.22LR Wind Formula

[rybe390]

Posted over in external ballistics but thought it could fit here too. Mods if this is a no-no, let me know.

So, as lots of us have been discussing/listening to wind talk here, specifically about the BC method for wind, I have been giving some thought specifically to .22LR wind.

And….I think we have a mil based system that is equally as fast, but for .22LR!

So, it’s super similar to the BC method. We’re using wind speed and range to determine our holds.

We basically assign the gun a “1mph wind bracket”, and call it a 1mph gun. For distance, we’re going more granular than 100,200, etc. We’re going 80,90,100,110, etc. Wind gets a decimal after the first number, and range after the second number.

Wind: 0.7 for 7mph, 1.2 for 12 mph, and 1.0 for 10mph, just to give examples
Distance: 0.75 for 75 yards, 1.00 for 100 yards, 1.50 for 150 yards, again, examples. 200 is 2.00, 350 is 3.50.

Essentially, you take your two numbers, multiply them, and you get your wind hold. Blam.

Examples:
10 mph at 100 yards, 1 mil hold. 1.00 x 1.0 = 1
15mph at 100 yards, 1.5 mil hold. 1.00 x 1.5 = 1.5
5 mph at 150 yards, .75 mil hold. 1.50 x 0.5 = 0.75
10 mph at 200 yards, 2 mil hold. 2.00 x 1.0 = 2.0

Drop chart to back it up. 10mph full value. Close enough for government work, or precision rifle shooters. Whatever you're into.

Drop Chart

I saw this trend when running a 10mph wind out to 300 yards in AB. It’s pretty dead on, +- 0.1 mil. Running 1060 fps at 4,000ft DA for my example. Confirmed taking out to 400 last weekend. Makes life a hell of a lot easier.

So, debate away, I’m sure I’ll get flamed a bit for this, but wanted to show you all.

 

[Hookturnr]

This looks close to what I've been getting, I'll have to try it out!

 

[Deleted member 113831]

I applaud your zeal. That is a very different way of explaining an old formula.

What you have discovered (re-discovered?) is the old Marine Corps / Army formula of:

Range/100 x wind (in mph) / 10 (constant) = Hold in MOA (but you are working it in MILS)


To stay true to the MPH method:
1) Take a distance like 200 yards and divide it by 10 increments. So, 20 yard increments.
2) Find a wind that gives you 1 MIL drift at 200 yards (should be somewhere around 7 mph).
3) This wind gives you .1 MIL drift per 20 yards.
4) You have a 7 mph gun out to 200 yards.

 

[rybe390]

I applaud your zeal. That is a very different way of explaining an old formula.

What you have discovered (re-discovered?) is the old Marine Corps / Army formula of:

Range/100 x wind (in mph) / 10 (constant) = Hold in MILS


To stay true to the MPH method:
1) Take a distance like 200 yards and divide it by 10 increments. So, 20 yard increments.
2) Find a wind that gives you 1 MIL drift at 200 yards (should be somewhere around 7 mph).
3) This wind gives you .1 MIL drift per 20 yards.
4) You have a 7 mph gun out to 200 yards.

I guess it's pretty similar, and instead of dividing, you quite literally just slide a decimal place on both numbers, and skip the constant as it is 1.

It just excites me that you can essentially use the wind bracket BC method at 1 mph, and use the same yardage guidelines. 10mph at 100 yard = 1 mil is stupid simple. 5 mph at 100 is .5.

I'm not a fan of the second example as it's honestly a bit harder to wrap my head around quickly. This BC method has changed the game for me and honestly makes it almost mathless on the fly, and discovering? the .22lr application of it has been a light bulb moment for me.

 

[Deleted member 113831]

I guess it's pretty similar, and instead of dividing, you quite literally just slide a decimal place on both numbers, and skip the constant as it is 1.

It just excites me that you can essentially use the wind bracket BC method at 1 mph, and use the same yardage guidelines. 10mph at 100 yard = 1 mil is stupid simple. 5 mph at 100 is .5.

I'm not a fan of the second example as it's honestly a bit harder to wrap my head around quickly. This BC method has changed the game for me and honestly makes it almost mathless on the fly, and discovering? the .22lr application of it has been a light bulb moment for me.

The beauty of the BC / MIL / MPH method (whichever is your favorite title) is that it can be adapted.
You can figure it anyway you wish.

You can set it up so that your distance is an even number which is then divided into some multiple of 10....

Or.... you can set it up so that your bullets drifts say, .1 MILS per 25 yards, or 20 yards, or 30 yards...,whatever you wish.

No matter the division, the resulting wind is the MPH for your gun.

 

[captainemil]

what about head and tail winds? ran across a problem yesterday , just 1 example, at 175yds 17.5moa with no wind ,with a 12mph wind 15.50moa thats 2 moa difference. that was a tail wind.