Range Report Accuracy first wind formula

[GhengisAhn175]

Question if anyone knew the factoring # for a 260 Remington.

I know 308 is 4 (every 4mph wind) and 300wm is 5.. Unknown for the 260?

Any way to calculate this out for any caliber? Maybe i missed that in AOTPR

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[Graham]

Accuracy first wind formula

Google "British Wind Formula".

It's also in Mike Lau's book, circa the 1990's.

Variations on a theme, with a different kind of constant.

 

[bigbear_98]

If you get on your ballistic calculator and push the wind speeds around until the numbers match what is on their chart you will come to it. One of the guys in the class I took was shooting a 6.5 Creedmore and From what I remember it was like 6-7 mph intervals. My Grendel was 5mph.

 

[Lowlight]

You use the first number of the BC to determine,

BC Based Method

The BC method simply states that 308 has the BC of .4 so you use 4 MPH. If you use a bullet with a different BC that first number is the value you use for the wind speed. So a 5.56 would use 3 MPH based off the .3 BC for the bullet.

100 = .1 mil @ 4 mph
200 = .2 mil
300 = .3 mil
400 = .4 mil
500 = .5 mil

After 500 yards the velocity is changing you so have to adjust the values to account for this. It jumps up by .1 mils here.
The numbers continue this way.

600 = .7 mil
700 = .8 mil
800 = .9 mil
900 = 1 mil
100 - 1.1 mil

Pretty simple you just change the MPH value for .1 mils based off the bullet’s BC. It’s not perfect, but it’s fast and easier to remember than doing a long hand math formula in the field.

There are others, it's not really, "their" formula it's just another way to do the math.

The British Method is 10MPH, the Rules of 9s, is 9...

The Rule of Nines

Similar to the British Method, you simply take the wind speed and multiply it by the range in 100 meter increments and then using the base value, 9 = .25 Mils, 18 = 5. Mils, and 36 = 1 Mil, you have the following example.
7 MPH @ 500m = 35, here 35 is close to 36 so you would use a light 1 Mil for the hold. Its not perfect but close enough for government work. If you had a 3 MPH wind at the same range the answer would be 3 x 5 = 15 which is close to 18 so a light .5 mils hold. Is this not 1/4 minute perfect, but it will solve a minute of man problem in the field.

 

[GhengisAhn175]

hot damn, an answer from the man himself! Thank you for the info gentlemen that helps quite a bit!

 

[GeKados]

[MENTION=7]Lowlight[/MENTION] thanks for those information.

If I am not wrong, in the "MD Precision Rifle" CD2 , Todd said that we must add 0,1 MIL starting with 700m so we will have 0,8 MIL at that distance for 4mph wind.
I know that is very small differece but from your experience wich formula is closer to the truth?

Thanks

Best

 

[Lowlight]

I don't remember the video, I try to forget what's not relevant but I believe he was talking about a 300WM, my example is a different caliber. Do you think that 700 yard slide works for a 5.56. And 700 does say .8...

Honestly the formula is not right, it's a rule of thumb, minute of man solution. If you want right run the numbers for your system and develop the solution for your rifle and bullet combination.

Anytime you have "slide" the values you're doing it half assed. Nothing about it says precision rifle, it's a battle rifle formula.

 

[Graham]

Accuracy first wind formula

Nothing beats experience shooting in the wind. Experience shooting on the same terrain in the same wind is even better.

Despite what Acc 1st teaches or advertises about what it teaches, if you have time to set up the shot you don't guess by using a formula that you know isn't accurate; and when the air-lead density is high no one is doing mental wind calculations anyway.

It is, however, fun to try on the range or in a PR class.

...And it's also Operator as Fuck.

 

[GeKados]

[MENTION=7]Lowlight[/MENTION] he speaks about 308 in that video but no matter. Although, all that you say is right...is a rule of thumb and not precise formula.
[MENTION=13650]Graham[/MENTION] I have some problems shooting in the wind at long range because I don't have where to shoot in my area more then 200m.
So I drive a lot of km just to shoot at 700-1000m and there I find my lack of experience for shooting in the wind, most of my problems are lack of reading wind changes.. I have the same opinion like you: nothing beats the experience .
Anyway , what I've seen on that video about wind lesson I've belived because it was simple and seemed legit (no big differences between data from JBM and this rule of thumb) and I just memorised it.

Thanks to both of you

Best

 

[Lowlight]

If you consider with a moving target after 500 you have to change the lead, the same would hold true with wind.

Plus with them advocating odd twists and low velocities that focus on transonic transitions, I guarantee none of that rules works for that combination.

It's smarter to dope your actual load than to use something that doesn't tell you MV, TOF, etc. It takes no extra effort to do it right for your load prior to leaving the house and printing a wind chart for your rifle.

No math, no formulas, not bullshit rules of thumb that don't apply, just true data at your finger tips. Learn that and you can ignore half ass solutions.

On the military side if 10 guys from a unit averaged their MV you could create a chart with JBM that is free and will be closer than using a sliding scale. Then you have relevant useful data. Hell you can do just a wind chart for each rifle and include it. Minimal effort to do it correctly. Why people embrace shortcuts in 2014 when access to software is widespread and free.

 

[GhengisAhn175]

Thanks a bunch you guys

Luckily the post here offers a 1km range and I've been practicing but would like to make my bullets count since they cost an arm and a leg

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[GhostFace]

Okay, I'm late to the discussion and I may not be tracking. But are you saying the "slide" (Whizwheel) with your actual muzzle velocity using their wind formula on thw wheel isn't accurate? Like I said I apologize if I'm not following you guys...

 

[Lowlight]

You're not tracking...

 

[GhostFace]

LOL...figures...


it just threw me off when you guys were talking about slide and then threw in Accuracy 1st. Let me get a cup of Joe and reread this thread...

 

[GeKados]

If you consider with a moving target after 500 you have to change the lead, the same would hold true with wind.

Plus with them advocating odd twists and low velocities that focus on transonic transitions, I guarantee none of that rules works for that combination.

It's smarter to dope your actual load than to use something that doesn't tell you MV, TOF, etc. It takes no extra effort to do it right for your load prior to leaving the house and printing a wind chart for your rifle.

No math, no formulas, not bullshit rules of thumb that don't apply, just true data at your finger tips. Learn that and you can ignore half ass solutions.

On the military side if 10 guys from a unit averaged their MV you could create a chart with JBM that is free and will be closer than using a sliding scale. Then you have relevant useful data. Hell you can do just a wind chart for each rifle and include it. Minimal effort to do it correctly. Why people embrace shortcuts in 2014 when access to software is widespread and free.

I understand your point of view and it make sense!
To calculate the firing solution I use JBM Ballistic and Streelok with the MV averaged (I don't have the posibility to measure always the MV) and everytime when I shoot over 500m I write all the data (fire solution, correction and atmospheric conditions) in the my data book ... so I have some true informations to make a real wind chart for my rifle.

For the future , I will put more attention in this data that I have from the range and....from my side, to learn better reading the wind changes.

 

[Lowlight]

I would practice just doping it once and holding center and not chasing the wind...

I shot today in some pretty good gusting winds and even with a 16" KAC EMC, the groups were sub MOA, there was no horizontal stringing taking place and technically, wind wise you had about .25 mils to .5 mils of what should have been a difference. Instead I held my adjustment for the entire string and it grouped perfectly.

Sure with the F Class crowd you see a lot of changes, but they are trying to stay within the "X" ring, but once that initial call is made they are only bouncing between center and maybe the 10 rings, or the outside edge of the "X"...it's minimal. I think this a very common misconception to "Chase" the wind and move too much, instead of doping it and holding strong based off that call. If you keep trying to "re-dope" every shot, you add a lot into the mix that is unnecessary and that probably causes more problems then is solves. A little goes a long way, and that idea is more or less about grouping and not about getting the round on target.

Make the call, get the hit and then hold it, focus on the fundamentals... have a plan, have a wind card, and stick to the plan, don't chase it. If all else fails, believe the bullet. It will give you 100% of the data you need to make that hit off the very first shot, even if you held no wind. The bullet doesn't lie unless you give bad information based on your fundamentals of marksmanship. If the call doesn't work, it is very likely because you are not doing your part.

 

[Deleted member 10043]

Nothing beats experience shooting in the wind. Experience shooting on the same terrain in the same wind is even better.

I second Graham's motion and will show an example of the type of range that is good for windage challenge.

Attached is a view of Range #5 at the Roswell Gun Club. This is an awesome range for windage practice. There are additonal berms on the 1000 yard range to the left, including a massive berm behind the the 1000 yard line and additional berms on ranges to the right. What works @200 meters will not work at 300 and so forth. There are a lot of variables at work here including crosswinds in all directions down range. Friday was mild variable 5 mph 9:00 for the 500 meter line. That day the correction [MENTION=80736]500[/MENTION] meters was L0.5 mils. Saturday morning it was mild variable 13 mph @11:30. The correction was the same. It won't be the same again at this range unless you have photographic memory that goes back years. At this range with anything above 10 mph wind that is not directly behind you or in front of you is challenging. It sounds easy but it is not. This is a very frustrating range. Thus, it is good for practice with windage. And it is almost always windy. Plenty of wind to keep you occupied and prevent you from going home a happy camper. But this type of practice makes you better with windage. Notice that shooting 200 meters will have a different wind direction than shooting at the other known distances. Some sick fuck thought how to make it more frustrating by staggering the direction of the berms from the firing line.

BTW, I believe this is called a chicken silhouette range. The old ranchers don't call the distance. They call 500, Rams. 385, Turkeys. 300, Pigs. And 200, Chickens. Competition on this range no longer includes these animal shapes and sizes. To make it more challenging for 6 BR shooters the steel targets represent 2 MOA at that particular distance. But it creates the need for even better accuracy and skill on the part for someone shooting .308 and so forth.

 

[dariof]

You use the first number of the BC to determine,

BC Based Method

The BC method simply states that 308 has the BC of .4 so you use 4 MPH. If you use a bullet with a different BC that first number is the value you use for the wind speed. So a 5.56 would use 3 MPH based off the .3 BC for the bullet.

100 = .1 mil @ 4 mph
200 = .2 mil
300 = .3 mil
400 = .4 mil
500 = .5 mil

After 500 yards the velocity is changing you so have to adjust the values to account for this. It jumps up by .1 mils here.
The numbers continue this way.

600 = .7 mil
700 = .8 mil
800 = .9 mil
900 = 1 mil
100 - 1.1 mil

Pretty simple you just change the MPH value for .1 mils based off the bullet’s BC. It’s not perfect, but it’s fast and easier to remember than doing a long hand math formula in the field.

There are others, it's not really, "their" formula it's just another way to do the math.

The British Method is 10MPH, the Rules of 9s, is 9...

The Rule of Nines

Similar to the British Method, you simply take the wind speed and multiply it by the range in 100 meter increments and then using the base value, 9 = .25 Mils, 18 = 5. Mils, and 36 = 1 Mil, you have the following example.
7 MPH @ 500m = 35, here 35 is close to 36 so you would use a light 1 Mil for the hold. Its not perfect but close enough for government work. If you had a 3 MPH wind at the same range the answer would be 3 x 5 = 15 which is close to 18 so a light .5 mils hold. Is this not 1/4 minute perfect, but it will solve a minute of man problem in the field.

Lowlight,

Quick clarification please. In the chart you posted, if the wind were at 8 mph, would the chart read:

100 = .2 mil @ 8 mph
200 = .4 mil
300 = .6 mil
400 = .8 mil
500 = 1.0 mil

 

[NachtKracht]

[MENTION=101218]dariof[/MENTION]
Yes, your correct.
And if the wind comes from 1,5,7, 11 oclock you divide the answer by 2.
Example;
You shoot a bullit with a bc of .325, than the list would be the same but with a wind falue of 3 mph,
So 100 again .1
200 .2
Etc
Etc
500 .5

If the wind is 6mph then multiply the above numbers by 2
So 100 will be .2
200 .4
Etc etc
500 1.0
But is the wind coming from 1' oclock, then divide by 2 which would result again in
100 .1
200 .2 etc

Is the wind not 3 but 9mph coming from 9 or 3 oclock, just triple the list
So 100 .3
200 .6
300 .9
Etc

Kind regards,

NK

 

[jdr724]

TAG

 

[madpat]

Is this formula including spin drift or should I + or - sd from value? Somebody use it for 338 LM? I tried but result are bad.

update: I think it doesn't include spin drift..

 

[Deleted member 113831]

Is this formula including spin drift or should I + or - from value? Somebody use it for 338 LM? I tried but result are bad.

This thread is from 2014.

No it doesn't include spin drift. Figure spin drift at 1% of drop and you will be really close.

Use a ballistic calculator to find the wind that gives you and average of 0.1Mil drift per 100 yards. That is the MPH for your gun.

A 338 LM shooting either 250's or 300's match bullets at 2700+fps should be either a 7mph or 8mph gun.

 

[Steel head]

Is this formula including spin drift or should I + or - sd from value? Somebody use it for 338 LM? I tried but result are bad.

update: I think it doesn't include spin drift..

Don’t forget Coriolis!!!!

 

[madpat]

I know about date of this topic but I won't double it I use 300gr bullet - LAPUA GB528

@Steel head I'll try thanks

 

[A&8's]

This thread is from 2014.

No it doesn't include spin drift. Figure spin drift at 1% of drop and you will be really close.

Use a ballistic calculator to find the wind that gives you and average of 0.1Mil drift per 100 yards. That is the MPH for your gun.

A 338 LM shooting either 250's or 300's match bullets at 2700+fps should be either a 7mph or 8mph gun.

Don't you want to turn off spin and coriolis in your calc, too.

To cancel the calc's spin drift, you can set your twist rate to 1:0, also. If I'm not mistaken.

 

[Deleted member 113831]

Don't you want to turn off spin and coriolis in your calc, too.

To cancel the calc's spin drift, you can set your twist rate to 1:0, also. If I'm not mistaken.

Yes, Turn those off. I forgot to mention that.

I'm not sure what you mean about the twist rate. Never had to do anything like that.

Thanks.

 

[Deleted member 113831]

I know about date of this topic but I won't double it I use 300gr bullet - LAPUA GB528

@Steel head I'll try thanks

I just meant that there are much more recent threads where the MPH method is explained in much more detail.

Given Lowlights responses in the old part of this thread, he wasn't too keen on it then, but with better data it has since become central to his current wind method.

 

[A&8's]

Yes, Turn those off. I forgot to mention that.

I'm not sure what you mean about the twist rate. Never had to do anything like that.

Thanks.

I have set my twist rate to 0 in BallisticARC, when I figure what mph my gun is. It seems to work perfect. I got the idea from another hide member while talking about 22LR wind stuff.

 

[Deleted member 113831]

I have set my twist rate to 0 in BallisticARC, when I figure what mph my gun is. It seems to work perfect. I got the idea from another hide member while talking about 22LR wind stuff.

I see, I have BA as well but don't use it much. I didn't even realize that SD couldn't be turned off.

Strelok Pro and AB are my most used apps.

 

[madpat]

I have read about britsh metod etc. I know this metod base on BC but not this ammo..
I use this topic because it was the most recent of those I found and a clue with 0.1 mil wind will help me

 

[A&8's]

I see, I have BA as well but don't use it much. I didn't even realize that SD couldn't be turned off.

Strelok Pro and AB are my most used apps.

I mainly use BA for 22 stuff. I host NRL22 style matches and I upload the stages in the range card section for other BA users.

For the past 4-ish months, I have used just hard data for my CF rifles. I used a calc to get hard data for different DA's, after I gathered hard data initially. I made up pocket cards for a couple different DA's. I check the DA in the morning and write my data down for each yard line and call it good. If the temp changes a lot, I'll check the pocket cards, but even then, I'm only looking at .1 difference. It has made my life so much easier not staring at my phone. It also seemed to help me remembering data.

 

[Deleted member 113831]

I have read about britsh metod etc. I know this metod base on BC but not this ammo..
I use this topic because it was the most recent of those I found and a clue with 0.1 mil wind will help me

The british method was for moa, and wasn't all that accurate past 600 yds anyway. It goes all the way back to when 303 British with a 170ish bullet at 2450fps was the norm.

The British method set BOTH the angle of deflection (10 moa at 1k yards), AND the wind speed (10 mph).

The MPH method is an adaption of the BC method. The BC method used the first number of the G1 BC to indicate the wind that would give 0.1mil per 100 yards drift.

It was better because it set the angle (1 mil at 1000 yards), but left the wind speed variable. There is a close correlation between that first G1 number and drift at speeds around 2,800 fps, but the BC method did not account for rounds at considerably different speeds, or altitude changes.

The MPH method sets the angle, but lets the actual round tell you what MPH of gun it is. The MPH method also recognizes that the number changes depending on elevation.

If your gun is a 6mph gun at sea level, it will be a 7mph gun at 4,000ft ASL. 4,000ft = 1mph change.

 

[Steel head]

I know about date of this topic but I won't double it I use 300gr bullet - LAPUA GB528

@Steel head I'll try thanks

I was being an ass with that post.
I pretty much ignore spin drift and Coriolis.