I live in the Southern Hemisphere so right hand twist suits us for long distance shooting.
This coriolis effect won't affect shooting at normal hunting ranges.
Competition shooting at long distance does take into consideration spin drift, coriolis effect, Magnus effect and so on.

 

[Dr Ray]

Is that the same as the coorsiolis effect where you have had a couple too many silver bullets and can't hit the broad side of a barn?

Obviously

 

[CAustin]

Learned something new. Never heard this before!

 

[Shootist43]

Coriolis is just one more of the lesser known factors involved in long distance shooting. Nathan Foster addresses it and many other "environmental effects" as he calls them in his book titled The Practical Guide To Long Distance Shooting on pages 166 and following. I've referenced Nathan Foster's writings in numerous posts to AH. For shots in the 1200 to 1400 yard range a click or two scope adjustment is required to compensate for Coriolis. For distances beyond that Coriolis is of greater concern.

Charlie, just for the record, you cannot use Coriolis as an excuse for a less than perfect shot on your Hippo! LOL

For those of you that would like to take a peek at what Nathan Foster has to offer, here is a link to his website.
http://www.ballisticstudies.com/

Nathan Foster has written 5 books dealing with different aspects of long range hunting. They make for some interesting reading, especially during those long flights to Africa or those cold winter nights when there is nothing good on television.

 

[CAustin]

No excuses then Art!

 

[ScottG]

Only effects you east to west. Aim high shooting east, the earth rising to you. Aim low shooting west the earth falling away from you.

 

[lcq]

Coriolis is just one more of the lesser known factors involved in long distance shooting. Nathan Foster addresses it and many other "environmental effects" as he calls them in his book titled The Practical Guide To Long Distance Shooting on pages 166 and following. I've referenced Nathan Foster's writings in numerous posts to AH. For shots in the 1200 to 1400 yard range a click or two scope adjustment is required to compensate for Coriolis. For distances beyond that Coriolis is of greater concern.

Charlie, just for the record, you cannot use Coriolis as an excuse for a less than perfect shot on your Hippo! LOL

For those of you that would like to take a peek at what Nathan Foster has to offer, here is a link to his website.
http://www.ballisticstudies.com/

Nathan Foster has written 5 books dealing with different aspects of long range hunting. They make for some interesting reading, especially during those long flights to Africa or those cold winter nights when there is nothing good on television.

Nothing good on TV now that Wanted Ted or Alive is gone

 

[lcq]

Coriolis is what Robin Williams would call a fart in a hurricane. Wind (which is never consistent) and stable shooting platform (good luck in the field) would have a far greater effect on bullet trajectory.

 

[Tim Beahan]

Actually, it will also affect shots bearing 0 and 180 degrees, but in a horizontal direction, as your target is moving with the earth while your projectile is in flight.

 

[ChrisG]

Actually, it will also affect shots bearing 0 and 180 degrees, but in a horizontal direction, as your target is moving with the earth while your projectile is in flight.

I don't think that is as big of a deal as the bullet will be moving along with the earth as it started at ground level geocentric speed already moving east to west. Shooting east has essentially the same effect as slightly decreasing range as the target is also moving toward the bullet. This is the same as increasing its localized relative velocity, causing it to hit high. Westwardly the opposite is happening. This is the same reason spacecraft always launch to the east. They are using Coriolis to increase their orbital speed relative to earth so as to burn less rocket fuel to reach orbital velocity. On a north/south shot, the bullet is already moving at the same relative velocity east to west as the target so Coriolis is negated. Besides that, as stated above, spin drift and wind are going to almost always rule out Coriolis as the reason you missed.

 

[Ray B]

At the equator the ground is moving at about a thousand miles per hour. at the poles it rotates with one turn in 24 hours (actually slightly less because each turn has a little added to it for Earth movement relative to the Sun). The result is a push on something tens to cause it to move a right angles to the push. This is why a strong wind blowing North to South will cause the surface water along the Mexico/California/Oregon/Washington/BC coastline to push out into the ocean. This causes a vacuum which brings subsurface water up to the beach and along with it, plants and animals which then become food.

 

[Pancho]

So I should site in 1" high when hunting North of the equator and 1" low when hunting in the South.

 

[Red Leg]

Jeez - we actually worry about that firing field artillery out beyond twelve kilometers or so - with a rifle - not so much.

 

[sierraone]

Don't think I need to worry about my 200 yards and less shots!

 

[Ray B]

So I should site in 1" high when hunting North of the equator and 1" low when hunting in the South.

No, it's not a high or low; it's a side push, so north of the equator you'd adjust to one side and south of it you'd adjust to the other, but I forget which way is which. Best to have a spotter, fire one shot, see impact, adjust and hit with the second.

 

[sheephunterab]

A factor that needs to be considered for shooting in excess of 1,000 yards for sure. I'm not certain that the rifling twist and associated spin drift was ever purposeful to counteract Coriolis effect in North America but who knows I guess.

 

[stug]

It is not just north or south of the equator, it is also the direction of the shot. It can increase or decrease elevation as well as windage. But at normal hunting distances has no real effect. Past 600 ish yards it has a bit of an effect, past 1000 yds it has more of an effect. Most good ballsitic apps have a coriolis effect function.

 

[Rob404]

Isn't there a Scope I could purchase for 5-6 thousand that will automatically correct for this?