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  • Apr 12, 2001
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    The gun mph system is the fastest way to dope our rifle for wind.  It is easy, intuitive, and very quick once we get the hang of it.  It’s great for making an initial wind call and for reverse calculating what the actual wind speed is. (If you are not familiar with the Gun MPH system and what its wind brackets are, I suggest reading the Managing the Wind article about this system.) If we miss our first shot from a bad wind call, then make a correction and hit our target, we can reverse calculate to know what the cross wind speed and the actual wind speed are.  Here is an example of that process.



    Example 1:



    Target at 400yds. Initial wind call is 0.8 mil right for the wind we measured (15mph at 1:00) for our 5mph gun.First shot = miss off right edge (too much wind hold).We observe the miss splash and see it is 0.4 right of the target center.Move to 0.4mil right to center and send the...

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    "...and a little mental math..."

    0.7 x 1.4??? my brain melted down. I guess not too hard. 98 but still.

    F ME!!

    Playing around sure. On the clock?

    Man maybe I should play with this because I do struggle adjusting wind for ranges and angles...


    hmmm....
    DT
    I'm not an expert at mental math so I cheat on things like this. For example in this case I'd round up to 1.5 from 1.4 if doing this in the field. Then it's just adding .35 to .7 to get a 1.05 hold that you know is strong so round down.
     
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    Damn! That's a good Idea!
    FOR THE LOVE OF GOD PLEASE COPYWRITE AND TRADEMARK THIS BEFORE SOMEONE (he knows who he is) takes it and claims credit

    I’m calling it now, this will be in the military manuals at some point. It’s so much better than what’s been in there for the past 40 years.
     
    I shot a match today and for the first few stages I was relying on my Kestrel AB for wind holds, they were way off (not enough windage). So I switched it up and started using my rifle MPH and the wind rose and almost cleaned the long distance stage with a 16mph wind at 10:30. I shot the rest of the match much better using that chart.
     
    Question. I used my kestrel to figure out my gun number. Using the wind rose and comparing it to my kestrel the wind holds do not match. Should the wind rose give the same wind hold as the kestrel ?
     
    Example. My gun number using my kestrel came out to a 5mph gun. So I plugged in the mph on the wind rose. Now using my kestrel I put in 5 mph at 600 yards with a 130 wind. Using the wind rose it would be 0.7 x 0.6. The results the kestrel gives me are not close to what the wind rose gives me. I may or may not be calculating my mph number correctly in the kestrel. I basically set my wind direction to 9:00 and set my yardage to 600 and adjusted wind mph until my wind hold was .6 ( I did notice that the hold at 9:00 and 3:00 was not the same.)
     
    One of my shooting buddies taught me gun MPH a few years ago, and I've used it ever since.

    Only thing that ever made sense to me regarding wind calling. Bracketing and other methods just made my head hurt.
     
    I'm definitely going to try this out this weekend when I go out and practice. Calling wind is where I lose a lot of points. Especially on targets where first round impact really matters due to lack of berm to show where you missed. It has finally clicked after reading it 10 times!
     
    Someone please check my numbers in this. I think i get it but not certain
    I have a 5 mph gun
    Target @560 yds
    7mph wind from 7:30 on the rose
    .56x .75=.42 hold.
    Is this correct? Or do i have things all jacked up

    Thanks in advance
     
    Someone please check my numbers in this. I think i get it but not certain
    I have a 5 mph gun
    Target @560 yds
    7mph wind from 7:30 on the rose
    .56x .75=.42 hold.
    Is this correct? Or do i have things all jacked up

    Thanks in advance
    Here is the solution I get for a first wind call.
    5mph gun with 7mph wind at 7:30. 560yd target.
    Turn wind angle to 9 o'clock cross wind = 7mph x .7 = 5mph crosswind
    Gun mph wind bracket = 5mph/5 mph gun = 1.0 bracket
    560yd wind hold at 5mph =0.5mil (or round up to .6)
    0.5 hold x 1.0 bracket = 0.5 wind hold.

    The wind rose in this article is about relating your first shot direction to your 2nd shot direction. Not about making an initial wind call like you asked about. The CORRECTED CROSS WIND SPEED BRACKED should be used for the initial wind call.
    Let me know if this clears it up.
     
    Someone please check my numbers in this. I think i get it but not certain
    I have a 5 mph gun
    Target @560 yds
    7mph wind from 7:30 on the rose
    .56x .75=.42 hold.
    Is this correct? Or do i have things all jacked up

    Thanks in advance
    Let's try this again using the wind rose above. Yes it can be used for initial wind calls.
    Using the 5mph bracket rose (5-10-15-20-25 wind speeds) because we have a 5 mph gun we can fi. The wind bracket value for a 7 mph wind is between 5 and 10 mph. In the 7:30 pie shape we need to interpolate (guess) between 0.7 an 1.4. Since 7mph is nearly the middle between 5 and 10 I would say 1.0 is also nearly the middle of 0.7 and 1.4 (Interpolated)
    Hold = 0.56 x 1.0 = 0.56 mil.

    Where did you get the 0.75 from in your calculation?

    How I got to 1.0 bracket on gun mph wind bracket rose.
    1669128825265.png
     
    Hi, I'm trying to work out the advantages between the bracket rose and wind rose.

    When you're at a distance of 430 for example, do you round to one decimal place or two e.g. .4mil or .43mil?

    If you're using two decimal places for wind what advantage is there to the bracket rose vs the wind rose with a wind speed of 10?

    For example:
    A target at 430m, 16km/h wind at 4:00 with a 9km/h gun (the units don't mater).

    On the bracket rose 16 is just below bracket 18, go round to 4:00 which is 1.7 then round down to 1.6.
    0.43 x 1.6 = 0.7

    With wind rose and a 10km/h wind drift of 0.48. 15 goes round to 13 then round up to 14. 14/10 is 1.4.
    1.4 x 0.48 = 0.7

    It would seem the braket rose is easier to remember but the wind rose would be more precise at distance. Have I got this right or am I missing something?
     
    There aren’t a lot of scopes, if any that have .01 turrets. You’ll have to round.
    Hi, I'm trying to work out the advantages between the bracket rose and wind rose.

    When you're at a distance of 430 for example, do you round to one decimal place or two e.g. .4mil or .43mil?

    If you're using two decimal places for wind what advantage is there to the bracket rose vs the wind rose with a wind speed of 10?

    For example:
    A target at 430m, 16km/h wind at 4:00 with a 9km/h gun (the units don't mater).

    On the bracket rose 16 is just below bracket 18, go round to 4:00 which is 1.7 then round down to 1.6.
    0.43 x 1.6 = 0.7

    With wind rose and a 10km/h wind drift of 0.48. 15 goes round to 13 then round up to 14. 14/10 is 1.4.
    1.4 x 0.48 = 0.7

    It would seem the braket rose is easier to remember but the wind rose would be more precise at distance. Have I got this right or am I missing something?
     
    It’s to avoid rounding errors. If your wind value is 0.44 at 440 and the bracket is 4. 0.4 x 4 is 1.6 vs 0.44 x 4 which is 1.8.
    Right but most mil turrets don’t come in .01 increments and reticles don’t either. How just have to decide is it better to round up or down. That’s a personal choice.

    You could also just figure the halfway point of your 4 and 500 yard winds and use that
     
    Hi, I'm trying to work out the advantages between the bracket rose and wind rose.

    When you're at a distance of 430 for example, do you round to one decimal place or two e.g. .4mil or .43mil?

    If you're using two decimal places for wind what advantage is there to the bracket rose vs the wind rose with a wind speed of 10?

    For example:
    A target at 430m, 16km/h wind at 4:00 with a 9km/h gun (the units don't mater).

    On the bracket rose 16 is just below bracket 18, go round to 4:00 which is 1.7 then round down to 1.6.
    0.43 x 1.6 = 0.7

    With wind rose and a 10km/h wind drift of 0.48. 15 goes round to 13 then round up to 14. 14/10 is 1.4.
    1.4 x 0.48 = 0.7

    It would seem the braket rose is easier to remember but the wind rose would be more precise at distance. Have I got this right or am I missing something?
    I would round 430 yards to 0.4 Then if needed i could favor a tad strong (up wind) on the target, but this is not usually needed.

    There is no advantage or disadvantage to each wind rose when you are making your initial wind calls. Both of these can get you very close to the same wind hold as you demonstrated. Its crayons vd markers, choose the one that works best for you. The bracket rose will have an advantage when you start engaging multiple targets at different wind angles.

    These wind methods are meant to be quick and easy, so keeping the numbers simple is important. Choose the system the works for you mental computer and go with it.
     
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    Sorry for the dumb question but can this work with MOA? Any write up's with MPH gun and wind rose for MOA?
    Yes. this can work for MOA but there is an extra step and the values are a bit differnet.

    MIL System
    100 - 0.1 mil
    200 - 0.2
    300 - 0.3
    400 - 0.4
    500 - 0.5
    600 - 0.6

    MOA system
    100 - 0.5 moa
    200 - 1.0
    300 - 1.5
    400 - 2.0
    500 - 2.5
    600 - 3.0
    Simply divide you yardage in half then my 100. Example 550yds is 2.75moa (corrected my mistake) per wind bracket.

    Note: we cannot compare 2 rifles, one in moa and the other in MIL because the MOA gun number is usually 1.5x larger than the mil Gun Number for the same rifle. 6mph in Mil will be 9MPH in Moa. This larger Mile per hour value in MOA also make the chances for error larger and mental math larger. But, it can be done.

    Check out this post (post #7)
    https://www.snipershide.com/shooting/threads/mph-gun.6996049/post-8434111

    All of the wind roses work in MIL, MOA, MPH, m/s.. the roses are "unit-less" so any measuring system will work.
     
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    Yes. this can work for MOA but there is an extra step and the values are a bit differnet.

    MIL System
    100 - 0.1 mil
    200 - 0.2
    300 - 0.3
    400 - 0.4
    500 - 0.5
    600 - 0.6

    MOA system
    100 - 0.5 moa
    200 - 1.0
    300 - 1.5
    400 - 2.0
    500 - 2.5
    600 - 3.0
    Simply divide you yardage in half then my 100. Example 550yds is 2.25moa per wind bracket.

    Note: we cannot compare 2 rifles, one in moa and the other in MIL because the MOA gun number is usually 1.5x larger than the mil Gun Number for the same rifle. 6mph in Mil will be 9MPH in Moa. This larger Mile per hour value in MOA also make the chances for error larger and mental math larger. But, it can be done.

    Check out this post (post #7)
    https://www.snipershide.com/shooting/threads/mph-gun.6996049/post-8434111

    All of the wind roses work in MIL, MOA, MPH, m/s.. the roses are "unit-less" so any measuring system will work.
    In MOA, would 550 yards not be 2.75?
     
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    I get the MPH bracket in the rose, but where are the other numbers coming from (the columns with 1 o'clock ect) and what do they represent? Sorry if it's a dumb question.
    Starting at the inside of 1:00:
    The first column is the angle of 1:00, 30°.
    The second is the sine of the angle, sin(30) = 50% or 0.50.
    The third is 1x the sine value: 1 x sin(30).
    4th: 2 x sin(30).
    5th: 3 x sin(30) and so on.
     
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    Starting at the inside of 1:00:
    The first column is the angle of 1:00, 30°.
    The second is the sine of the angle, sin(30) = 50% or 0.50.
    The third is 1x the sine value: 1 x sin(30).
    4th: 2 x sin(30).
    5th: 3 x sin(30) and so on.
    Thank you for explaining that. That’s what I was looking for. I believe I understand now and it makes sense.
     
    […] MRAD unless if you are working wind in mph, then an MRAD scope also works better when you have your rifle’s wind number or your gun number. When you are using the imperial system, then usually you would go for the MOA reticle scope. This […]
     
    Let's try this again using the wind rose above. Yes it can be used for initial wind calls.
    Using the 5mph bracket rose (5-10-15-20-25 wind speeds) because we have a 5 mph gun we can fi. The wind bracket value for a 7 mph wind is between 5 and 10 mph. In the 7:30 pie shape we need to interpolate (guess) between 0.7 an 1.4. Since 7mph is nearly the middle between 5 and 10 I would say 1.0 is also nearly the middle of 0.7 and 1.4 (Interpolated)
    Hold = 0.56 x 1.0 = 0.56 mil.

    Where did you get the 0.75 from in your calculation?

    How I got to 1.0 bracket on gun mph wind bracket rose.
    View attachment 8004561
    Are the numbers on this chart "holds" and if so, for what range? Trying to understand because this "rose" looks different with the decimal numbers vs the wind values on the others.

    Thanks.
     
    They appear to be multipliers and not holds themselves.

    Using the pedigree info from the earlier the posts we're dealing with a 5 mph rifle, a target at 560 yards, and a 7 mph wind from 7:30.

    Using the "gen 1" wind rose with the corrected wind speed values a 7 mph wind from 7:30 would be 70% of the value. 7 X .7 = 5 mph. 5 mph rifle = a .56 (.6 mil hold)

    Using the "gen 2" wind rose with the multipliers it doesn't appear too different, instead of finding a corrected wind speed you're finding the multiplier that you'd use with the range, in this case .56 (560 yards). Using the info above in a similar way, trace along the rose to the point between 5 and 10 (.7 and 1.4 = roughly 1.0) Multiply the .56 X 1.0 = .56 mil wind hold.

    Another one would be a 700 yard target, same 5 mph rifle, and a 11 mph wind from 10:00. Follow the rose around and the multiplier is between 1.7 and 2.6, in this case 1.9 because there's a .18 bump per mph from 10 to 15 mph on the chart.

    .7 (700 yards) X 1.9 = 1.3 mil hold

    Using the Gen 1 rose the adjusted wind speed would be about 10 mph so 2 X .7 = 1.4 mil hold.

    Clear as mud?
     
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