Wind rose

[gunsandgunsmithing]

I post about group shapes on here a fair bit and how I use them to read tune as well as conditions. Many on here are already familiar with these but I haven't seen it posted in quite a while. They are a useful tool. I hear a lot of talk about full value and half value, etc. The reality is that crosswinds also have a vertical component to them depending on rh or lh twist. There are very, very few LH twist bbls on this side of the pond or anywhere in the accuracy game but if you were to have one, everything is just opposite from the chart.

You have to test but as a general rule, I find that a true crosswind(full value) has about 1/3rd as much vertical as horizontal to it...without getting into spin drift and other factors.

Just a good guide here. This is why you see me post about wind generally NOT creating groups diagonally up and to the right. The other way, yes,(up and left). So, even with a one hole group, you can use this to help with how well tuned the rifle is or isn't. Especially so if the groups around it are predictable but that gets deeper than intended for this thread.

 

[gunsandgunsmithing]

Look at the vertical induced from 11-1 o'clock, 10-2 and of course 12-6 o'clock!

 

[spike-55]

I found this neat little decal from ballisticsjunkies.com. It’s really handy to attach to your loading boxes or other stuff for reference
Stan

 

[gunsandgunsmithing]

It's ok with me but I sure hear a lot from people that conflicts with this. Hopefully it was of value to some. It's of great value to me, especially when tuning. In a match, it may save you because it explains why that last shot went where it did and why the next one will too, vs blaming tune or equipment etc. It builds confidence, even a miss, if you know it went right where it should.

 

[jimmymac]

I have one of those stickers plastered on the rear of my rest.

 

[JFrank]

I keep this one handy

 

[Mulligan]

The 12/1 and 6/7 change has bit me in the backside more than once!
You get a little 1030-1130 change and your hanging in there, along comes a 1230-1 OUCH!!!

One of my fellow shooters came along after an ugly 1:30 switch and says...... why don't you grow a pair and move your point of aim when it does that????
Well SHOOOOOOT.
CW

 

[JFrank]

I can still get high right impacts at my tuner range, I think it’s a second push or swirl down there hiding.

 

[gpoldblue]

I post about group shapes on here a fair bit and how I use them to read tune as well as conditions. Many on here are already familiar with these but I haven't seen it posted in quite a while. They are a useful tool. I hear a lot of talk about full value and half value, etc. The reality is that crosswinds also have a vertical component to them depending on rh or lh twist. There are very, very few LH twist bbls on this side of the pond or anywhere in the accuracy game but if you were to have one, everything is just opposite from the chart.

You have to test but as a general rule, I find that a true crosswind(full value) has about 1/3rd as much vertical as horizontal to it...without getting into spin drift and other factors.

Just a good guide here. This is why you see me post about wind generally NOT creating groups diagonally up and to the right. The other way, yes,(up and left). So, even with a one hole group, you can use this to help with how well tuned the rifle is or isn't. Especially so if the groups around it are predictable but that gets deeper than intended for this thread.

View attachment 1497215

This is under the assumption that the wind AND the bullet path are both parallel to the ground. Sometimes the wind is but never the bullet. The bullet is always fired from the bore axis upward to and beyond the line of sight in an upward arc. That's why this is 'only' a guide. Angling winds especially can really raise questions.
Good luck and stay safe.

 

[gpoldblue]

I can still get high right impacts at my tuner range, I think it’s a second push or swirl down there hiding.

I get high/rights at my range too......I've discerned the cause to be angling winds Depends on where on the range the push is coming from. Most of the time the wind force is not the same all the way from the bench to the target. Depends on where the dominant force is. Another example of the importance of wind flags and wind flags are not 100% and are always late,but they're the most reliable we have these days.

 

[avidflyer]

Always thought from reading in the past those are more tailored to rimfire. Not that some effects won't be similar, but those were more for rimfire.

 

[gunsandgunsmithing]

When I get high rights I can typically attribute them to tune. The chart doesn't account for thermals etc, so they are still possible. Mirage and gun handling can both do it, as can tune. There are always exceptions but I find it to be pretty accurate.

 

[gunsandgunsmithing]

The 12/1 and 6/7 change has bit me in the backside more than once!
You get a little 1030-1130 change and your hanging in there, along comes a 1230-1 OUCH!!!

One of my fellow shooters came along after an ugly 1:30 switch and says...... why don't you grow a pair and move your point of aim when it does that????
Well SHOOOOOOT.
CW

This! I suffer from the same thing. Sometimes it's tough to put the reticle where it really needs to be. Not much makes me madder at myself that having 3 line lickers, just out and all having the same relative poi. That's on the shooter and what you just said. Of course, if I put the crosshairs out there, it'll change and go right where I was holding!

 

[gunsandgunsmithing]

Always thought from reading in the past those are more tailored to rimfire. Not that some effects won't be similar, but those were more for rimfire.

It's quite common to see that chart or similar pasted to the front rest or somewhere, at cf matches. I can't really imagine the dynamics that would only make it apply to rf.

 

[6ShotsOr5?]

Timely post for me, a few of those 12/1 switches cost me in a match two days ago. Just went shopping for some of those stickers. Thank to @gunsandgunsmithing for this thread.

 

[gpoldblue]

Timely post for me, a few of those 12/1 switches cost me in a match two days ago. Just went shopping for some of those stickers. Thank to @gunsandgunsmithing for this thread.

Yeah...I been caught "speedin'" a number of times too. If the condition holds long enough,I shoot a sighter and dope the shot. Fish tailing winds are hard to deal with either head or tail winds.
Good luck and stay safe.

 

[dannyjbiggs]

Always thought from reading in the past those are more tailored to rimfire. Not that some effects won't be similar, but those were more for rimfire.

Concur. When I first saw the attached diagram about a decade ago, I called the number and spoke to a Mr. Tom Myers. Advised him that I was an FO shooter and asked if he would mind if I made some adjustments to his diagram strictly for my use. Gave me the go ahead and stated the wind vector was primarily for rimfire,

Dan

 

[gunsandgunsmithing]

Concur. When I first saw the attached diagram about a decade ago, I called the number and spoke to a Mr. Tom Myers. Advised him that I was an FO shooter and asked if he would mind if I made some adjustments to his diagram strictly for my use. Gave me the go ahead and stated the wind vector was primarily for rimfire,

Dan

Dan, did he happen to say why one would be different than the other? That's what I'd have trouble understanding, is how a rh twist bbl from a cartridge with the primer at the rim vs a cf with the primer in the middle, would go a different direction due to wind. Other charts are out there and all are at the least, very similar. Can't and won't say that is right or wrong except to say that my cf rifles do very much follow the chart.

The point of the chart should not be diminished unless it can be verified that rf bullets go a different direction in wind than cf. That chart or one similar is a valuable tool to understanding our hits and our misses and judging tune. I'd be interested in what changes you made to yours and why. I'm sure it was likely based on shooting and that's the main thing, for sure but I'd hate for the tool to be discredited without something solid because it's so valuable to learning.

It's been accepted for a long time and I'd be interested in how he went about making his version too.

 

[gunsandgunsmithing]

Here's one explanation. In a nutshell, the bullet points slightly into the wind dependent upon direction of rotation. This causes a high pressure side and a low pressure side. The difference in pressures creates more or less lift. At least that's my understanding. I'm sure there are differences in the AMOUNT of lift between rf and cf, but not in direction of lift for respective direction of spin of the bullet. I don't use the chart to tell me how far the bullet will move but rather, the direction and how much is relative. Otherwise, I see so reason cf would be different from rf. Interesting read either way...

4.3 Turning of a Bullet to Follow a Crosswind and Resulting Deflections - Sierra Bullets

www.sierrabullets.com

 

[avidflyer]

Here's one explanation. In a nutshell, the bullet points slightly into the wind dependent upon direction of rotation. This causes a high pressure side and a low pressure side. The difference in pressures creates more or less lift. At least that's my understanding. I'm sure there are differences in the AMOUNT of lift between rf and cf, but not in direction of lift for respective direction of spin of the bullet. I don't use the chart to tell me how far the bullet will move but rather, the direction and how much is relative. Otherwise, I see so reason cf would be different from rf. Interesting read either way...

4.3 Turning of a Bullet to Follow a Crosswind and Resulting Deflections - Sierra Bullets

www.sierrabullets.com

I just took a look at this on my phone, and isn't the description Sierra is giving you 100% opposite of the chart for a right hand barrel? Granted looking on a small phone screen.

Barrel Twist Crosswind	Crossrange	Vertical
Direction	Deflection	Deflection
RH L to R	Right	Upward
RH R to L	Left	Downward