Rifle Scopes MOA Wind Math

[Lowlight]

Okay, rather than chase the details in that Mil vs MOA thread I am starting a new one with the math being discussed for using a single MPH with MOA like we do with Mils.

History,

We are a Base Wind / MPH which translates very well in Mils to our wind doping. There are multiple threads on the subject, but in simple terms:

First Number of the G1 BC gives the shooter his base wind for that bullet being used in MPH.

6.5 G1 BC of .545 would equal at 5MPH Gun. That translates to:

200 = .2
300 = .3
400 = .4
500 = .5
600 = .6 Mils

This for 5 MPH wind, a 10 MPH would be double the value, so 500 yards @ 10 MPH = 1 Mil Wind Hold

The MOA solutions are not so simple, and we have several variations on the methods. The British Method, the USMC Method, and the use of Constants which can vary from Caliber to Caliber. In the interest of creating an easier solution that does not require longhand math a bunch of guys have put their heads together to simplify the process for guys shooting scopes based in MOA.

While we have different methods to address the same subject, it's about teaching new shooters to understand the methods and not have to break out calculators in the field. Many guys will default to simple charts carried and this works great. It means you only do the math once and then you read the results as necessary. But still we wanted a method that works the same as Mils.

Fractions vs Base 10 is the issue and why we have a daily debate, Mils vs MOA for long range shooting.

One of the answers we have hit on, thanks to a couple members, including @C_R_Slacker was to use the MPH method were the wind equals 1 MOA @ 500 as your base wind. For our example using a modern caliber (VS the old 168gr 30-8 stuff that is everywhere for MOA shooters) was to translate the Mil Data to MOA. This cuts the wind in 1/2 but lines the data up in a logical order.

3 MPH Wind for my 6.5 143 Data:

100 = .2
200 = .4
300 = .6
400 = .8
500 = 1.0
600 = 1.25
700 = 1.5
800 = 1.75
900 = 2.0
1000 = 2.5
1100 = 2.75

This becomes your base hold which is adjusted for your system and caliber, after that it is just a cosine or addition. Same as using Mils. We want to round the values to actual adjustments so you might see .3 MOA rounded to .25 and .4 rounded to .5 MOA because that is how our scopes adjust. We have to work within the system of fractions we can adjust for.

If you have a better solution please post it with all the accompanying math. We want to avoid Constants and Dividing etc. So if it's just a variant on the USMC Method or Hoffman Formula, we already know about that and want to avoid that level of thinking. We get these old formulas work but are cumbersome.

This is the opening of the door for a better mousetrap

 

[Rocketvapor]

I like the simplified approach to MOA.
Your Idea applies well to my 88 ELD at 2880 (2.5 sight height)
3 MPH Wind
Calculated --- Rounded for 1/4 MOA Clicks
100 = .18 -----0 clicks (hold a hair)
200 = .35 -----1 click
300 = .54 -----2 clicks
400 = .74 ------3 clicks
500 = 0.96 -----4
600 = 1.19 ----- 5
700 = 1.44 -----6
800 = 1.70 -----7
900 = 1.99 -----8
1000 = 2.29 ----9
1100 = 2.61 (I wish ) ----10

Rounding loses some when going to 6 mph.

 

[C_R_Slacker]

This method works as well as the mil version, but i still prefer doing it in mils. One reason is more than likely your gun is not going to be a perfect 2, 3, or 4 mph gun in this moa version. It's going to be somewhere in between the nice whole numbers.

The same is true for the mil version. You're probably going to be somewhere in between a 4, 5, or 6 mph gun. But, in the mil version you are rounding a lot less to get to a nice whole number for your base wind. Those rounding errors get compounded when you start adjusting for changes in wind speed and direction.

 

[Deleted member 113831]

I posted this in the other thread, but I will re-post it here. These are a couple of different variations of what I have used in the recent past. It is applying the BC/MILS methodology to the MOA problem.

Given: At 1000 yards, with the bullets and cartridges we are using these days, 1mph full value wind = +/- 1/2 MOA.

So, take your bullet number that respresents your base wind from the BC/MIL method, your "5","6","7" or "8"... and drop it by one number. So a "6" becomes a "5". This is your MOA base wind. This wind moves your bullet 3 MOA at 1000 yards.

1 MIL is 3.438 MOA, so we are basically getting rid of the 0.438 and dividing 3 MOA by 10 to get 0.3 MOA per hundred yards.

Multiply the yard line by 0.3 (example: 900 yards is 9 x 0.3 = 2.7 MOA)

If the wind is 2x the base wind, multiply by 0.6 (example: 9 x 0.6 = 5.4 MOA) ...and so on.


ALTERNATE METHOD: USE AN ANGLE OF 5 MOA
Find the wind that moves your bullet 5 MOA at 1,000 yards. This will be approximately 150% of your MIL number, and will give 1/2 MOA per 100 yards. Just multiply the yardline by 0.5 ( 800 yards would be 4 MOA)

Of course doubling this number will give you 1 MOA per hundred for 10 MOA at 1,000 yards.

 

[beetroot]

So basically what your saying is just use Mrad?
Just run the numbers with my loads and the rule works out perfect.

I hope there are more Mrad hunting scopes and Shot next year......

 

[seansmd]

I posted this in the other thread, but I will re-post it here. These are a couple of different variations of what I have used in the recent past. It is applying the BC/MILS methodology to the MOA problem.

Given: At 1000 yards, with the bullets and cartridges we are using these days, 1mph full value wind = +/- 1/2 MOA.

So, take your bullet number that respresents your base wind from the BC/MIL method, your "5","6","7" or "8"... and drop it by one number. So a "6" becomes a "5". This is your MOA base wind. This wind moves your bullet 3 MOA at 1000 yards.

1 MIL is 3.438 MOA, so we are basically getting rid of the 0.438 and dividing 3 MOA by 10 to get 0.3 MOA per hundred yards.

Multiply the yard line by 0.3 (example: 900 yards is 9 x 0.3 = 2.7 MOA)

If the wind is 2x the base wind, multiply by 0.6 (example: 9 x 0.6 = 5.4 MOA) ...and so on.


ALTERNATE METHOD: USE AN ANGLE OF 5 MOA
Find the wind that moves your bullet 5 MOA at 1,000 yards. This will be approximately 150% of your MIL number.

If your MIL number is a "5" then this new number is about a "7", if the MIL number is a "6" then use "9". This number will give you 1/2 MOA per hundred. Of course doubling this number will give you 1 MOA per hundred for 10 MOA at 1,000 yards.

This is my 6.5cm 130g prime with 5mph wind.

 

[sinister]

I mentioned in the earlier (now deleted) thread that it doesn't matter what math and constants you use, you need to be able to do it fairly quickly and accurately should your electronic crutch (your telephone) ever runs out of power.

Spend tens of thousands of dollars (in gear, food, gun, scope, guide, tickets, and lodge) for that once-in-a-lifetime Moose (or whatever) hunt to the Rockies, Canada, or Alaska to have it go into the toilet for want of battery power (or it got wet or you dropped it) and you're hosed.

Sad face.

It's math. Pick your formula and constants, then do it long-hand. Understand it. Once you're proficient, tuck it away and use your Apple, Android, Mongoloid, abacus and beads, whatever. Keep a cheater card so you don't forget or leave a step out, or forget your constants or formulas.

Know what you're going to use. Use it, shoot it, log it. Be absolutely confident it's going to work. Don't rely on a machine that can fail.

 

[Deleted member 113831]

I mentioned in the earlier (now deleted) thread that it doesn't matter what math and constants you use, you need to be able to do it fairly quickly and accurately should your electronic crutch (your telephone) ever runs out of power.

I think that either of these two methods presented above by @C_R_Slacker or myself accomplish exactly that. What's more, in all of my study to date, I have never seen either one in print. So, I am grateful these conversations happen so that some new light gets shed on old problems.

 

[Subwrx300]

What type of precision are we shooting for with an MOA wind quick conversion? Is +-.25 sufficient? And if so, should this work at all elevations/temps?
I tinkered with a spin on Frank's formula/G1 and came up with a way to account for BC, Temp and altitude but I need to play with it more this weekend.

 

[Deleted member 113831]

@Subwrx300

I need to play with it in MOA a bit more also. But in MILs I have found that the BC/MIL method is the truest with a bullet at 2800 fps at 2000ft elevation.

Tweaks to line it up at other speeds and elevations as follows:
A) 200 fps = 1mph basic wind change. So a bullet that is a "5" becomes a "6" at 3000fps and a "4" at 2600fps.

B) 4000ft elevation change = 1 mph basic wind change. A "6" at sea level becomes a "7" when shooting with @Lowlight on his range.

Changes can be either offsetting or cumulative.

 

[Lowlight]

@sinister

We are trying to simplify the explanation when we teach this stuff, and give people a better shortcut/rule of thumb than the long hand math and use of constants

We know we can use constants with MOA adjustments and it works great, but not everyone knows those constants or where to find them. Sure the Math is easy, then why isn't everyone better at using it ?

The way the information is presented or not is the issue we are trying to solve

 

[sinister]

Makes sense. They may still have to keep cheater cards -- as Skookum notes there are exceptions for density altitude and velocity changes.

Kinda like mass-produced weapons and ammunition -- tolerance stacking can mean a miss. Of course, then you can use all the fancy hashes on your modern reticle to do follow-up shots (instead of killing your target outright).

It all comes back to the individual shooter's proficiency at judging distance (for the come-up), density altitude change (higher or lower impact), wind velocity and direction (your "Push" from no-wind), and your math skills (using your known projo velocity at respective distances, and bullet drag factor).

 

[Subwrx300]

@Subwrx300

I need to play with it in MOA a bit more also. But in MILs I have found that the BC/MIL method is the truest with a bullet at 2800 fps at 2000ft elevation.

Tweaks to line it up at other speeds and elevations as follows:
A) 200 fps = 1mph basic wind change. So a bullet that is a "5" becomes a "6" at 3000fps and a "4" at 2600fps.

B) 4000ft elevation change = 1 mph basic wind change. A "6" at sea level becomes a "7" when shooting with @Lowlight on his range.

Changes can be either offsetting or cumulative.

Tried sending you a PM about this to discuss but couldn't get it send. Looks like your PMs are off.

 

[Deleted member 113831]

Tried sending you a PM about this to discuss but couldn't get it send. Looks like your PMs are off.

Pm sent

 

[300ATT]

Simple.

Step 0:
Just have students figure what "wind cheater" value their gun/cartridge is (Lowlight's example - "5 MPH gun")

Step 1: Determine your base wind-hold number is at distance (5 mph) : use 1/3 MOA for each 100 yards, and round to nearest .25 MOA and ADD an extra .25 MOA starting at 700 yards for rounding errors)

Step 2: Figure out the "real wind factor" by dividing the observed wind value by the "wind cheater" factor (e.g. 10 mph wind (full value) / 5 mph wind cheater value = 2.0 real wind factor)

Step 3: Multiply the numbers from steps 1 and 2 (base wind-hold number by the real wind factor to get your wind dope).

Example:

Step 0: Assume a gun/cartridge with a 5 mph "wind cheater" factor
Assume a 10 mph right quartering crosswind (3/4 value)
Assume a target at 700 yards

Step 1: Determine your base wind-hold number using the wind-cheater number (5 mph). Use 1/3 MOA for each 100 yards and round to the nearest .25 MOA ( In other words in stead of .1, .2, .3 Mils at each 100 yards use 1/3 MOA and round to nearest .25 MOA) giving us the following values:

200 yds = 2* 1/3 or .75 MOA

300 yds = 3* 1/3 = 1.0 MOA

400 yds = 4*1/3 = 1 and 1/3 or 1.25 MOA

500 yds = 5*1/3 = 1 and 2/3 or 1.75 MOA

600 yds = 6 * 1/3 = 2.0 MOA

**** Note starting at 700 yards you should add an extra .25 MOA to deal with rounding errors ****

700 yds = 7*1/3 = 2 and 1/3 or 2.25 MOA + .25 MOA (extra) or 2.5 MOA

800 yds = 8*1/3 or 2 and 2/3 or 2.75 + .25 MOA(extra) or 3.0 MOA

900 yds = 9 * 1/3 or 3 MOA + .25 MOA(extra) = 3.25 MOA

1,000 = 10 * 1/3 or 3 and 1/3 MOA or 3.25 + .25 = 3.5 MOA

(BTW the above numbers can be memorized because they DON'T change. )

Step 2: Get your real wind factor: 10mph*3/4 = 7.5mph -> 7.5 mph (observed wind) / 5 mph (wind cheater value) = 1.5 real wind factor

Step 3: multiply the 700 yard base wind cheater number (2.5 MOA) by the real wind factor of 1.5 to get 3.75 MOA

... this will get you really close within 1/4 MOA ...

... now send it

PS: you will need to add additional .25 MOA increments as you stretch the distance beyond 1,000 due to rounding errors and bullet slowing down (they seem to "hit a wall" at about 1,800fps and 1,100 fps in the software).

 

[Lowlight]

I am not sure I am tracking the above,

here is some data, this is a 6.5 with 143s at 2800fps

We see it lines up in Mils but now establish this same ease with MOA

Edited to add the 5MPH Version for MOA, the above is 6MPH

 

[300ATT]

You will get some anomalies (within 1/4 MOA) due to rounding errors and the fact that you can't dial a MOA scope .9 MOA . Also the difference between a 5mph gun and 6 mph is significant ... start adding the extra .25 MOA beyond 700 yards.

Perhaps a better approach to try (not sure this is a good idea) is to play with numbers that come out of the ballistic calculator to find the "wind-cheater" speed where every 100 yards is 0.5 MOA more of wind hold (e.g. o.5 moa at 100 1.0 moa at 200 ... etc.) this would be a higher windspeed than used for .1 mil at 100 etc. It would be something like (7-10 mph) but could work. When i do this for my .260 I get a "wind-cheater" speed of 5 mph that gives me .1, .2, .3 ... mils every 100 yards and using 8 mph I get .5 MOA, 1 MOA, 1.5 MOA every 100 yards ... that is a lot easier than the 1/3 MOA approach I listed above ...

Like I said this approach needs to be looked at closely ...

 

[300ATT]

Did some more playing. I think the best way to explain this is exactly the same way you do for guys with mils scopes. Play with the ballistic software to find a direct crosswind value that will displace the bullet 0.5 MOA every 100 yards - this is your "wind-cheater" value for your MOA scoped rifle. This seems to work within the resolution of 1/4 MOA knobs and is A LOT easier to explain than that 1/3 MOA approach I listed earlier.

 

[C_R_Slacker]

Did some more playing. I think the best way to explain this is exactly the same way you do for guys with mils scopes. Play with the ballistic software to find a direct crosswind value that will displace the bullet 0.5 MOA every 100 yards - this is your "wind-cheater" value for your MOA scoped rifle. This seems to work within the resolution of 1/4 MOA knobs and is A LOT easier to explain than that 1/3 MOA approach I listed earlier.

I played with this a little, but i can't get it to line up. Having to remember to add a quarter after xxx yards or a half after xxx yards is harder to me than the method I've proposed. I think the reason pegging your wind value to 500 yards works so well is because you're averaging your rounding errors to an intermediate distance instead of the extremes of 100 or 1000 yards.

 

[Deleted member 113831]

@300ATT

That is basically the "0.3 x yard line" formula I posted above in post #4, with 2 differences. You are doing the math using fractions and rounding to the nearest .25 moa. That formula will give you the 1/3 moa per 100 yards if you drop the basic wind number down one number. So it would be G1 BC -1.

 

[Deleted member 113831]

I am not sure I am tracking the above,

here is some data, this is a 6.5 with 143s at 2800fps

View attachment 6989597

We see it lines up in Mils but now establish this same ease with MOA

Edited to add the 5MPH Version for MOA, the above is 6MPH
View attachment 6989604

This shows what I was saying, when you dropped the base wind 1mph to a "5", every single yard line lines up with .3 (1/3 moa) x yardline.

100 0.3 x 1= 0.3 moa
200 0.3 x 2= 0.6 moa
300 0.3 x 3= 0.9 moa
400 0.3 x 4= 1.2 moa
500 0.3 x 5= 1.5 moa
600 0.3 x 6= 1.8 moa
700 0.3 x 7= 2.1 moa
800 0.3 x 8= 2.4 moa
900 0.3 x 9= 2.7 moa
1000 0.3 x 10= 3 moa

So, as compared to your JBM data, we are within .25 moa all the way to 1000 yards.

 

[beetroot]

You will get some anomalies (within 1/4 MOA) due to rounding errors and the fact that you can't dial a MOA scope .9 MOA . Also the difference between a 5mph gun and 6 mph is significant ... start adding the extra .25 MOA beyond 700 yards.

Perhaps a better approach to try (not sure this is a good idea) is to play with numbers that come out of the ballistic calculator to find the "wind-cheater" speed where every 100 yards is 0.5 MOA more of wind hold (e.g. o.5 moa at 100 1.0 moa at 200 ... etc.) this would be a higher windspeed than used for .1 mil at 100 etc. It would be something like (7-10 mph) but could work. When i do this for my .260 I get a "wind-cheater" speed of 5 mph that gives me .1, .2, .3 ... mils every 100 yards and using 8 mph I get .5 MOA, 1 MOA, 1.5 MOA every 100 yards ... that is a lot easier than the 1/3 MOA approach I listed above ...

Like I said this approach needs to be looked at closely ...

I agree, whilst it can work there seems to be no simple rule such as as the take first digit of BC etc.
I've been doing this the last few days using Strelok in my spare time at work, just plugging in different wind speeds seeing which fits best.
I'm able to get my 260 load to work well out too 600/700yards within 1 click of error.

BUT, it just works better with MILs.

I think being base 10 it's just far easier to notice patterns (especially when it's easy like .1mil per 100m), you don't need to look at the numbers and round to the nearest .25moa click it's already in .1mil increments. Being a slightly coarse adjustment seems to help also.

 

[Subwrx300]

Had good convo with @Skookum and it spurred some ideas about combining his system with an idea I've been testing to find base with using both BCs (G1 and G7). It allows calculator less wind solutions. Zero zilch nada.

MOA WIND for Base Wind Value = (50%Target Distance)/100.

Base Wind Calculator:

• Add your G1 and G7 BCs together
• (Example: 140 ELD = .587+.301 = .888)
• Move decimal right one place (.888 = 8.8mph base)
• Correct for altitude by subtracting/adding .5mph per 1k change away from 2500ft.
• Example altitude corrections: 0ft = -1.25mph 500ft = -1mph, 1000ft = -.75mph, 4500ft = +1mph, 5500= +1.5mph, etc

In other words, take half the distance and move decimal left twice. This is just like converting IPHY or SMOA ranges/corrections.

Example: 800yds target = (800/2)= 400/100 = 4 moa wind hold for a base wind.

Example: 140ELD at 1000ft = 8.05mph base
Wind 400yds = 2moa per 8mph (AB says 1.8MOA)
600 = 3 moa per 8mph (AB says 2.85 MOA)
900 = 4.5moa per 8mph (AB says 4.7 MOA)

I ran the above mentally first using above method and then put in the calculator created to check:

Inputs:

I've run this with 69TMK, 77 SMK, 88 ELD, 123 SMK, 140 VLD, 140 ELDM, 175 SMK at various speeds and in all but extremes (very fast/light or super high elevation 5000+) it's within about +-1/2 moa on most bullets within the first 75% of supersonic flight. It will start to diverge a bit when approaching transonic range AND/OR when using midweight bullets for the caliber.

Thoughts?

 

[Subwrx300]

Here's a hand sketch for quick version:

 

[300ATT]

@Subwrz300, I like it.

I took the "hunt and peck" approach - entering different direct crosswind numbers in the ballistics software until I got a "wind-cheater" value that lined up with 1/2 MOA wind drift every 100 yards under a 1/4 MOA resolution.

I wonder if your approach to add the G7+ G1 numbers works across different long distant bullets/cartridges. It would not surprise me as software is driven by those inputs.

At the end of the day this method is an easy way to come up with a good "SWAG" for wind. Shooters will need to do some truing and a lot of field verification. But it is a great way to start.


This will work for the MOA guys. Its easy to explain and everyone can remember that 9 mph = 1/2 the distance in MOA wind call.

 

[Subwrx300]

@300ATT I ran it for several bullets in .224, 6.5mm and .308 Cal. Most worked perfectly but the midweight bullets for their diameter usually overestimated wind at shorter ranges (.75moa or so) and started lining up better at 30-40% of supersonic flight.

3-oh-hates understimate wind until you get to a 200gr bullet or so.

 

[300ATT]

I have yet to find software that doesn't underestimate wind for the 3-oh-hate. Easy fix:

Start off with start a lower wind cheater number ( 7mph ) and hold 1/2 the distance in MOA and use the "hunt and peck" method with software to fine tune the base number for your .308.

There is a noticeable difference in wind-cheating between my 16" .308 and 29" .308 Palma rifle ...

 

[Grog11]

Tag

 

[LawnMM]

Here's my take on this, with MILs I find the point where I'm at 1 MIL drift at 1k, winds up being 8mph and within a tenth lines up at all yard lines. So with an 8mph wind I'm at .4 at 400, .7 at 700, etc.

Then it's just a matter of multiplying or dividing based on conditions. If it's a 4mph wind then I'm at .2 at 400, .35 at 700, etc.

It's definitely weird with MOA, but if you find the point where it lines up at 500yds but twice the value, you can do the same thing. So for my gun 5mph gets me 1 moa at 500, 2.3 at 1k, etc. It's basically double the yard line. So at 300 it's 0.6 moa, 800 is 1.8 (1.6 is close enough).

It's not perfect but you're close enough if doing this on the fly via the quick n dirty approach, which I think is the goal, right?

If we're within a tenth of a MIL or one or two tenths of a minute, that's small enough a difference to be "in the noise"

If time and opportunity allow it, use a kestrel or a chart. If those aren't available for some reason, doing it this way with either system is simple and gets you damn close.

 

[Diver160651]

What gun is your 8 mph gun?

I find once I am seeing 8-9 mph guns they are fast mags or LM type. But on ELR guns, I find those to be a bit better to run off tuned solvers once we’re at the longer ELR distances.

Mil wind works best in that PRS style matches were the the majority of the targets are well under 1k and the time needed for a wind call might be short when you’re first up. BTW the average range would suprise a lot of shooters.

Most 6mm and 6.5’s that are running 3000+ are using mid 5BC offerings and those the extra 200fps makes them run as 6mph guns.

Rather than take the 1 mil at 1k, I find it makes more sence to use the solver to line up 1-8 then fudge on 9 if needed, because then it is simply add .1 to your base. Medium and short range wind being dead on is nice, because that tends to be where you’ll see a lot of diamond shape targets.. Any vertical variation due to wobble or speed and you end up with a plate that can be a 1/4 of the size in terms of wind.

 

[47guy]

Tag to read later

 

[LawnMM]

What gun is your 8 mph gun?

I find once I am seeing 8-9 mph guns they are fast mags or LM type. But on ELR guns, I find those to be a bit better to run off tuned solvers once we’re at the longer ELR distances.

Mil wind works best in that PRS style matches were the the majority of the targets are well under 1k and the time needed for a wind call might be short when you’re first up. BTW the average range would suprise a lot of shooters.

Most 6mm and 6.5’s that are running 3000+ are using mid 5BC offerings and those the extra 200fps makes them run as 6mph guns.

Rather than take the 1 mil at 1k, I find it makes more sence to use the solver to line up 1-8 then fudge on 9 if needed, because then it is simply add .1 to your base. Medium and short range wind being dead on is nice, because that tends to be where you’ll see a lot of diamond shape targets.. Any vertical variation due to wobble or speed and you end up with a plate that can be a 1/4 of the size in terms of wind.

6x47L with 115 Dtacs at just under 3k, it's not the custom curve though so that might be off a touch, was just using it to check how it all lined up

Everybody has their own twist on this, I'd rather be off a tenth at 400 where it's only a difference of an inch and a half than at 1000 where it's three and a half

Everybody can set it up to bias it in whatever direction they want by playing with the speed

 

[Seymour Fish]

Okay, rather than chase the details in that Mil vs MOA thread I am starting a new one with the math being discussed for using a single MPH with MOA like we do with Mils.

History,

We are a Base Wind / MPH which translates very well in Mils to our wind doping. There are multiple threads on the subject, but in simple terms:

First Number of the G1 BC gives the shooter his base wind for that bullet being used in MPH.

6.5 G1 BC of .545 would equal at 5MPH Gun. That translates to:

200 = .2
300 = .3
400 = .4
500 = .5
600 = .6 Mils

This for 5 MPH wind, a 10 MPH would be double the value, so 500 yards @ 10 MPH = 1 Mil Wind Hold

The MOA solutions are not so simple, and we have several variations on the methods. The British Method, the USMC Method, and the use of Constants which can vary from Caliber to Caliber. In the interest of creating an easier solution that does not require longhand math a bunch of guys have put their heads together to simplify the process for guys shooting scopes based in MOA.

While we have different methods to address the same subject, it's about teaching new shooters to understand the methods and not have to break out calculators in the field. Many guys will default to simple charts carried and this works great. It means you only do the math once and then you read the results as necessary. But still we wanted a method that works the same as Mils.

Fractions vs Base 10 is the issue and why we have a daily debate, Mils vs MOA for long range shooting.

One of the answers we have hit on, thanks to a couple members, including @C_R_Slacker was to use the MPH method were the wind equals 1 MOA @ 500 as your base wind. For our example using a modern caliber (VS the old 168gr 30-8 stuff that is everywhere for MOA shooters) was to translate the Mil Data to MOA. This cuts the wind in 1/2 but lines the data up in a logical order.

3 MPH Wind for my 6.5 143 Data:

100 = .2
200 = .4
300 = .6
400 = .8
500 = 1.0
600 = 1.25
700 = 1.5
800 = 1.75
900 = 2.0
1000 = 2.5
1100 = 2.75

This becomes your base hold which is adjusted for your system and caliber, after that it is just a cosine or addition. Same as using Mils. We want to round the values to actual adjustments so you might see .3 MOA rounded to .25 and .4 rounded to .5 MOA because that is how our scopes adjust. We have to work within the system of fractions we can adjust for.

If you have a better solution please post it with all the accompanying math. We want to avoid Constants and Dividing etc. So if it's just a variant on the USMC Method or Hoffman Formula, we already know about that and want to avoid that level of thinking. We get these old formulas work but are cumbersome.

This is the opening of the door for a better mousetrap

If you want crude and quick, given a reasonably large target, try this: 10 mph cross wind in the field, so plenty uncertainty Mule deer at 600. Multiply previous 100 yd increment by target range. 500 x 600 = 30 (droop the zeros) inches. 30 inches is roughly 5 MOA. 30/6. This works for most of the average hunting rigs with nothing special BC’s. For a 6.5 SAUM or suchlike, simply reduce the number by roughly 30% = 3.5 MOA. In your head, in about 3 seconds. Easy to test and prove up on targets at various distances with a specific rig to perfect your %age fudge factor

 

[Diver160651]

6x47L with 115 Dtacs at just under 3k, it's not the custom curve though so that might be off a touch, was just using it to check how it all lined up

Everybody has their own twist on this, I'd rather be off a tenth at 400 where it's only a difference of an inch and a half than at 1000 where it's three and a half

Everybody can set it up to bias it in whatever direction they want by playing with the speed

Lawb, run your numbers again somethings not right I ran my 6mm at 3050 with the 115s snd our range 28.9inHg is still a 6mph gun..

 

[Subwrx300]

Lawb, run your numbers again somethings not right I ran my 6mm at 3050 with the 115s snd our range 28.9inHg is still a 6mph gun..

That's what I was thinking. Unless he is at high elevation and temps, 9mph seems like too much. I've run a couple dozen bullets now and generally for MOA values:

• 223 (60-77gr) = 4-5mph
• 224V (85-95gr = 5-6mph
• 6mm 105-125gr = 6-7mph
• 6.5mm 130-147= 8-9mph
• 308 175 -215s = 7-8mph

Unless he is referring to the Mil values but even then...

 

[Diver160651]

That's what I was thinking. Unless he is at high elevation and temps, 9mph seems like too much. I've run a couple dozen bullets now and generally for MOA values:

• 223 (60-77gr) = 4-5mph
• 224V (85-95gr = 5-6mph
• 6mm 105-125gr = 6-7mph
• 6.5mm 130-147= 8-9mph
• 308 175 -215s = 7-8mph

Unless he is referring to the Mil values but even then...

It is way too much at his <3kfps with a .5BC Dtac more like a faster 338 or 300 norma—

 

[Namekagon]

This method works as well as the mil version, but i still prefer doing it in mils. One reason is more than likely your gun is not going to be a perfect 2, 3, or 4 mph gun in this moa version. It's going to be somewhere in between the nice whole numbers.

The same is true for the mil version. You're probably going to be somewhere in between a 4, 5, or 6 mph gun. But, in the mil version you are rounding a lot less to get to a nice whole number for your base wind. Those rounding errors get compounded when you start adjusting for changes in wind speed and direction.

This is EXACTLY what I’ve been playing with since learning the MIL method, but I never shared it because I haven’t tested it much with live fire. Great to see I’m not alone with this.

For my 6XC, with a base wind of 4mph, drift at 500 is 1moa according to Shooter.

Which makes the wind call for each yard line twice the yard line in tenths.

At base wind, 600 yard wind call would be 1.2 moa. App calls for 1.3 moa.

App indicates this method is spot on up to about 8-900 yards. Then it starts to underestimate wind, need to add a click.

 

[LawnMM]

MIL values at 24 baro it lines up in my app at 8mph. I don't really use this method or app, I like the Kestrel.

 

[Diver160651]

@LawnMM

The guys I know that started using wind and solvers and spread the word in matches. They used a 29ish InHg to find base wind so it was easy to travel.

As you can see at 6000 feet above sea level or 24inhg, if one tried to use the BC method without understanding the base it would be wrong.

So ya, my 6mph gun becomes a 7 about 26ish and at 24ish an 8 but the guys I learned this from still call their guns by the base wind at 29ish aka 6mph gun.

I think this is a bit like using adjusted barro it helps us all communicate at a base level. I am not suggesting we switch from station, for our solutions, just that if we are going to communicate in a common fashion, mil wind should be distilled to the base formula.

I hope this makes sence, but you have a 6mph system. Where you shoot you need to modify it to a greater value.

 

[Seymour Fish]

Okay, rather than chase the details in that Mil vs MOA thread I am starting a new one with the math being discussed for using a single MPH with MOA like we do with Mils.

History,

We are a Base Wind / MPH which translates very well in Mils to our wind doping. There are multiple threads on the subject, but in simple terms:

First Number of the G1 BC gives the shooter his base wind for that bullet being used in MPH.

6.5 G1 BC of .545 would equal at 5MPH Gun. That translates to:

200 = .2
300 = .3
400 = .4
500 = .5
600 = .6 Mils

This for 5 MPH wind, a 10 MPH would be double the value, so 500 yards @ 10 MPH = 1 Mil Wind Hold

The MOA solutions are not so simple, and we have several variations on the methods. The British Method, the USMC Method, and the use of Constants which can vary from Caliber to Caliber. In the interest of creating an easier solution that does not require longhand math a bunch of guys have put their heads together to simplify the process for guys shooting scopes based in MOA.

While we have different methods to address the same subject, it's about teaching new shooters to understand the methods and not have to break out calculators in the field. Many guys will default to simple charts carried and this works great. It means you only do the math once and then you read the results as necessary. But still we wanted a method that works the same as Mils.

Fractions vs Base 10 is the issue and why we have a daily debate, Mils vs MOA for long range shooting.

One of the answers we have hit on, thanks to a couple members, including @C_R_Slacker was to use the MPH method were the wind equals 1 MOA @ 500 as your base wind. For our example using a modern caliber (VS the old 168gr 30-8 stuff that is everywhere for MOA shooters) was to translate the Mil Data to MOA. This cuts the wind in 1/2 but lines the data up in a logical order.

3 MPH Wind for my 6.5 143 Data:

100 = .2
200 = .4
300 = .6
400 = .8
500 = 1.0
600 = 1.25
700 = 1.5
800 = 1.75
900 = 2.0
1000 = 2.5
1100 = 2.75

This becomes your base hold which is adjusted for your system and caliber, after that it is just a cosine or addition. Same as using Mils. We want to round the values to actual adjustments so you might see .3 MOA rounded to .25 and .4 rounded to .5 MOA because that is how our scopes adjust. We have to work within the system of fractions we can adjust for.

If you have a better solution please post it with all the accompanying math. We want to avoid Constants and Dividing etc. So if it's just a variant on the USMC Method or Hoffman Formula, we already know about that and want to avoid that level of thinking. We get these old formulas work but are cumbersome.

This is the opening of the door for a better mousetrap

Wind drift is Parabolic, just like drop. This is being ignored and leads to those mysterious “shucks gotta add an extra number or two” comments beyond a certain yardage. Get off the linear

 

[C_R_Slacker]

Wind drift is Parabolic, just like drop. This is being ignored and leads to those mysterious “shucks gotta add an extra number or two” comments beyond a certain yardage. Get off the linear

I think everyone understands this. The whole discussion is to have a good enough method for a quick and dirty way of correcting for the wind. That's why we all fudge the numbers one way or another to make it line up in a way that is easy to remember and apply in the field. There is the bc mil method that everyone knows, and two or three proposed moa methods that all work well enough to keep you within .1 mil or .25 moa from 100 to 1000. The method is better than my ability to actually call the wind in the first place.

 

[Namekagon]

Something about lining things up at 500 yards is what makes it work. I originally tried other yardages after I found the 500 yd thing, couldn’t get anything else to work.

I do wonder how universal it is. When I tried to apply it to my 270 WSM, it worked, but didn’t lift up st 500 well, more like 450. A lot more error at each yard line.

 

[Namekagon]

Something about lining things up at 500 yards is what makes it work. I originally tried other yardages after I found the 500 yd thing, couldn’t get anything else to work.

I do wonder how universal it is. When I tried to apply it to my 270 WSM, it worked, but didn’t lift up st 500 well, more like 450. A lot more error at each yard line

 

[Deleted member 113831]

Wind drift is Parabolic, just like drop. This is being ignored and leads to those mysterious “shucks gotta add an extra number or two” comments beyond a certain yardage. Get off the linear

It is parabolic, but it just so happens that within a rifles supersonic range, the difference between the parabolic arc and the linear angle is too small to actually be seen on the target until you start dealing with 4 or 5 multiples of the base wind.

 

[Lowlight]

I love how people want to shut down the conversation , like it's offensive to think.

They act like they know something we don't , but immediately demonstrate their ignorance on what we are even discussing.


News Flash
We understand exactly how this works, apparently more so than you .

Try reading more and speaking less cause if you clutter up this thread you're gone.

 

[TheGerman]

I love how people want to shut down the conversation , like it's offensive to think.

They act like they know something we don't , but immediately demonstrate their ignorance on what we are even discussing.


News Flash
We understand exactly how this works, apparently more so than you .

Try reading more and speaking less cause if you clutter up this thread you're gone.

I think its that after years of being repeatedly told 'dont do math at the range' and 'if you're doing math while you're shooting you're stupid' as well as 'stop over-complicating simple shit with range math' everyone is now confused by 2 separate, completely random threads on 'lets do some range math'.

 

[Lowlight]

But it's not, it's a way of simplifying this the same way we see in mils.

The math for MOA shooters is different, so we are looking to create another level of ease versus doing "long hand math" which dominates wind with an MOA scope. There is no real shortcut.

If you can't understand the difference, stop commenting and move along. Doing something because it's always been done a certain way doesn't make it the only way. Range math is also different from formulas that require constants and extra steps.

Counting from 1 to 10 is not really math now is it, if you understand the context of the discussion you'd stop playing word games

 

[Diver160651]

I think its that after years of being repeatedly told 'dont do math at the range' and 'if you're doing math while you're shooting you're stupid' as well as 'stop over-complicating simple shit with range math' everyone is now confused by 2 separate, completely random threads on 'lets do some range math'.

Actually, we really not doing much math with mil wind; that is kinda the point. It really is the fastest simplest solution with least steps or math than anything today.

Taking something like 400y and saying .4 for your base wind does not really “feel” like math. If the wind is in one of those less than FV or going cutting it in half in not really difficult, nore is 2x the wind. I guess is technically math.. but it is as simple as it gets, way more simple than digging out my Kestrel and entering the yardage, capturing the target azimuth, then doing the same for wind and then, finally going back to the main screen seeing the solution.

It is as simple if not more so than looking at our range cards.

But 2 things people need to remember.

1 this is for your prediction not your correction. So I think any statement that’s been said previously in regards to corrections still holds true.

2. This is best suited and said many times for environments like positional shooting matches where there is a premium on time, problem solving and were the average distance is well under 1k.

 

[Namekagon]

Not sure if someone else pointed this out, I haven’t read every post in the thread in entirety. Was just playing with Shooter. It looks like, at least for me, I can use 2mph wind, instead of 4. This makes my wind call exactly like the MIL method, i.e. 300=0.3, 500=0.5 moa, for a base wind of 2 mph. It doesn’t get easier than that.

 

[C_R_Slacker]

Not sure if someone else pointed this out, I haven’t read every post in the thread in entirety. Was just playing with Shooter. It looks like, at least for me, I can use 2mph wind, instead of 4. This makes my wind call exactly like the MIL method, i.e. 300=0.3, 500=0.5 moa, for a base wind of 2 mph. It doesn’t get easier than that.

Right, it's the same concept so it works. That's where playing with different numbers within the same concept help you find something that lines up well for your rifle/ammo combination that you can easily remember and apply.