Too windy for load testing?

[Tom68]

So I had planned to go to the range today to test some loads I have assembled but was disappointed to check the weather and read the forecast which calls for 15 mph wind. Obviously perfect weather conditions are best for isolating load factors and comparing them, but weather is seldom perfect.

So, how windy is too windy to even bother with evaluating test loads? Not talking about shooting in general as doping wind is an important skill. Really just curious what others think about load development testing under windy conditions.

[MarkCO]

If it is constant, just deal with it. Variable, that is rough and I won't do load development if the winds are not at least consistent. I have learned to take another gun when shooting 500 on out so i can at least practice. I do at least half of my load development at the 100 yard indoor midweek.

[reddog81]

I would be happy with a 15 MPH wind. Where I shoot that is about average.

What kind of distances are you shooting? I'm usually shooting at 100 yards so a 15 MPH wind is still going to be on the target without any adjustments. At 300 yards a 15 MPH wind becomes more of a nuisance.

Right now I'm more concerned about the cold. It's 2 degrees outside where I'm at.

[Unclenick]

It will make no difference if the wind is very steady. If it is gusting and running up and down or shifting direction, it causes differing amounts of bullet jump which takes some effort to correct for. Bullet jump due to side wind creates a drift up or down, depending which direction the wind comes from. This is the result of precession correcting the yaw of repose to turn the bullet into the wind, which it does by a net up and over motion for wind in the direction the bottom of the bullet turns toward, and dipping under and over to correct into wind moving opposite the direction that the bottom of the bullet is turning toward. The net result for a rifle with a right-hand twist barrel is a wind from the right moves the point of impact left and up, while a wind from the left moves the bullet right and down, with the amount of vertical proportional to the left or right wind vector velocity component. This means a wind varying in direction and velocity strings the bullets on a diagonal line, as below.



The steepness of the angle of that diagonal increases roughly as the logarithm of the gyroscopic stability factor of the bullet, so if you know the average stability factor, you can theoretically draw a vertical line anywhere in the target and then connect every hole center to that line with a diagonal line at the angle corresponding to the stability factor you have, then use the locations of the line crossings as "bullet holes" for the purpose of evaluating your ladder. I have only once gone to the trouble to do that using a load I already knew the ladder points for, and it seemed to work. I did not draw a vertical line, though; I just used one vertical edge of the target paper. I still got a vertical line cluster at the load sweet spot.

Conversely, once you have a reasonably good load, you can fire a group in a gusting wind and use the least squares fit line to establish the diagonal and deduce the stability factor if you want to. Or you can use that line just to determine the diagonal to use with the ladder shots and leave the specific stability factor out of it.

The easiest way to get the least squares fit line these days is to lay an X-Y grid over the target, locate the X and Y positions of each hole, put them into X and Y columns in Excel, select the columns and then the scatter plot graphing function to plot them and then select the data in the plot to Add Trendline, selecting the linear function with the Show Formula box checked. This will give you the least squares fit line and its formula. The angle will be arcsine of the slope, which is the part that multiplies X in the formula. If, say, the formula is 0.3X+n, then you know the line goes 0.3 inches up for each inch left (for a right-hand twist barrel) and -0.3 in down for each inch to the right. The arcsine of 0.3 is 17.5°, so that's the angle of your diagonal up from right to left, or -17° down from left to right. Either way, that's your angle for lining holes up with the vertical line.

[T. O'Heir]

A lot will depend on the calibre you're playing with. A .22 will get pushed around more than a 6mm or .30 cal. Otherwise, since your testing groups size only, you can adapt for a 15 mph wind. If like Nick says, it's consistent.
"...It's 2 degrees..." Kind of relative to one's location. It's -16C(3.2F) here with a 11 mph wind that gives us a wind chill to feel like -25C(-13F). S'friggin' cold.

[Tom68]

Wow Nick, wow. I actually had not considered the physics by which a person could formulate a predictive analysis on the effect of a crosswind on a speeding bullet.

It's about 45 here in the Deep South today with a nuisance drizzle. Forecast calls for clearing on Friday, so I'll plan for that before I go back to work next week.

Oh and to answer the questions, caliber is .308 Win with 168 gr bullets. I normally shoot test loads at 200 yards, although my range also has 100 and 300 yd lanes. 300 is a little far out to see holes in paper through my 24x scope, and I'm getting small enough groups these days that make it difficult to differentiate holes in the target.

[m&p45acp10+1]

Where I shoot the wind is almost always blowing 15mph plus. It moves the targets like sails on a ship.

[Road_Clam]

I do all my testing at 200 meters. I hate trying to test on a windy day especially in the colder months when the air is more dense. The wind drifting my shots is not really a concern as it's minimal. A more frustrating situation is the wind gusts blowing all my testing accessories on the ground, shaking my chrono, and my spotting scope and the potential dust. Calm days are perfect days to test and I try to plan accordingly !

[Unclenick]

Tom,

You can estimate the gyroscopic stability factor, s or GS, from the calculator on the JBM site based on Don Miller's modification of the Greenhill formula, or using Geoffrey Kolbe's site's twist calculator, which is based on Robert L. McCoy's old McGyro program and which gives stability factor vs twist rate on a plot.

[Slamfire]

I am going to say that a "steady wind" is an intellectual concept, not a physical reality. Wind is chaotic, and the higher the velocity of wind, the more chaos you are going to see on

I am quite certain the left to right movement on these targets were due to wind let off's that I did not pick up, because I was aiming and not scoping the wind. The day I shot these, it was windy, probably 10-15 mph, picking up, letting off, and changing direction.





A wind change of 10 mph will blow you out of the ten ring at any distance. In smallbore prone, a wind change of 5 mph will blow you out of the 10 ring. You will really see the effects of wind if you shoot Smallbore prone. I will do everything I can not to shoot in 3 O'C or 9 O'C winds because the take ups and let off's are brutal. Just a slight let up and baby, you are in the eight ring. Might as well pack up your gear and go home. And, wind is not constant nor linear. There are "dust devils" you don't see, but they come and go, and are not predictable. I have seen them on ranges where the firing point was elevated, you see what looks to be a circle of grass moving clockwise or counterclockwise in the field. When one of them runs over your target, the bullets moves in one direction at the front of the dust devil, and in the other direction when the dust devil pass over. Very confusing. I also believe there are "barrel roll" wind movements. The faster the wind flow, the more these chaotic events happen, and the worse their effect.

If you don't have time to shoot another day, then shoot. Might make a better wind reader out of you if you put out wind flags. I have been making my own. Home Depot has these 48" long, 30 caliber fiberglass driveway reflectors. Cut them in half with a dremel tool cutting disc. Use your grinder to make one end pointy. Then glue a 30 caliber something on the blunt end. I prefer cartridges with a rim, like 30-30 Winchester. Drill through the primer hole (after removing the primer). Stick a paper clip in the hole, attach to the paper clip a ribbon, and you have your own wind flag. Stick enough wind flags out so you can see the wind change direction. Shoot when everything is the same, all the way out. That will help, but will not fix rapid wind changes. There will be times when you are taking up the pressure and the whole range resets itself to something bizarre.


https://www.homedepot.com/p/Blazer-I...1ODM/202498049

[hounddawg]

Depends on the wind and the range in my opinion. On my home range most of the year we have mild consistent winds and I rely mostly on mirage. I load test in those conditions early in the day and even mid day the movement is predictable for the most part. Winters different, fishtailing winds all day combine with terrain features and the berms layout make windy day shooting a challenge. These are the times I shoot a proven load at steel while taking notes

[Fotheringill]

Scientific and technical answers aside, common sense tells us that a variable speed or variable direction wind is going to throw off the path of the bullet.

I am dying to go out Saturday to try some new powder. It isn't going to happen.

[Tsquared]

With a good spotting scope you can watch a bullet going down range. I have seen .223 jump all over due to wind gusts on a 500M range.

[RC20]

I mostly don't care. If I can keep the target upright I am good.

I can't shoot so good I can see it.

Limited to 100 yard so not as much an issue.

If I get something that looks good I just repeat and go back until the wind is calm.

I had not a clue of all the calculations you could do with all that.

I will pass, I make myself nuts enough.

[FrankenMauser]

I don't do load testing in crosswinds, but have occasionally still moved forward with testing with tailwinds.
My local range is oriented in line with the prevailing afternoon winds here, and the 50 and 100-yard rifle bays are very deep and very narrow, with tall, steep-sided berms. As long as the wind is moving in the 'normal' direction, it blows straight down the bays with minimal turbulence. Those bays actually seem to collimate the air, to some degree: The farther down the bay you get from the firing position, the straighter the wind blows.

Anything over 100 yards, however, is on the main firing line, fully exposed, and oriented such that the prevailing wind is always quartering and any change usually results in a full value crosswind (that's always variable). Shooting beyond 100 yards there, with any hope of precision, means doing so at the crack of dawn, or not at all.

[Unclenick]

Originally Posted by RC20

I had not a clue of all the calculations you could do with all that.

I will pass, I make myself nuts enough.

No need to go nuts. The Hornady 4 DOF program calculates the vertical drift that accompanies wind deflection for you.

[Stats Shooter]

There are 10 flags going out to the target in 100 yard intervals at the 1,000 yard range I shoot at. I have honestly been out there shooting with at least 1 flag showing winds out of each cardinal direction plus some 2 o'clock , 7 o'clock winds......all at the same exact time. Good luck shooting through that!

[RC20]

No need to go nuts. The Hornady 4 DOF program calculates the vertical drift that accompanies wind deflection for you.

Not that its not deeply interesting, but at some point ............


So, I get my wind profilers out on the range. Probably need one every 20 yards. So if I do shoot the 300 yard range.........

Then I run that into my Cray Super computer through the blue tooth, which is erratic (must be all that blast), that is in the back of the car, and have it crunch the average data to feed the 4 DOF.

After having taken all the fun out of it and shot up my wind profilers............

Kind of reminds me about that cool sight on the 1903 that adjusted for the right hand spiral that offset to the left or whatever.

By the time it makes any difference, you are dealing with wind and the wind is from where?

Yep, time to guess.

[Road_Clam]

The other wind issue with me where I like to test at 200 meters is my spotting scope. If the wind is vibrating your spotting scope the day's testing will be frustrating. I have a bungee "S" hook underneath my spotting scope tripod and I hang a 8# block of lead to add stability so I can verify my shots. Spotting .30 cal at 200 meters is not a problem but spotting .22 cal is a problem especially with wind vibrating my scope.

[NHSHOOTER]

We have been in a deep freeze up here in NH since xmas, minus 10 or more with windchill, No shooting for me. If it were warmer and the wind was a steady 15 cross I would still shoot @ 100 yds I dont think it would move the bullets off target at all unless I was shooting 22 rimfires which I dont..

[Unclenick]

Originally Posted by RC20

Kind of reminds me about that cool sight on the 1903 that adjusted for the right hand spiral that offset to the left or whatever.

Yeah, except wind is more variable. Spin drift is always in the same direction. It varies with atmospheric density and bullet gyroscopic stability factor, so that nifty, if delicate, '03 ladder sight is really set up for .30-06 150 grain ball ammo at near sea level. Fortunately, the foot or so of deflection it causes at 1000 yards is small enough that changing bullets won't move anyone off paper. It'll only be a couple or three inches of difference one way or the other in most instances.

[RC20]

We have been in a deep freeze up here in NH since xmas, minus 10 or more with windchill, No shooting for me. If it were warmer and the wind was a steady 15 cross I would still shoot @ 100 yds I dont think it would move the bullets off target at all unless I was shooting 22 rimfires which I dont..

We have been watching that. Pretty amazing to see Mid West and East Coast go well below our temperatures (under 10) wind off and on.

Our 100 yd range is close for December - days too short (Sun barely breaks the Horizon right now) to make it worth going to the 300 meter range (and cost)

If we go sub 0 the wind is usually non existent though that's less sure these days of non climate change.

We are good to -40 that I have seen a few times, its a bugger when you aren't set up for it. We are used to hurricane forced winds as well and seldom have issues with that. Our Hurricanes are not named as my wife likes to say. Usually with a warm spell, early spring or late summer.

Screwy is we have had little snow. What we had melted off and only got 6 inches of wet stuff after.

My neighbor got a new snow blower and is doing everyone driveway, I don't even have to shovel!

[Unclenick]

That's funny. I did the same thing the first year I owned a snow blower. Then the next year the guy next door got one and did the same while mine sat in the garage. There's just something about having an excuse to play with a new toy.

Snow here has been too little at a time to do anything but cover the lawn with a little white. The sidewalks and driveways are staying clear. That's about to end tonight, I gather, when more serious snow is supposed to move in.

[hounddawg]

well this has gotten way off topic but interesting as heck anyway.

All these cold stories make me feel guilty about not wanting to shoot when it is in low 40's. I drove south with a snow shovel attached to the front of my truck. When someone asked me what that funny shovel was for I drove another 200 miles south and declared it my new home.

Again this is just my range but the worst wind to shoot in is tail wind due to a skip berm for the first 250 yards with a open area on the far side. It acts like a funnel for tail winds into the mid and long range area. It creates a vortex effect at about 300 that I find impossible to read with any confidence

[Slamfire]

There are 10 flags going out to the target in 100 yard intervals at the 1,000 yard range I shoot at. I have honestly been out there shooting with at least 1 flag showing winds out of each cardinal direction plus some 2 o'clock , 7 o'clock winds......all at the same exact time. Good luck shooting through that!

So much for wind being predictable. Many times I have pointed out flags, same distance, on the left side and right side of the range, pointing at each other!