The Magnus Effect!

[M14AMU]

http://www.youtube.com/watch?feature=player_detailpage&v=23f1jvGUWJs

 

[KMart]

My PMI at Edson Range never told me about this stuff!

 

[M14AMU]

My PMI at Edson Range never told me about this stuff!

KMart

There's a reason for that!

If you've read my old deceased friend Carlos Hathcock's book he stated in it:

"There aren't enough upper echelon men in the military today that understand marksmanship to make up a baseball team!"

 

[jerrschmitt]

My PMI at Edson Range never told me about this stuff!

Never mentioned because you aren't shooting tennis balls. As for rifle projectals, no effect at ranges under around 1000 yards. Over that we call it spin drift.

Or maybe I'm totally wrong.

 

[Keith Glasscock]

Spin drift and aerodynamic jump.

Both have effect at 600 and greater, but it isn't that much...

 

[xdeano]

oh fun fun. Now just add a touch of horizontal and/or vertical wind to the spin drift and lets have some fun.

Gotta love physics.

xdeano

 

[Win94ae]

My PMI at Edson Range never told me about this stuff!

Never mentioned because you aren't shooting tennis balls. As for rifle projectals, no effect at ranges under around 1000 yards. Over that we call it spin drift.

Or maybe I'm totally wrong.

Yes, you are wrong. Gyroscopic drift (Spin drift) and the Magnus effect are two different things.

I'd also like to note that Gyroscopic drift can be noticed at short ranges also. For example; a 180gr SP shot from my right handed rifling 30-06, drifts 3 inches more to the right at 400 yards than it does at 100 yards. If I use a 220gr projectile, it drifts 4 inches more than the 180gr at 400 yards.

 

[CaptainMal]

So if I could get a seam on a bullet, turn the barrel sideways so it spins counterclockwise, reduce the powder charge and make a boomerang bullet.

All so simple to me.

 

[Nomad47]

Spin drift for most of the heavy-for-caliber bullets is ROUGHLY equal to a 1 MPH left to right wind.

 

[jerrschmitt]

Yes, you are wrong. I'd also like to note that Gyroscopic drift can be noticed at short ranges also. For example; a 180gr SP shot from my right handed rifling 30-06, drifts 3 inches more to the right at 400 yards than it does at 100 yards. If I use a 220gr projectile, it drifts 4 inches more than the 180gr at 400 yards.

I think you have something else going on other than gyroscopic drift if your windage is that much at 400 yards.

 

[Win94ae]

Yes, you are wrong. I'd also like to note that Gyroscopic drift can be noticed at short ranges also. For example; a 180gr SP shot from my right handed rifling 30-06, drifts 3 inches more to the right at 400 yards than it does at 100 yards. If I use a 220gr projectile, it drifts 4 inches more than the 180gr at 400 yards.

I think you have something else going on other than gyroscopic drift if your windage is that much at 400 yards.

You had the two effects mixed-up, yet you are sure my explanation for the deviation is incorrect... you offer no reasoning behind your conclusion.

Do you also disagree with this statement?

Spin drift for most of the heavy-for-caliber bullets is ROUGHLY equal to a 1 MPH left to right wind.

Because I see about 40% less deviation with my 180gr SP.

It is accepted science, recordable and repeatable.

 

[jerrschmitt]

Yes, you are wrong. I'd also like to note that Gyroscopic drift can be noticed at short ranges also. For example; a 180gr SP shot from my right handed rifling 30-06, drifts 3 inches more to the right at 400 yards than it does at 100 yards. If I use a 220gr projectile, it drifts 4 inches more than the 180gr at 400 yards.

I think you have something else going on other than gyroscopic drift if your windage is that much at 400 yards.

You had the two effects mixed-up, yet you are sure my explanation for the deviation is incorrect... you offer no reasoning behind your conclusion.

Do you also disagree with this statement?

Spin drift for most of the heavy-for-caliber bullets is ROUGHLY equal to a 1 MPH left to right wind.

Because I see about 40% less deviation with my 180gr SP.

It is accepted science, recordable and repeatable.

Lets take this a point at a time. I'm still a little new to all this science stuff.

Roughly equal to a one MPH wind. According to my log book for my .243 Ackley Improved shooting 105 AMAX bullets, that would be about .2 MOA at 400 yards or about .8 inches

Using my .308 with 175 SMK it goes up to .3 MOA at 400 yards. (1.2 inches)

Now I have never been able to judge a 1 MPH wind even back in my younger days when I actually shot real live matches. Is that wind 6 MPH or 7 MPH? Nope, can't tell you. So I say that it don't matter at short range. I have more problems trying to figure out if that wind is 6MPH or 7 MPH and is it coming from 9 O”Clock or 9:45 and is it AM or PM.

At 400 yards you're reporting 1.3 MOA of drift. What wind meter are you using? Maybe a better bullet? Maybe your scope doesn't track plumb.

My whole point is that Spin Drift, Magnus, and the phase of the moon doesn't matter to MOST shooters because the effects of wind over distance null it out.

 

[Nomad47]

You guys are missing my point. You don't have to know what a 1 MPH wind feels like or the difference between 6 or 7 MPH wind.
Here is what I meant. If you want to cancel the effect of spin drift, put scope correction in for a 1 MPH wind. OR if you want to know how far spin drift will cause your bullet to drift, put a 1 MPH wind into a ballistics program.

A friend and I shoot 8" steel at 875 yards today. We had a very light breeze blowing from right to left, so we didn't put in any windage correction - and hit the steel. The light breeze cancelled spin drift.

 

[Nomad47]

And I wouldn't call a 180 grain bullet a heavy-for-caliber bullet in 30 caliber. I was talking bullets that require a faster than average twist rate. Like an 8 twist in a 6mm caliber or a 9 twist in a 7mm caliber.

Win94ae, are you saying a 220 grain bullet in your 30-06 has 7" of spin drift at 400 yards?

 

[jerrschmitt]

You guys are missing my point. You don't have to know what a 1 MPH wind feels like or the difference between 6 or 7 MPH wind.
Here is what I meant. If you want to cancel the effect of spin drift, put scope correction in for a 1 MPH wind. OR if you want to know how far spin drift will cause your bullet to drift, put a 1 MPH wind into a ballistics program.

A friend and I shoot 8" steel at 875 yards today. We had a very light breeze blowing from right to left, so we didn't put in any windage correction - and hit the steel. The light breeze cancelled spin drift.

I understand your point. I'm just saying that combined with what ever wind is out there, it don't matter because I can't (and most can't) Judge wind that close.

You are on the 800 yard range, Say you have a wind from 3 O'Clock which I judge to be at 5 - 7 MPH. I call it as a 6 MPH and don't correct for spin drift. The guy on my right might call it a 5 and the guy on my left might call it a 7. Even if all of us corrected for spin drift, we'd still be in the same boat.