Any thing for a moa/moa scope? The mil wind estimation is great. All I have is moa. If there is a trick for moa, can you explain it in depth and give a couple of examples with math if there is any. Please and thank you.
Deano
Deano
- Thread starter Lowlight
- Start date
(Distance in yds X wind in mph)/constant
The hard part is the constant because it’s different for every caliber and sometimes there are multiple constants depending on range. Ryan cleckner gives examples here
D
Deleted member 113831
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A mil is 3.438 moa. So, a mil wind is a 3.438 moa wind right? So, you can use the first number of your G1 BC and know that, that is very close to a 3 moa wind for you using moa. Therefore, multiply the yard line by 0.3.
So, my "mil wind / 3 moa wind" is 6mph. At 700 yards, for a full value 6 mph wind, I multiply 0.3 x 7 to get a hold of 2.1 moa. Round to 2 moa.
This works very well. Just like with the mil wind, you can use your solver to find the precise wind that moves your bullet an even 3 moa at 1000 yards, and if you have a little more time you can be a little more exact.
But it really is just a matter of using the same wind and multiplying by 0.3 rather than 0.1.
The British method works for MOA scopes
The Long Hand formula in that video is bad, the constant is wrong that is the constant for a 168 / 308 only you have to fix it for higher BC bullets
If you are doing long hand math in the field or on the firing line you already lost, we stopped teaching that stuff a while ago
British formula
10MPH wind is your base wind. (wind speed that equals 1moa per 100 yd)
Off of base wind 2-3 = light 5 = medium 10 = base 20 = heavy
Example
Range 600, velocity 10mph = 6 moa
Range 600, velocity 5 mph = 3 moa
Range 600, velocity 2-3mph=1.5 moa
Range 600, velocity 20 mph = 12 moa (and call for indirect fire)
The Long Hand formula in that video is bad, the constant is wrong that is the constant for a 168 / 308 only you have to fix it for higher BC bullets
If you are doing long hand math in the field or on the firing line you already lost, we stopped teaching that stuff a while ago
British formula
10MPH wind is your base wind. (wind speed that equals 1moa per 100 yd)
Off of base wind 2-3 = light 5 = medium 10 = base 20 = heavy
Example
Range 600, velocity 10mph = 6 moa
Range 600, velocity 5 mph = 3 moa
Range 600, velocity 2-3mph=1.5 moa
Range 600, velocity 20 mph = 12 moa (and call for indirect fire)
D
Deleted member 113831
Guest
With something like a Creed, a 10mph wind moves the bullet 6moa instead of 10moa at 1000 yards, so that is why I do it the way mentioned above. The traditional, historical British method's fatal flaw is that it assumes a 10mph wind = 10moa at 1000 yards. Very few people are launching those types of bullets these days.
It fails because it sets or fixes both ends of the equation. Though, as has been discussed, the concept lends itself easily to modification. By only fixing as single side of it, the other side can be modified to fit actual drift. You can fix the wind to 10mph if you wish, then let the angle of deflection for that wind dictate the multiple you use for each yard line. If a 10mph wind moves the bullet 6moa at 1k yards, then your multiple is 0.6moa per 100 yards.
If you chose to fix the angle, say at 1 mil, or 3 moa or whatever, then the wind is what gets adjusted.
But as you've said many times before, it's "4", nobody owns "4" lot's of ways to do it.
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Interesting topic but my head is spinning a bit with all the back and forth. The BC method sounds very useful although I am an bit confused on how to figure it out for my specific rifle. I have a Rem 700 with 16.5 barrel with a 1/10 twist and use Fed GMM 175s that ave about 2400FPS. The box says my G1 BC is 0.496 and G7 0.243. Not sure where to go from from here.
Thanks skookum and low light. I appreciate you putting it in easy Terms.
Xdeano
Xdeano
The BC for the standard .308 is .4xx so you use a 4 mph window.
100 = .1 mil at 4 mph
200 = .2 mil
300 = .3 mil
400 = .4 mil
500 = .5 mil
600 = .7 mil due to velcity bleed off and correcting the estmate
700 = .8 mil
800 = .9 mil
900 = 1 mil
100 - 1.1 mil
Every four mph window then becomes a multiple so 16 mph wind at 500 is 4 times .5 mil or 2 mils.
This can be used for 5.56 with a BC of .3xx, using 3 mph windows, the 300 Win Mag with .5xx BC using 5 mph windows and so on. Adding .1 mil to the window for each mph, ie 5 mph at 500 is .6 mil will get you on the target.
This may be a stupid question but what is considered the standard i.e. is it different than the BC I listed above. BTW G1 or G7?
Cheers
I don’t know what the “standard” is per se. 168/175 gr probably but most .308 bullets fall in that .4xx BC realm (flatlines excluded). The BC method is based off G1. So you said a .496 g1 for your 175; so that’s a.4xx or you could even use 5 but 4 is better.
D
Deleted member 113831
Guest
At an elevation of 2000ft your base wind/mil wind is going to be a 3.5mph wind due to how slow it is starting to begin with. But using 4mph will work just fine for you to 800 yards which is where you go subsonic anyway.
D
Deleted member 113831
Guest
What you said is absolutely accurate, but it just doesn't have to be that complicated. Just know that the same bullet pushed 200fps faster than 2800fps gets another 1mph added to it's basic wind. If the bullet is 200fps slower than 2800fps it loses 1mph.
Yes. I didn’t add any any correction for the lower velocity due to the shorter barrel.
Delete
I am in the middle of some good old fashioned day drinking. I was going to wait until I had pictures of this idea being better-executed, but I am far too lazy to get a label maker right now. But I am going to give my best sales pitch for The Millennial Wind Thingy (Patent Pending Millenial MarksManship LLC)(IF YOU COPY THIS WE RESERVE THE RIGHT TO SUE THE FUCK OUT OF YOU.)
The Problem.
Have you ever woken up in the middle of the night in a cold sweat and think "Geez I fucking suck at math and reading wind. All of this math doesn't make any sense." Well good news for you...M-Cubed has completely re-invented how you can read and account for wind. It is so simple that basically every other method is completely obsolete. The old and busted method of wind reading is to think "I used x mils of wind at y distance for z caliber"...well no longer! Millennial MarksManship is changing the game by making shooters think simply "I used x miles per hour of wind" at any distance!
The old and busted way is to convert the miles per hour of wind that you see into a mathematical value expressed in mils or minutes of angle. Guess what? That is stupid because nobody can quickly think of how a .2 mil wind at 300 yards transfers to wind at 1000 yards. But guess no more because lazy piece of shit Millenials have figured out a better way.
The Wind Thingy
What is the wind thingy? It might look like a normal piece of masking tape with some random numbers put on it. In reality it is a high tech precision wind reading instrument that is going to automatically make you a better shooter.
How does it work you ask? We have taken our partners patented ballistic software to produce individualized data that is specific to your rifle and bullet combination. Our custom label give you how many miles per hour of wind it will take at that specific range to move your bullet 1/2 mil. Now instead of having to do complicated backwards math or just adding more wind and hoping it's right as you move to longer distances, you can create a specific reference.
This method is designed to work with our Target Reference Method as well. Our target reference method converts the target size into a wind width in miles per hour. This allows you to decide how much wind to use, and how precise your wind call will have to be.
Here is an example:
You are shooting at 2 MOA sized targets from 600 to 1000 yards. This is our data. The only thing that we have to do is turn our turret to the correct elevation and begin our wind call process.
600 Yard = 3.4 mils = 6 mph
700 Yard = 4.4 mils = 5.5 mph
800 Yard = 5.4 mils = 5 mph
900 Yard = 6.6 mils = 4 mph
1000 Yard = 8.0 mils = 3.5 mph
MWT tells us how many miles per hour of wind it is going to take to move our bullet .5 mil. And once you know that, it is easy to count by the MWT value to give a specific wind call. Before even shooting we still assign the wind a specific numerical value by observing the wind speed and value. And then we use the MWT to refine our wind call as we go along.
Let us assume that we assume a full value wind of 10 miles per hour as our initial wind call. We can look at our MWT and on our first target we know that 12 mph of wind is going to move the bullet 1 full mil.
We can also use the wind reference to know that our target is just under .75 mils wide, so it's width in wind would be our MWT value + 1/2 MWT Value. That works out to 6mph + 3mph = 12mph. Our target is 12mph of wind wide from edge to edge. As long as our wind call is within 12 miles per hour of the true value we should get a hit. Looking through the reticle it is even easier to visualize because at this distance 1/2 mil = 6 miles per hour.
Now we get to making the shot with our MWT. We have established the target is pretty big for wind. The easy way is to use 12 miles per hour of wind, and reduce it by a little bit...so we call it .8 mils. As long as we hit the target we can refine our wind value based on our Mil-scale.
We fire our shot. If it hits where we want it, we know that our wind call was true. If it even hits our short-range target, we can use the offset to correct the mile per hour value. If its off by roughly .25 mils, we know that the wind is +/- 3 miles per hour of our initial call.
And the process repeats itself as you walk out. And the MWT is FAST. However far away the strike of the bullet is from the center of the reticle can quickly be converted into an actual wind value.
Once we move all the way out to 1000 yard, we can see the advantages of the Millennial Wind Thingy. Although our target is still .75 mils wide, by using the MWT to convert the target width into a wind value, we can see that now our target is actually 5.25 miles per hour wide. That means even though our target is still the same size angularly...it is actually less than 50% of the size of our shortest range 600 yard target, and we know that this shot is now going to have a wind width of 5mph edge to edge. Now we know that we are going to have a much narrower margin of error than previously. We can also look at 5mph of width and realize that if the wind is any more than 5mph, if you hold one of the edges of the target...you will miss.
Let's say that we have an extreme case where there are only 2 targets. 1 at 600 yards and 1 at 1000 yards. They are both .75 mil targets. We shoot the 600 yard target holding 1.5 mils of wind. MWT tells us that is an 18 mile per hour wind. Now we crank our turret to 1000 yards. MWT tells us that 3.5 is our wind value; but we can use 3 or 4 mph if we just want to get close enough. But we have a lot of wind and want to be precise. We count by 3.5s until we get to 18mph...so .5mil=3.5, 1 mil = 7mph (and then we are like oh-shit whole numbers) 2 mil = 14mph, and 2.5 mil = 17.5mph...close enough.
CONCLUSION
Millenial Wind Thingy is a better way of doing business because it gives the discerning tactical marksman the ability to quickly visualize his existing milliradian reticle into easy to use wind-brackets, and use those as references to make faster and more precise wind calls. No longer will you have to come off the firing line thinking "I used x mils of wind" and instead start thinking in "I used x miles per hour of wind".
The Problem.
Have you ever woken up in the middle of the night in a cold sweat and think "Geez I fucking suck at math and reading wind. All of this math doesn't make any sense." Well good news for you...M-Cubed has completely re-invented how you can read and account for wind. It is so simple that basically every other method is completely obsolete. The old and busted method of wind reading is to think "I used x mils of wind at y distance for z caliber"...well no longer! Millennial MarksManship is changing the game by making shooters think simply "I used x miles per hour of wind" at any distance!
The old and busted way is to convert the miles per hour of wind that you see into a mathematical value expressed in mils or minutes of angle. Guess what? That is stupid because nobody can quickly think of how a .2 mil wind at 300 yards transfers to wind at 1000 yards. But guess no more because lazy piece of shit Millenials have figured out a better way.
The Wind Thingy
What is the wind thingy? It might look like a normal piece of masking tape with some random numbers put on it. In reality it is a high tech precision wind reading instrument that is going to automatically make you a better shooter.
How does it work you ask? We have taken our partners patented ballistic software to produce individualized data that is specific to your rifle and bullet combination. Our custom label give you how many miles per hour of wind it will take at that specific range to move your bullet 1/2 mil. Now instead of having to do complicated backwards math or just adding more wind and hoping it's right as you move to longer distances, you can create a specific reference.
This method is designed to work with our Target Reference Method as well. Our target reference method converts the target size into a wind width in miles per hour. This allows you to decide how much wind to use, and how precise your wind call will have to be.
Here is an example:
You are shooting at 2 MOA sized targets from 600 to 1000 yards. This is our data. The only thing that we have to do is turn our turret to the correct elevation and begin our wind call process.
600 Yard = 3.4 mils = 6 mph
700 Yard = 4.4 mils = 5.5 mph
800 Yard = 5.4 mils = 5 mph
900 Yard = 6.6 mils = 4 mph
1000 Yard = 8.0 mils = 3.5 mph
MWT tells us how many miles per hour of wind it is going to take to move our bullet .5 mil. And once you know that, it is easy to count by the MWT value to give a specific wind call. Before even shooting we still assign the wind a specific numerical value by observing the wind speed and value. And then we use the MWT to refine our wind call as we go along.
Let us assume that we assume a full value wind of 10 miles per hour as our initial wind call. We can look at our MWT and on our first target we know that 12 mph of wind is going to move the bullet 1 full mil.
We can also use the wind reference to know that our target is just under .75 mils wide, so it's width in wind would be our MWT value + 1/2 MWT Value. That works out to 6mph + 3mph = 12mph. Our target is 12mph of wind wide from edge to edge. As long as our wind call is within 12 miles per hour of the true value we should get a hit. Looking through the reticle it is even easier to visualize because at this distance 1/2 mil = 6 miles per hour.
Now we get to making the shot with our MWT. We have established the target is pretty big for wind. The easy way is to use 12 miles per hour of wind, and reduce it by a little bit...so we call it .8 mils. As long as we hit the target we can refine our wind value based on our Mil-scale.
We fire our shot. If it hits where we want it, we know that our wind call was true. If it even hits our short-range target, we can use the offset to correct the mile per hour value. If its off by roughly .25 mils, we know that the wind is +/- 3 miles per hour of our initial call.
And the process repeats itself as you walk out. And the MWT is FAST. However far away the strike of the bullet is from the center of the reticle can quickly be converted into an actual wind value.
Once we move all the way out to 1000 yard, we can see the advantages of the Millennial Wind Thingy. Although our target is still .75 mils wide, by using the MWT to convert the target width into a wind value, we can see that now our target is actually 5.25 miles per hour wide. That means even though our target is still the same size angularly...it is actually less than 50% of the size of our shortest range 600 yard target, and we know that this shot is now going to have a wind width of 5mph edge to edge. Now we know that we are going to have a much narrower margin of error than previously. We can also look at 5mph of width and realize that if the wind is any more than 5mph, if you hold one of the edges of the target...you will miss.
Let's say that we have an extreme case where there are only 2 targets. 1 at 600 yards and 1 at 1000 yards. They are both .75 mil targets. We shoot the 600 yard target holding 1.5 mils of wind. MWT tells us that is an 18 mile per hour wind. Now we crank our turret to 1000 yards. MWT tells us that 3.5 is our wind value; but we can use 3 or 4 mph if we just want to get close enough. But we have a lot of wind and want to be precise. We count by 3.5s until we get to 18mph...so .5mil=3.5, 1 mil = 7mph (and then we are like oh-shit whole numbers) 2 mil = 14mph, and 2.5 mil = 17.5mph...close enough.
CONCLUSION
Millenial Wind Thingy is a better way of doing business because it gives the discerning tactical marksman the ability to quickly visualize his existing milliradian reticle into easy to use wind-brackets, and use those as references to make faster and more precise wind calls. No longer will you have to come off the firing line thinking "I used x mils of wind" and instead start thinking in "I used x miles per hour of wind".
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I'm tracking on what you said, as well as what Skookum added to it a few posts down, but your last sentence here has me confused. Can you explain that for the math challenged, like me?
Now I'm tracking again, thanks! Missed the idea that you were jumping from 4mph to 5 mph.
SO with the lower velocity i.e. about -200 FPS since I think the box listed 2600 I would have to increase the mph due to the 175 only going about 2400. So maybe starting with a 5 mph window would be better?
If I'm understanding you correctly, then no, you should stick with 4mph. The lesser wind will affect your bullet more, since it is slower than normal. If you went to a 5 mph wind, you would be assuming a greater BC than your bullet will give you at its lower velocity.
If your MV is off, and please forget what the box says in terms of both MV and BC that is only valid under a certain set of conditions and has very little to do with what we are shooting.
BC are determined between 2800fps and 3000fps give or take, and they are averaged for 300 yards at that speed. If you look at the discussion regarding Sierra and Banding BC you can see where this falls and how they adjust the numbers
So if you take this information in to account you have to "TRUE" the BC for your MV and rifle system. What we are telling you is pretty simple and easy to follow, if you are pushing the bullet slower than advertised the BC will be lower, if you are pushing the bullet faster it goes up. That will help you determine the actual BC for your SYSTEM
Trying to overly old, bad information that has nothing to do with this is where you all fall down. Stop trying to put this in 1978 context it does not work, you have to look at the context we are describing which applies to modern shooting and Apps. If you actually take the time to true your velocity at say, 500 and your BC at 800 your stuff works better and instead of doing a big Trial and Error test and swing, we are attempting to explain how to take an educated crack at it
Go read MV and BC Truing
BC are determined between 2800fps and 3000fps give or take, and they are averaged for 300 yards at that speed. If you look at the discussion regarding Sierra and Banding BC you can see where this falls and how they adjust the numbers
So if you take this information in to account you have to "TRUE" the BC for your MV and rifle system. What we are telling you is pretty simple and easy to follow, if you are pushing the bullet slower than advertised the BC will be lower, if you are pushing the bullet faster it goes up. That will help you determine the actual BC for your SYSTEM
Trying to overly old, bad information that has nothing to do with this is where you all fall down. Stop trying to put this in 1978 context it does not work, you have to look at the context we are describing which applies to modern shooting and Apps. If you actually take the time to true your velocity at say, 500 and your BC at 800 your stuff works better and instead of doing a big Trial and Error test and swing, we are attempting to explain how to take an educated crack at it
Go read MV and BC Truing
D
Deleted member 113831
Guest
I shot in some pretty tricky wind yesterday. I thought I would break it down here. I am shooting a 308 with 175 grain Nosler Custom Competitions. BC is pretty much the same as a 175 SMK so, about a G7 .243 & G1 .500ish. I am shooting an old gas gun load of 39.5g of IMR4895 @ 2484fps. Slow, but extremely accurate and consistent.
The bullet based on the BC would be a "5", the initial assumption is that a 5mph wind would move it 1 mil at 1000 yards. Therfore, 0.1 mil per 100yds.
I'm only shooting it just under 2500 fps, so we change that assumption down to at least a "4", this is our "base wind".
The range is 753 yards
The wind is 3-6mph from North, switching to NW.
Firing direction is from North to South.
We take the actual wind, and divide it by our base wind. We do it once for the low and once for the high, these are our high and low correction factors.
3 / 4 = .75 correction factor, 6 / 4 = 1.5 correction factor
Our standard full value hold for our 4mph base wind at 753 yards would be .753 mils, it's the range expressed as a decimal (753 / 1000)
.753 mils x .75 correction factor = .56 mils (.6 rounded), This is our low side (3mph)
.753 mils x 1.5 correction factor = 1.12 mils (1.1 rounded), This our high side (6mph)
So this is our FULL VALUE wind bracket at this range.
Now for the tricky part. The wind was switching N to NW. So, it was coming right up my back then switching a bit to my right.
I'm on the side of a mountain, shooting across a small canyon that opens up a bit to my left, creating a small bowl that I'm shooting across the mouth of. When the wind is 3mph, and coming up my back, there is no cross wind to deal with. Center hold.
When the wind kicks up to 6 mph, the wind following the mountain wants to fill in the bowl to my left creating a crosswind right to left.
This cross wind is right at 22-25 degrees, so half value. Let's do the math:
6mph = 1.1 mils x .5 (half value) = .55 mils (.6)
When the wind switches to my right, the wind comes at about 45 degrees, so a .7 value.
3mph = .6 mils x .7 = .42 mils (.4)
6mph = 1.1 mils x .7 = .77 mils (.8)
When the wind was 6 mph and switching, the feeling was very distinct, the wind went from moving up my back, to down onto the top of my back. This is because a 6 mph wind has enough force to set up a light rotor on the edge of the cliff I was shooting from. This feels like being under a slight down draft from above.
The 3-4mph wind however, didn't have enough power to produce that rotor. When it switched, it just felt like the wind died because I was in the wind shadow of the cliff I was shooting from. So, not only did it give the impression of no wind, it actually increased in value by increasing it's angle to the bullet path. It took a few WTF!! shots to start looking for an answer to that one. The only way to tell the difference was by watching the leaves on the few deciduous trees between me and the target.
So, this is the wind I was dealing with for about 3 hours yesterday. I wish I could say I hammered the target every time, but it didn't happen. The wind changes were deceptively subtle, and the target I was shooting at was just larger than minute of angle. I shot 100 rounds in three hours, and I managed about a 40-50% hit rate, with most of the others being a tenth or two off the edge...a couple of handfuls I blew out of my ass and missed by a half mil or more. Shooter fatigue was definitely a factor toward the end.
So, hope this helps someone.
The bullet based on the BC would be a "5", the initial assumption is that a 5mph wind would move it 1 mil at 1000 yards. Therfore, 0.1 mil per 100yds.
I'm only shooting it just under 2500 fps, so we change that assumption down to at least a "4", this is our "base wind".
The range is 753 yards
The wind is 3-6mph from North, switching to NW.
Firing direction is from North to South.
We take the actual wind, and divide it by our base wind. We do it once for the low and once for the high, these are our high and low correction factors.
3 / 4 = .75 correction factor, 6 / 4 = 1.5 correction factor
Our standard full value hold for our 4mph base wind at 753 yards would be .753 mils, it's the range expressed as a decimal (753 / 1000)
.753 mils x .75 correction factor = .56 mils (.6 rounded), This is our low side (3mph)
.753 mils x 1.5 correction factor = 1.12 mils (1.1 rounded), This our high side (6mph)
So this is our FULL VALUE wind bracket at this range.
Now for the tricky part. The wind was switching N to NW. So, it was coming right up my back then switching a bit to my right.
I'm on the side of a mountain, shooting across a small canyon that opens up a bit to my left, creating a small bowl that I'm shooting across the mouth of. When the wind is 3mph, and coming up my back, there is no cross wind to deal with. Center hold.
When the wind kicks up to 6 mph, the wind following the mountain wants to fill in the bowl to my left creating a crosswind right to left.
This cross wind is right at 22-25 degrees, so half value. Let's do the math:
6mph = 1.1 mils x .5 (half value) = .55 mils (.6)
When the wind switches to my right, the wind comes at about 45 degrees, so a .7 value.
3mph = .6 mils x .7 = .42 mils (.4)
6mph = 1.1 mils x .7 = .77 mils (.8)
When the wind was 6 mph and switching, the feeling was very distinct, the wind went from moving up my back, to down onto the top of my back. This is because a 6 mph wind has enough force to set up a light rotor on the edge of the cliff I was shooting from. This feels like being under a slight down draft from above.
The 3-4mph wind however, didn't have enough power to produce that rotor. When it switched, it just felt like the wind died because I was in the wind shadow of the cliff I was shooting from. So, not only did it give the impression of no wind, it actually increased in value by increasing it's angle to the bullet path. It took a few WTF!! shots to start looking for an answer to that one. The only way to tell the difference was by watching the leaves on the few deciduous trees between me and the target.
So, this is the wind I was dealing with for about 3 hours yesterday. I wish I could say I hammered the target every time, but it didn't happen. The wind changes were deceptively subtle, and the target I was shooting at was just larger than minute of angle. I shot 100 rounds in three hours, and I managed about a 40-50% hit rate, with most of the others being a tenth or two off the edge...a couple of handfuls I blew out of my ass and missed by a half mil or more. Shooter fatigue was definitely a factor toward the end.
So, hope this helps someone.
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Firstly, as a newer shooter on the learning curve toward understanding the wind, I greatly appreciate the time you took to lay out the practical application of applying the bullet BC value and wind brackets.
Now I have some homework to do and apply these concepts to my 6.5 CM.
I just want to say I finally fucking got it. I just listened again to mike and franks pod casts and with some more reading if skookums posts and it just clicked and I can do it in my head. Talk about a slow learner but how good is this bc method genius stuff man thanks heaps
So...I took a variation on the info put out by Mike/Frank and added a touch from a video I saw on YouTube and here's what I've come up with.
1. Start with the same 5mph, 90 degrees, and plug that in to your ballistic software.
2. You'll get whatever the wind data is. For my 6.5CM there were a lot of flat spots in the wind deflection, so in step 2, adjust the wind speed until you get a linear progression. Meaning: Increase wind until 100 = 0.1, 200 = 0.2, 300 = 0.3, and so on. For my 6.5CM shooting Prime ammo, it was at 7mph. It was "linear," until 1000, where it was 1.1. This makes it VERY easy to memorize.
3. So...after step 2, you have your base wind value. In my case it's a 7.
So...how do you "calculate," holds on the fly?
Ex # 1: 10mph full value wind at 600 yards
1. Take 10/7 = 1, with 3 left over.
2. 1 x wind dope at 600 = 0.6 = 0.6mil
3. Add the "left over," from Step 1. 3 = 0.3mil
4. So...total wind hold = 0.9 for a 10mph full value wind at 600 yards
Ex # 2: 5mph full value wind at 900 yards
1. 5/7 = 0.8, no left over
2. 0.8 x 0.9 = "72" = 0.72
3. No left over
4. Total wind = 0.7mil for a 5mph full value wind at 900 yards
Ex # 3: 20mph full value wind at 400 yards
1. 20/7 = 2, with 6 left over
2. 2 x 0.4 = 0.8
3. Left over = 6 = 0.6. 0.8 + 0.6 = 1.4
4. Total wind = 1.4mil for a 20mph full value wind at 400 yards
********************
This matches really well, it's easy to setup and memorize. My 6CM for example has a base wind of 8mph.
I haven't had a chance to take it to the range and see how it works out on steel, but it's lining up with the software and is easy to remember. Hope it helps.
1. Start with the same 5mph, 90 degrees, and plug that in to your ballistic software.
2. You'll get whatever the wind data is. For my 6.5CM there were a lot of flat spots in the wind deflection, so in step 2, adjust the wind speed until you get a linear progression. Meaning: Increase wind until 100 = 0.1, 200 = 0.2, 300 = 0.3, and so on. For my 6.5CM shooting Prime ammo, it was at 7mph. It was "linear," until 1000, where it was 1.1. This makes it VERY easy to memorize.
3. So...after step 2, you have your base wind value. In my case it's a 7.
So...how do you "calculate," holds on the fly?
Ex # 1: 10mph full value wind at 600 yards
1. Take 10/7 = 1, with 3 left over.
2. 1 x wind dope at 600 = 0.6 = 0.6mil
3. Add the "left over," from Step 1. 3 = 0.3mil
4. So...total wind hold = 0.9 for a 10mph full value wind at 600 yards
Ex # 2: 5mph full value wind at 900 yards
1. 5/7 = 0.8, no left over
2. 0.8 x 0.9 = "72" = 0.72
3. No left over
4. Total wind = 0.7mil for a 5mph full value wind at 900 yards
Ex # 3: 20mph full value wind at 400 yards
1. 20/7 = 2, with 6 left over
2. 2 x 0.4 = 0.8
3. Left over = 6 = 0.6. 0.8 + 0.6 = 1.4
4. Total wind = 1.4mil for a 20mph full value wind at 400 yards
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This matches really well, it's easy to setup and memorize. My 6CM for example has a base wind of 8mph.
I haven't had a chance to take it to the range and see how it works out on steel, but it's lining up with the software and is easy to remember. Hope it helps.
D
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This is essentially the same math that I did above, but the way you handle the "left over" and add it to the rest is something I haven't seen before.
I'm stealing that shit, just so you know.
I just came on shift and didn't have time to read through the thread. Sorry for hijacking the method if it's similar. Like I said, it's a hybrid of a couple of different methods that I've found other than the base wind value, which sounds like what you do. I'm still really new to LR shooting, but am a bit of a math geek. So, hopefully this works out.
Appreciate the 'stealing that shit,' as I'll take it as a compliment.
D
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I've been playing with this some more. I have been using ranges from 400 yards to 1000 yards and using base winds of 4 mph, 5mph and 7 mph to represent the 308 Win and 6.5 Creed class of cartridges.I just came on shift and didn't have time to read through the thread. Sorry for hijacking the method if it's similar. Like I said, it's a hybrid of a couple of different methods that I've found other than the base wind value, which sounds like what you do. I'm still really new to LR shooting, but am a bit of a math geek. So, hopefully this works out.
Appreciate the 'stealing that shit,' as I'll take it as a compliment.
With the 308's, you will be within a tenth or two at medium ranges, and you could be as much as 3 tenths off at 1000 yards. But I used extreme cases to find out what the maximum would be. I used winds that were doubles and triples of the base wind minus 1mph.
The 7mph class rounds did extremely well, even using triple the base wind, minus 1mph. These were more accurate at the longer ranges, and could be up to 3 tenths off at 400 yards. Of course, at 400 yards that is only 4 inches or so. So it isn't nearly as critical.
In the extreme cases, it would be better just to go ahead and figure that extra 1mph in or out, making it an even double or triple wind value and add or subtract a tenth. But over all, a really neat cheater, thanks for showing it.
I got my 308 to work with a 4.8 mile an hour wind. 175 grain SMK at 2710, but it’s definitely not as clean
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Been traveling and been busy with a remodel but want to say that the information posted above by TacticalDillhole & Skookum was put to the test in my first match last month and i did a whole lot better than I thought i.e. i was not in last place.
I did have trouble reading the windsocks (different speeds and slightly different directions) and the mirage while trying to focus on the fundamentals. I also had to deal with some feeding issues with a new mag... but I had a great time and met some good folks.
My second match and a more challenging COF is this weekend so I am going to take Lowlight's advice and look for the thread on "Sierra and Banding BC" and true up my baseline numbers.
I did have trouble reading the windsocks (different speeds and slightly different directions) and the mirage while trying to focus on the fundamentals. I also had to deal with some feeding issues with a new mag... but I had a great time and met some good folks.
My second match and a more challenging COF is this weekend so I am going to take Lowlight's advice and look for the thread on "Sierra and Banding BC" and true up my baseline numbers.
I understand this method is a tool the shooter can use to get close in the field, and is not exact.
Is there any similar rule of thumb for accounting for spin drift? Or are you guys just adding a click or subtracting a click based on wind direction? Curious how (or if) you deal with it when shooting without referencing a ballistic app. Thanks.
Is there any similar rule of thumb for accounting for spin drift? Or are you guys just adding a click or subtracting a click based on wind direction? Curious how (or if) you deal with it when shooting without referencing a ballistic app. Thanks.
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What I have personally been doing is this...rounds that are traditionally stabilized at 30 - 32 calibers per turn, I use 2% of drop. For rounds that are stabilized at 28 calibers per turn or faster, I use 1% of drop. I'm still playing with it, but it seems to be working pretty well.
Well, that method definitely agrees closely with Hornady 4DOF's predictions for my 6XC. Mine is an 8 twist, so about 33 calibers, but 2% seems to work well. And the mental math is easy, just take 1% and double it. Thanks for the tip!
In the spirit of answering the original question of "How do you dope the wind?", here is what I was doing before learning the BC method.
On my dope card that I would tape to the rifle, for each range next to the moa of drop, I would write the drift for 1mph of wind. Then in the field I would estimate the wind in mph, and multiply my 1mph wind drift by that estimate. So if drift at 400 yards at 1mph is 0.21 moa, and my actual wind is 4 mph, I would hold 0.84 moa into the wind (0.21 x 4 = 0.84). Simple.
Of course a ton of people do this, but most people I've talked to write the 5 or 10mph drifts on their dope card. To me, multiplying drift by the 4mph observed wind was easier than dividing 4 mph by 10mph and multiplying by the 10mph drift to get the same answer.
If only worrying about your own wind adjustments, (not calling wind for multiple other shooters) is there a downside to doing it that way?
On my dope card that I would tape to the rifle, for each range next to the moa of drop, I would write the drift for 1mph of wind. Then in the field I would estimate the wind in mph, and multiply my 1mph wind drift by that estimate. So if drift at 400 yards at 1mph is 0.21 moa, and my actual wind is 4 mph, I would hold 0.84 moa into the wind (0.21 x 4 = 0.84). Simple.
Of course a ton of people do this, but most people I've talked to write the 5 or 10mph drifts on their dope card. To me, multiplying drift by the 4mph observed wind was easier than dividing 4 mph by 10mph and multiplying by the 10mph drift to get the same answer.
If only worrying about your own wind adjustments, (not calling wind for multiple other shooters) is there a downside to doing it that way?
D
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Lots of good ways to do it. If you are getting hits, then you are correct.
Just reporting back in on the results... I scored 11 points higher than my first match. I know it does not sound like much but the COF was harder so I am on the right trajectory! Thanks all!
I want to mention that lots of folks were surprised I was shooting a 16.5 in barrel. The general consensus is "get a new (longer) barrel" & "upgrade you Hunter 700 stock". Most guys I talked to would agree the short barrel 308 in a Hunter 700 stock is a handicap esp as the wind picks up and the range goes 800+
I would like to go chassis for flexibility... way to many options! I have looked at the XLR and the KRG Whiskey 3 but I have a possibility to get a slightly used J Allen which is the JAE 700 I think.
Cheers!
I want to mention that lots of folks were surprised I was shooting a 16.5 in barrel. The general consensus is "get a new (longer) barrel" & "upgrade you Hunter 700 stock". Most guys I talked to would agree the short barrel 308 in a Hunter 700 stock is a handicap esp as the wind picks up and the range goes 800+
I would like to go chassis for flexibility... way to many options! I have looked at the XLR and the KRG Whiskey 3 but I have a possibility to get a slightly used J Allen which is the JAE 700 I think.
Cheers!
I knew I would get one of you to follow the true method of wind calling, hahahahahaha
The Gunwerks Questions are good,
If you have to break out a calculator you already lost, plus the Constant he is using is from the old USMC Formula, however that Constant is for a 168gr 308, vs a 6.5, now depending on the size of the target etc, it will work. Based on the caliber and video he hit but on the left so he held too much by a touch. Not knowing target size we can't figure out if .4 or .3 would be better?
There are easier rules of thumb as well like the British Method for quick in your head stuff.
British Method
10MPH wind is your base wind.
1 MOA @ every 100 yards
Wind MPH 2-3 MPH = light, 5MPH = medium
10MPH = base, 20MPH = heavy
Example
Range 600, velocity 10mph = 6 MOA
Range 600, velocity 5 mph = 3 MOA
Range 600, velocity 2-3mph=1.5 MOA
Range 600, velocity 20 mph = 12 MOA
But the video was simple and worked. If you actually run the formula backward to fix the constant. you get,
.4 Wind (bring him back into the center a bit)
35 / 1.4 (MOA conversion)
25 for a constant which fixes the problem.
It's a good simple video, he explains it fine, but he missed the fact the constants are bullet specific.
If you have to break out a calculator you already lost, plus the Constant he is using is from the old USMC Formula, however that Constant is for a 168gr 308, vs a 6.5, now depending on the size of the target etc, it will work. Based on the caliber and video he hit but on the left so he held too much by a touch. Not knowing target size we can't figure out if .4 or .3 would be better?
There are easier rules of thumb as well like the British Method for quick in your head stuff.
British Method
10MPH wind is your base wind.
1 MOA @ every 100 yards
Wind MPH 2-3 MPH = light, 5MPH = medium
10MPH = base, 20MPH = heavy
Example
Range 600, velocity 10mph = 6 MOA
Range 600, velocity 5 mph = 3 MOA
Range 600, velocity 2-3mph=1.5 MOA
Range 600, velocity 20 mph = 12 MOA
But the video was simple and worked. If you actually run the formula backward to fix the constant. you get,
.4 Wind (bring him back into the center a bit)
35 / 1.4 (MOA conversion)
25 for a constant which fixes the problem.
It's a good simple video, he explains it fine, but he missed the fact the constants are bullet specific.
Yes he did. wasnt clear on that.
D
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Much simpler to say," My bullet is a 6, and the wind is a 6, so the hold would be 0.5 mil, but that angle makes it 0.4 mil......bang.....ding"
In one of the other podcasts Adam talked about having a "wind budget" for a certain size target at a certain range and using the budget he could better his chances of a hit in the wind. Anybody able to expound on this?
We talk about it a lot and it's in the YT videos from the class
A wind budget is simply looking at the size of the target and where the Wind High and Low fall within that target size.
So you need know how big the target is, then how much your bullet will move vs the High and Low Gusts
A wind budget is simply looking at the size of the target and where the Wind High and Low fall within that target size.
So you need know how big the target is, then how much your bullet will move vs the High and Low Gusts
I have a long way to go. Just when i think I’m getting it, I’m confused again. ??
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I'm sorry if I confused you, the post you quoted from me is a bit cryptic. The video is of a gentleman using the Army method which as you see, requires a bit more math process and a known constant to arrive at the hold.
My comment was a bit of mental shorthand, contrasting it to my thought process using the BC method on the same problem.
D
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I can't get into that link.
Sorry, just a mock book cover...Down & Dirty Wind Reading For Dummies.
Apparently, I need “Posting on Forums for Dummies” as well ?
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