I recently shot a local match and had no issues hitting what I aimed at when I did my part. Until a 100-200 yard troopline with a decent 6 o'clock tailwind. I rolled a donut on that stage and when I finished the spotter told me all my shots were considerably low. Next stage without the tailwind was not a problem with same dope calculations. I have looked and found nothing conclusive on this. Zermatt RimX with 18 in Benchmark barrel shooting CenterX capable of sub MOA at 100 yds for reference.
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Calculating tailwind ballistic effect
- Thread starter ackley264
- Start date
Were both stages just supported prone? I've donuted a stage almost because the position had me looking through the scope at a slight angle and I wasn't parallax free so I ended up shooting over everything.
This is all fine and dandy theory, but every bullet will have different deflection due to MV. Your gonna have to shoot and dope the wind. Sorry but there is no easy button on this one. @Jack Master and @lowlight will no doubt have some additional color to add. And oh, what if I’m using a LH twist?
Those charts are close with centerfire rifle, but I have experienced the same thing as the OP with 22LR. Both occasions the wind was over 17mph, seems like 15mph and under, no issues, it is just backwards from what we are told to expect.
I have no answers for the OP, when it first happened, I assumed the bullet was high enough to get into another higher, stronger wind pattern, but given max ordinate is under 50" to 300 yards, that makes no sense.
That all is all BULLSHIT BENCHREST trying to manage the offset of a hair, which may or may not appear for them
Practical shooting will not apply
Unless terrain is moving the wind under or down on the bullet the chart above is an absolute waste of everyone‘s time. You should be banned for posting misinformation
We have shot in 45MPH head winds among various other winds, and those deflection arrows are not right
In 45 MPH hit our 600 yard .2 tall truing bar with a 6mm
And before you play the AJ game, I turn it off... we zero it out.
We shoot in wind, lots of wind, more wind than you, trust me
There is NO calculation necessary
The only way this works is if the wind gets UNDER the bullet and is forced up, the whole pressures, blah, blah, blah, are fake
It's guys thinking they are too smart and know something they don't... ignore and throw that bullshit benchers wind chart away
Practical shooting will not apply
Unless terrain is moving the wind under or down on the bullet the chart above is an absolute waste of everyone‘s time. You should be banned for posting misinformation
We have shot in 45MPH head winds among various other winds, and those deflection arrows are not right
In 45 MPH hit our 600 yard .2 tall truing bar with a 6mm
And before you play the AJ game, I turn it off... we zero it out.
We shoot in wind, lots of wind, more wind than you, trust me
There is NO calculation necessary
The only way this works is if the wind gets UNDER the bullet and is forced up, the whole pressures, blah, blah, blah, are fake
It's guys thinking they are too smart and know something they don't... ignore and throw that bullshit benchers wind chart away
When you have a crosswind, you can see a vertical component of it, depending on the speed and terrain, but it's not nearly as big as people think. Its super small.
What we have seen is, you need about 12MPH over your zero wind. So If you zeroed in 6 MPH you would need an 18MPH wind to start to see a need to adjust your elevation with any repeatability. It's a lot more inconsistent than you might imagine.
Terrain is the biggest factor, even small stuff can have an effect if the wind can get under the bullet, while it is moving up. Those are small, specific localized changes. It will happen here, not there, over there, but not next to this ... weird stuff.
If you are on a manicured flat range somewhere shooting 600 -800 yards you are not seeing the vertical unless the winds go really big. Even then it might be a .2 change at the most. Most plates can suffer .2
And like noted above, we have Left Hand twist barrels, I run them a lot so you can mechanically cancel out any variations you might want to mention
What we have seen is, you need about 12MPH over your zero wind. So If you zeroed in 6 MPH you would need an 18MPH wind to start to see a need to adjust your elevation with any repeatability. It's a lot more inconsistent than you might imagine.
Terrain is the biggest factor, even small stuff can have an effect if the wind can get under the bullet, while it is moving up. Those are small, specific localized changes. It will happen here, not there, over there, but not next to this ... weird stuff.
If you are on a manicured flat range somewhere shooting 600 -800 yards you are not seeing the vertical unless the winds go really big. Even then it might be a .2 change at the most. Most plates can suffer .2
And like noted above, we have Left Hand twist barrels, I run them a lot so you can mechanically cancel out any variations you might want to mention
Some of the more experienced shooters say that a tail wind does cause rimfire to dive
I've experienced this with certerfire definitely out around 800 yds. Just seemed to be the opposite effect with rimfire
You mis-dialed your dope for that stage. 1. ALL your shots... 2. Zeroed stage. 3. Next stage was NOT a problem. It's the only logical answer if your parallax was correct and you weren't in a odd/off centered position. Assuming you're shooting 1 MOA+ targets, which are generally supported in a vertical fashion, meaning you could still hit a strap/stand, etc. There's no way the wind shorted you that much.
I'm a numbers guy so you know where I'm going with it.
Bullet speed is probably 900feet per second if you are on the slow end.
Wind speed at 20 mph = 29.33 feet per second.
Some shooters like to think, because of the tail wind, you bullet will fly faster and you impact the target higher than anticipated. To anticipate how high this might be they like to change thier muzzle velocity by the ~30 feet per second faster for a 20 mph wind. True is you bullet still exits you barrel at the 900 feet per second and is immediately slowing down due to initial bullet drag, but as it flys to the target has marginally less bullet drag due to the wind. The equivalent difference in feet per second is is closer to 10%-20% of the wind speed. (3-6 feet per second in this example and well within ammunition SDs)
1. If you are missing from a tail wind it should be high, not low.
2. Did anyone else in your squad have this trouble? If everyone else ran thier normal dope and hit targets shows your data or shooting was the issue, not the wind. Look at the match scores and see how other shooters did on this stage too.
I'm tend to agree with Jeff's dope above. Something else was off in your shooting process or we have bad information about the situation. wrong data, distance, parallax, bad RO spotting (seeing your splash 30 yards past the target which looks low?)
To me its most likely the wind was not at 6:00 but possibly switching from 5:30 to 6:30 or from one of them constant and you could have been missing just left or right. A 12:00 or 6:00 wind condition is the hardest to shoot in because a very small switch changes which direction you bullet drifts.
Before we blame the bullet or gear we have to really look hard at the environment and the shooter. They are usually the source of errors long before the system.
Bullet speed is probably 900feet per second if you are on the slow end.
Wind speed at 20 mph = 29.33 feet per second.
Some shooters like to think, because of the tail wind, you bullet will fly faster and you impact the target higher than anticipated. To anticipate how high this might be they like to change thier muzzle velocity by the ~30 feet per second faster for a 20 mph wind. True is you bullet still exits you barrel at the 900 feet per second and is immediately slowing down due to initial bullet drag, but as it flys to the target has marginally less bullet drag due to the wind. The equivalent difference in feet per second is is closer to 10%-20% of the wind speed. (3-6 feet per second in this example and well within ammunition SDs)
1. If you are missing from a tail wind it should be high, not low.
2. Did anyone else in your squad have this trouble? If everyone else ran thier normal dope and hit targets shows your data or shooting was the issue, not the wind. Look at the match scores and see how other shooters did on this stage too.
I'm tend to agree with Jeff's dope above. Something else was off in your shooting process or we have bad information about the situation. wrong data, distance, parallax, bad RO spotting (seeing your splash 30 yards past the target which looks low?)
To me its most likely the wind was not at 6:00 but possibly switching from 5:30 to 6:30 or from one of them constant and you could have been missing just left or right. A 12:00 or 6:00 wind condition is the hardest to shoot in because a very small switch changes which direction you bullet drifts.
Before we blame the bullet or gear we have to really look hard at the environment and the shooter. They are usually the source of errors long before the system.
A pure tailwind is very rare.
What usually happens is a switching 5-7 o’clock. Enough to push the bullet off for a miss.
Combine that with hard to see Rimfire bullets and/or not great spotter (most people aren’t that good at spotting, especially if not directly behind shooter)……and you’re in for a rough stage.
As long as you checked parallax, like actually moving your head around, that should be fine. But parallax is larger the closer the target, so Rimfire is especially vulnerable.
As well as weird things like lighting. A switchy wind with some weird sun in your face + across the target at a weird angle = rough day.
What usually happens is a switching 5-7 o’clock. Enough to push the bullet off for a miss.
Combine that with hard to see Rimfire bullets and/or not great spotter (most people aren’t that good at spotting, especially if not directly behind shooter)……and you’re in for a rough stage.
As long as you checked parallax, like actually moving your head around, that should be fine. But parallax is larger the closer the target, so Rimfire is especially vulnerable.
As well as weird things like lighting. A switchy wind with some weird sun in your face + across the target at a weird angle = rough day.
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Thanks, interestingThe following ballistics charts are generated by Gundata.org ballistics calculator. For purposes of comparison, the ammo is CX and the zero range is set at 0 yards for both.
The first has a 0 mph tailwind, no crosswind. The second has a 30 mph tailwind, no crosswind.
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A couple numbers in these charts are not following the laws of physics. How is a bullet that is being "pushed" by the wind going to have less velocity than a bullet with no wind?The following ballistics charts are generated by Gundata.org ballistics calculator. For purposes of comparison, the ammo is CX and the zero range is set at 0 yards for both.
The first has a 0 mph tailwind, no crosswind. The second has a 30 mph tailwind, no crosswind.
From the tables above at 500yds
no wind = 671fps
30mph "Tail" wind = 640 fps (this should be faster than the no wind situation.)
Also, the time of flight is longer with a tail wind??? I don't think so.
In every single other ballistic program I have tried today (JMB, Hornady, Applied ballistics) I could not get these results. After playing with the gundata.org ballistic app it seems to me they have thier angle of wind direction wrong. Zero degrees should be a head wind and 180 degrees is a tail wind. This would also match the nomenclature of the rest of of the ballistic app worlds with 0 = head and 180 = tail. (not to mention every single compass I have ever read) Or, gundata.org knows something the app developers don't know??...??? (I wouldn't put my chickens in the that basket)
Just saying. This does not add up.
This is not "BULLSHIT BENCHREST" and my charts are accurate. They may not be able to manage the offset of a hair's diameter like you said, but they're adequate enough to manage under 0.1" if you're lucky and/or skilled enough to have a RFBR rifle at or above the 80th percentile.
Practical shooting with my charts will most definitely apply to RF BR, but only at 50yds/50M. You're trashing me for something the charts were never supposed to be used for by interjecting CF and/or longer distances.
I'm also not one of those guys who thinks they know something they don't, and I only think I know something better than others after exhaustive research backed up by over 40 years of competitive shooting and testing.
I strongly suggest you read the thread from which the charts originated because it will provide the context needed to fully understand them.
A Wind Chart
I've been messing around with designing a wind rose or chart that actually describes where the bullet impacts rather than those in the past which only show an exaggerated flight of the bullet with no info for wind velocity. The problems are creating a chart that's intuitive, but not cluttered...
www.rimfireaccuracy.com
I probably shouldn't say this, but I'm more than a little disappointed a moderator would attack me for no reason I can think of and I'm not even certain I want to know why because I don't plan on contributing anything more.
Landy
All due respect, he didn’t attack you. He was “attacking” your post. Don’t make it personal because he disagrees with your opinion. I don’t agree with it either. I don’t measure misses or offsets in inches because no one can measure that. I use the reticle and make corrections. I think this theory is antiquated and whether you are BR shooter or a field shooter, knowing your dope is all that matters.This is not "BULLSHIT BENCHREST" and my charts are accurate. They may not be able to manage the offset of a hair's diameter like you said, but they're adequate enough to manage under 0.1" if you're lucky and/or skilled enough to have a RFBR rifle at or above the 80th percentile.
Practical shooting with my charts will most definitely apply to RF BR, but only at 50yds/50M. You're trashing me for something the charts were never supposed to be used for by interjecting CF and/or longer distances.
I'm also not one of those guys who thinks they know something they don't, and I only think I know something better than others after exhaustive research backed up by over 40 years of competitive shooting and testing.
I strongly suggest you read the thread from which the charts originated because it will provide the context needed to fully understand them.
A Wind Chart
I've been messing around with designing a wind rose or chart that actually describes where the bullet impacts rather than those in the past which only show an exaggerated flight of the bullet with no info for wind velocity. The problems are creating a chart that's intuitive, but not cluttered...
I probably shouldn't say this, but I'm more than a little disappointed a moderator would attack me for no reason I can think of and I'm not even certain I want to know why because I don't plan on contributing anything more.
Landy
I guess if you consider a 22LR bullet at 250 yards going 530 mph faster than the wind being pushed. I think at some point, BC, spin, velocity vs physics must play.
I shoot in a lot of tail winds, wind here is predominantly from the SW, range I shoot points NE. Centerfire bullets coming from a 2900 MV start out at 1950 mph faster than a 20mph wind, you subtract the estimated carry from an entered 20mph wind in your firing solution, you will hit low on a structureless range.
It Applies, it applies.... to Rimfire, maybe, if you can measure it to .1" from 50m away, genius line
And I am not a moderator I OWN the place. the Site Owner disagrees with your post.
I don't know who you are to attack you, I attacked what you wrote, which I disagree with, unless you are doing Rimfire Benchrest inside 100 yards, ya, you might be able to anecdotally show some of that, but not all of that so you fill in the rest of the blanks
Perfect, now post a video of you putting it in practice on the fly
And I am not a moderator I OWN the place. the Site Owner disagrees with your post.
I don't know who you are to attack you, I attacked what you wrote, which I disagree with, unless you are doing Rimfire Benchrest inside 100 yards, ya, you might be able to anecdotally show some of that, but not all of that so you fill in the rest of the blanks
Perfect, now post a video of you putting it in practice on the fly
And the moment you have someone talking about a Headwind or Tailwind and not acknowledging the real problem vs this phantom elevation issue, the real horizontal component
Headwinds and Tailwinds never are, true head or tail, as in 12 O Clock or 6 O Clock, it, like all wind, moves, and the misses are not high or low but left or right because there is always side elements to it.
And the key, it switches, on my range. , constantly, one round could be held left, the next round held right, then back to left, it might be, left, left, right, center, left, right, left, right, right, left, right, left, center, left, right... all in one minute
So the idea in these winds you are calculating based off a .1" measurement is a joke, or at least the internet version of a bad plan.
Headwind and tailwind talk is amateur hour
Headwinds and Tailwinds never are, true head or tail, as in 12 O Clock or 6 O Clock, it, like all wind, moves, and the misses are not high or low but left or right because there is always side elements to it.
And the key, it switches, on my range. , constantly, one round could be held left, the next round held right, then back to left, it might be, left, left, right, center, left, right, left, right, right, left, right, left, center, left, right... all in one minute
So the idea in these winds you are calculating based off a .1" measurement is a joke, or at least the internet version of a bad plan.
Headwind and tailwind talk is amateur hour
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It seems that a good point has been raised with regard to whether zero degrees should be a headwind or tailwind.
There doesn't seem to be uniformity between online calculators as to whether zero degrees is head or tail wind. I looked at only a few others that came up when I used Google. It may be that the majority use zero degrees to represent a headwind, but it's worth noting that gundata.org is not the only one to use zero degrees for a tailwind.
I don't have a horse in this race with regard to ballistics calculators.
Out of curiosity, what kind of rifle would you have to have to be above that "80th percentile" line?
That sounds like a video game cheat code from 30+ years ago.
Unlimited ammo. Contra. Up down up down left right left right A B B A.Out of curiosity, what kind of rifle would you have to have to be above that "80th percentile" line?
That sounds like a video game cheat code from 30+ years ago.
Funny the shit you remember from childhood
I appreciate the input from all. I brought up the tailwind concept based upon several very experienced rimfire shooters input. I understand shooting in wind. I've grew up shooting in western Nebraska and now shoot a lot down south of Oklahoma City 300-1400 yards. As for rimfire, I shoot out to 550, which velocity SD can cause more headaches than wind. I honestly am baffled as to the cause of the misses I had and will just need to shoot more in those conditions I guess.
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