Episode 70- where do you get initial wind hold?

[Nap Mag]

In this episode, they start off with a .5mil wind hold for 5mph at 500yards. Since it is caliber - specific, they use another caliber as an example at 39:15 in the podcast. That wind hold is 0.4 (for the 6br) - How did they get the number 0.4?

 

[Bugzlife19]

G1 BC for a 105 is in .4XX , so you take the first number of your G1 BC gives you your initial wind hold for 5mph.

 

[Deleted member 113831]

In this episode, they start off with a .5mil wind hold for 5mph at 500yards. Since it is caliber - specific, they use another caliber as an example at 39:15 in the podcast. That wind hold is 0.4 (for the 6br) - How did they get the number 0.4?

G1 BC for the 6mm heavy bullets is .5XX

So... the bullet is a "5". However, he is pushing it probably 2,900+fps AND he is probably at 5,000+ ft elevation, so that bullet becomes a very solid "6".

That means a 6 mph full value wind would push it 0.1mils per 100 yards, for a 0.5mil hold at 500, but they were only doing a 5mph wind, so the hold was 0.4mils.

 

[seansmd]

Sorry, seems simple but I am still missing the formula, I am using Prime 6.5 CM 0.583@2850, so what would be the initial hold for 5MPH full value hold at 500Y?

 

[Deleted member 113831]

0.4 or 0.5mils depending on altitude.

What part of it are you having trouble with?

 

[seansmd]

0.4 or 0.5mils depending on altitude.

What part of it are you having trouble with?

Where did you get the 0.1 to start with, how is it based on the 0.583 G1?

 

[Deleted member 113831]

The wind that pushes your bullet a total of 1 mil at 1000 yards.

1 mil at 1000 yards is 0.1 per 100 yards. So... 0.3 at 300... 0.5 at 500 ... 0.8 at 800 etc.

By happenstance, that wind is very closely represented by the first number of your G1 BC, if you are in the 2700-2900 fps velocity range.

Your bullet being a .583 G1 BC and moving out at a solid 2850 fps, makes yours right on the line between a "5" and a "6". Altitude increases a bullets BC, so at higher altitudes it takes slightly more wind to move them.

 

[Diver160651]

G1 BC for the 6mm heavy bullets is .5XX

So... the bullet is a "5". However, he is pushing it probably 2,900+fps AND he is probably at 5,000+ ft elevation, so that bullet becomes a very solid "6".

That means a 6 mph full value wind would push it 0.1mils per 100 yards, for a 0.5mil hold at 500, but they were only doing a 5mph wind, so the hold was 0.4mils.

Exactly—

I run a 547g1 but at 3055 and it runs as 6mph gun.

For those interested, the easiest way to see what your specific combo is to use your solver.

Disable all the gadgets SD etc and run wind at FV in your normal shooting conditions. Start at 5mph and see what gives you .1 per 100 until about 800/900

You’re going to need to make some concessions on were the actual brake to the next 1/10 is - don’t try to get to granular with the wind.. you’ll be really lucky just to get mph close.

Remember, the whole idea of mil wind is super fast and dirty starting point with little math —

 

[Hondo64d]

In this episode, they start off with a .5mil wind hold for 5mph at 500yards. Since it is caliber - specific, they use another caliber as an example at 39:15 in the podcast. That wind hold is 0.4 (for the 6br) - How did they get the number 0.4?

I just plug my load info into my Ballistic program and note what full value wind speed gives me .1 mil of drift per every hundred yards. With my load in current conditions, that’s about a 5mph wind out to 1k. On a hot summer day here, it’s about 6mph.

John

 

[Deleted member 113831]

I just plug my load info into my Ballistic program and note what full value wind speed gives me .1 mil of drift per every hundred yards. With my load in current conditions, that’s about a 5mph wind out to 1k. On a hot summer day here, it’s about 6mph.

John

That is the most precise way to do it. You won't end up with a round number though. If you are actually wanting exactly 1mil at 1000 yards, you will end up with an odd decimal. Which is good to know, if you have time to really do the math and get as close as possible. If you confine yourself to round numbers though, you will find that your first G1 BC number is most often the number you are looking for.

Obviously a .505 BC at 2700fps and a .583 BC at 2900fps are not the same wind hold. You have to realize that it is a sliding scale and fudge toward the closest round number. All of this is before considering altitude and angle, of course.

 

[Diver160651]

That is the most precise way to do it. You won't end up with a round number though. If you are actually wanting exactly 1mil at 1000 yards, you will end up with an odd decimal. Which is good to know, if you have time to really do the math and get as close as possible. If you confine yourself to round numbers though, you will find that your first G1 BC number is most often the number you are looking for.

Obviously a .505 BC at 2700fps and a .583 BC at 2900fps are not the same wind hold. You have to realize that it is a sliding scale and fudge toward the closest round number. All of this is before considering altitude and angle, of course.

Angle doesn't matter -- you always want straight line distance for wind

 

[Deleted member 113831]

Angle doesn't matter -- you always want straight line distance for wind

I was referring to wind angle to the direction of fire rather than slope. I should have been more clear.

 

[Diver160651]

I just plug my load info into my Ballistic program and note what full value wind speed gives me .1 mil of drift per every hundred yards. With my load in current conditions, that’s about a 5mph wind out to 1k. On a hot summer day here, it’s about 6mph.

John

John,

Maybe check your solver again.. I am not saying your logic is not solid, but run numbers where the majority of your shooting takes place and real temps.. then at the longer range add or subtract

Wind does't work exactly as drastically as drag.. as an example at 800 yards with my load - to go between a 5mph and 6mph gun by temp alone, with a .8 drift; I'd need the them to be 5° F to use 5mph and can still use 6mph .8 hold @ 120°F. Thats 115° temp swing -- Not many places I'd realistically, see those kinds of swings..

So rather than try to manage it that way, for me I might modify the yardage points on were it turns for the temp deference's..

Here is an example with my 6mph gun--

The real key here, is to look at the wind as mil wind -- NOT MPH.. Try to look at the wind and say hum, that's 1/2 mil wind, a 4/10s wind looking at your 800 yard target. The idea of estimating is a fast cheat.. self-spotting and seeing the correction even for the hit are key to the process.. So you then modify the original mil wind guess.

If I really need another 2/10s to be dead center, now I need to do the conversion by realizing .6 is 3/4 of my .8 mil wind, or by simply doing the 1/2 of thing - adding or subtracting over and over.. I'd know I am working with what is effectively 3/4 of my mil wind.. Now the rest of my calls start to be based that because it take wind angle out of the mix; Well, until the wind, distance or DOF (azimuth) changes. Of course you can always covert it to MHP if you want to use your solver and I'd then enter 4.5mph.

This is the same logic as NOT using MPH for movers, but mil lead..

 

[seansmd]

Ok, so I'm Strelok, this is what i have entered for my prime.

Which netted these results:

So for every 6.5mph increase I add 0.1 Mill up to 600 yards. Then do math on the reduction from full value if applicable?

So a 13mph 90 degree wind at 300 yards would be 0.62, tons to 0.6 wind correction.

 

[Diver160651]

Ok, so I'm Strelok, this is what i have entered for my prime.View attachment 6970449

Which netted these results:
View attachment 6970450

So for every 6.5mph increase I add 0.1 Mill up to 600 yards. Then do math on the reduction from full value if applicable?

So a 13mph 90 degree wind at 300 yards would be 0.62, tons to 0.6 wind correction.

No put in 6pmh what to you get -- completely forget about 1/2 mph stuff or this gets to0 complicated and can end up being slower than your solver

But ya-- in reality it is closer to a 5.75 gun but thats hard to half, quarter or use .75 value at least in my head - see above.

 

[Deleted member 113831]

Ok, so I'm Strelok, this is what i have entered for my prime.View attachment 6970449

Which netted these results:
View attachment 6970450

So for every 6.5mph increase I add 0.1 Mill up to 600 yards. Then do math on the reduction from full value if applicable?

So a 13mph 90 degree wind at 300 yards would be 0.62, tons to 0.6 wind correction.

Why did you use 6.5mph? You have your altitude set at sea-level, so I ran your numbers in Strelok and 5mph gives you 0.99mils at 1000 yards.

 

[Diver160651]

Why did you use 6.5mph? You have your altitude set at sea-level, so I ran your numbers in Strelok and 5mph gives you 0.99mils at 1000 yards.

ya, but then the bread and butter ranges will be off.. Personally, if I need to curve fit, fit I'd rather be money on 0-800 and add .1 for 900 and 1K -

If I get real data up closer then I can convert it to use in the solver for the distance.. for ELR or one range no time constraints shooting I would use the MPH traditional stuff as first course - but thats me

The fast mil wind for PRS and field matches is a set of compromises and information tweaks - mostly all you get is binos - big spotters for the ROs only.. That kinda where these ideas were pass around and shared.

Edited to add - I didn't run a solver - so I could be off.. but a 130 around 2900 fps using a 5mph FV the mil wind will be .1 light in those areas 300-800 yards- by all means correct me if I am guessing wrong..

 

[Deleted member 113831]

ya, but then the bread and butter ranges will be off...

Yes, they will be off...by 0.05 mils on average. So, at 500 yards that is a 0.9 inch difference. But if you forget to add the extra 0.1 at 1000 yards, you have a 3.6" error. We are splitting cunt hairs either way, but I would prefer on principle, to have any error at the closer ranges where it matters the least.

 

[Diver160651]

Yes, they will be off...by 0.05 mils on average. So, at 500 yards that is a 0.9 inch difference. But if you forget to add the extra 0.1 at 1000 yards, you have a 3.6" error. We are splitting cunt hairs either way, but I would prefer on principle, to have any error at the closer ranges where it matters the least.

Yeah, but that’s not what this whole fast head math thing, is about

All 99% of ranges we are shooting, this should be correct to just about 800 and 800 I need to question things a bit, 900 add .1 @ 1000 maybe two. And most of these matches (Despite having a few targets passed 1000) The average round is going to be captured in the correct hold offs

Again if you’re just long range shooting and going to approach a single target, it’s a different ballgame than why people started playing with this type of wind math.

The BC method is very similar and you can see just by looking at his BC but if he used 5.8 mile an hour wind he’s probably pretty damn close.. But again then it gets very hard to take a little bit of information we’re getting off the plates to stitch the whole picture together under time using numbers that don’t 1/2 and 1/2 again or divide easily in our heads

Man Siri kicks my ass. I had and it is a bunch of times and still wrong but close enough.

 

[Deleted member 113831]

I think you missed my point. Since 5mph gives him basically 1 mil at 1k, he can just use that and still figure 0.1 per 100yds. The amount he will be off at 500 to 800 yards is small enough to be of no consequence.

 

[Diver160651]

I think you missed my point. Since 5mph gives him basically 1 mil at 1k, he can just use that and still figure 0.1 per 100yds. The amount he will be off at 500 to 800 yards is small enough to be of no consequence.

I got your point.

I’m driving and talking into Siri. I believe you have His program, can you run it and see if he’s really off only 500? I believe he’ll be off at 3,4,5,6,7 and possibly 8 hundred using 5 mph on a 5.8 BC bullet going close to 2900.. Also remember each target is scaled.

If they are going to throw a 3/10 target into the mix It will absolutely be at the closer ranges.

308 out of most 24/26 inch barrel is going to be a 5mph gun.

 

[Deleted member 113831]

I got your point.

I’m driving and talking into Siri. I believe you have His program, can you run it and see if he’s really off only 500? I believe he’ll be off at 3,4,5,6,7 and possibly 8 hundred using 5 mph on a 5.8 BC bullet going close to 2900.. Also remember each target is scaled.

If they are going to throw a 3/10 target into the mix It will absolutely be at the closer ranges.

308 out of most 24/26 inch barrel is going to be a 5mph gun.

In terms of mils, he will be off the most, .08 mils at 4,5,600. That amounts to 1.1-1.7 inches.

At 800 it's 0.06 mils which is still 1.7 inches.

 

[seansmd]

Here's the 5.8, I used sea level because that is what the datasheet said the BC and Dara was derived.

 

[Diver160651]

In terms of mils, he will be off the most, .08 mils at 4,5,600. That amounts to 1.1-1.7 inches.

At 800 it's 0.06 mils which is still 1.7 inches.

Inches from the angular guy

 

[seansmd]

Here is the 6.0.... this is all paper analysis, i would then need to true my MV for my gun at my alt and adjust, correct?

 

[seansmd]

And by the way, not siri, but google locked in on something @Lowlight or @Mag1c-Mik3 said on a recent podcast and was translating like shit for 5 minutes from the audio coming through the bluetooth in the car. Too funny, even the big foot shit.....

 

[seansmd]

Skookum is right 5mph dials 0.99 at 1k.

 

[Deleted member 113831]

We are really splitting hairs here. You can obviously tailor your approach however you wish. Diver isn't wrong. His approach makes sense in a certain context. These are just small differences in druthers.

 

[bornhunter04]

I'm shooting 130 elds @ 2850 from a 6.5 it takes a 6mph wind to get a 1mil hold @ 1k. G1 is .554 according to the box. Does this seem like it lines up? Easy way to remember, 6/6/6 600 yds, 6mph, .6 mils?

 

[Deleted member 113831]

@bornhunter04 Do you live at, or about 4,000ft elevation per chance? That combo is a "5" at sea level.

 

[Diver160651]

Skookum is right 5mph dials 0.99 at 1k. View attachment 6970555

When rounded, because thats what we do, the only two distance that round correctly are 900 and 1K..

Anyway that why the Mike was saying use of the BC number for your mill wind -- ie a .618 at normal 2850ish is should be a 6mph gun, as a .515g1 175 30 cal running 2650, would be a 5mph gun. AS you mentioned when we run 3050+ it acts like a higher BC just as if we we running like molasses the other way.

The idea is super simplistic take the BC at nominal caliber speeds and use it as your mil wind speed.

Not hear to argue, just try to bring clarity to the concept.

 

[bornhunter04]

No average elevation is about 800ft. DA is usually 1500-2000. I did round up a bit to see if it would make sense for remembering 500 is a .54 and 600 is actually a .56 but my app lines back up @ 800 with a .8 and 1.08 @ 1k.

 

[Deleted member 113831]

No average elevation is about 800ft. DA is usually 1500-2000. I did round up a bit to see if it would make sense for remembering 500 is a .54 and 600 is actually a .56 but my app lines back up @ 800 with a .8 and 1.08 @ 1k.

When I run the numbers you gave me, you should be seeing 1.24mils at 1000 with a 6mph wind.

I don't speak in DA, but that bullet, at that speed, runs 1.02 mils at 25.0 Hg. One of us seems to have our inputs wrong.

But even with that drastic of a change, you see how close it is. Basically it's a "5" or a "6".

 

[bornhunter04]

When I run the numbers you gave me, you should be seeing 1.24mils at 1000 with a 6mph wind.

I don't speak in DA, but that bullet, at that speed, runs 1.02 mils at 25.0 Hg. One of us seems to have our inputs wrong.

Probably me..... What I've got is 800ft, 29.07 hg, 50% humidity, 59*f. I'm using the Hornady app. 5mph in AB gives me 1.0 @ 1k, .7 @ 800, .5 @ 600, and .4 @ 500. 6mph gives me 1.2 @ 1k, .9@800, .6@600

 

[Deleted member 113831]

Probably me..... What I've got is 800ft, 29.07 hg, 50% humidity, 59*f. I'm using the Hornady app. 5mph in AB gives me 1.0 @ 1k, .7 @ 800, .5 @ 600, and .4 @ 500. 6mph gives me 1.2 @ 1k, .9@800, .6@600

I just ran it in 4DOF and got 1.31mils (6mph) at 1000 yards. Maybe you have the wrong bullet loaded? Something is definitely amiss. Anyway, you seem to have the concept.

 

[Diver160651]

When I run the numbers you gave me, you should be seeing 1.24mils at 1000 with a 6mph wind.

I don't speak in DA, but that bullet, at that speed, runs 1.02 mils at 25.0 Hg. One of us seems to have our inputs wrong.

But even with that drastic of a change, you see how close it is. Basically it's a "5" or a "6".

You are correct. The 130 eld in a 6mph wind @ hs me should be +.2 at 1000..

Not from a calculator but from thousands of 6.5 130s

He has something wrong even in the early stuff.

 

[bornhunter04]

Thanks guys I'll figure out where I've got the wrong input and report back.

 

[Diver160651]

^ lol I am not using a solver - just Siri

I am with clients all day—- Skoo will get to the bottom of it but it would not surprise me if you had bad baro instead of station.. or a zero offset

 

[Hondo64d]

John,

Maybe check your solver again.. I am not saying your logic is not solid, but run numbers where the majority of your shooting takes place and real temps.. then at the longer range add or subtract

Wind does't work exactly as drastically as drag.. as an example at 800 yards with my load - to go between a 5mph and 6mph gun by temp alone, with a .8 drift; I'd need the them to be 5° F to use 5mph and can still use 6mph .8 hold @ 120°F. Thats 115° temp swing -- Not many places I'd realistically, see those kinds of swings..

So rather than try to manage it that way, for me I might modify the yardage points on were it turns for the temp difference’s..

I use ballistic AE. Had a cold snap the other day and my DA was -90’. During the summer it’s typically a 4500’ DA. 5mph wind bracket in the winter and 6mph in the summer. I’m currently shooting 130gr AR Hybrids at 2892fps. During the summer, a 7mph wind gives me .1 mil per hundred out to 600 yards. At 800 it changes to a 6mph wind out to 1000 yards. I just use 6mph and .1 per hundred out to 1k. If I’m .05 mils off at 700, I don’t care. That’s only 1.26”. I only wish I could hold that close. During a cold winter day here a 5mph wind will give me 1 mil of drift at 1000. I use .1 mil per hundred out to 1k. If I’m shooting closer and am off an inch or so I don’t care.

John

 

[MarinePMI]

 

[Kane0519]

A month later & that gif still makes me laugh!

 

[surprise]

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