Advanced Marksmanship Mirage. How much effect does it have?

[Ksracer]

How much can mirage affect your poi? Let's say there is very little wind and you have a medium boiling mirage. I know if you hold center plate at 700yds, you are going to impact low, but how much?

Will turning the scope down in magnification bring the impact back up?

I saw an article that said 1.5moa, but it didn't reference a yardage. Will it be 1.5moa at any yardage, or will it be 3moa at twice the range?

 

[...]

you treat mirage a lot like you treat wind.....except its a lot harder to call.

ive personally seen a heavy boil throw shooters off by a few inches at 100yds.

if you dont adjust for mirrage, ide guess a meduim boil could throw you off by nearly a foot at 700 yds.

the thing about mirrage is, its altering how the target appears to your eye, so its really caliber and yardage independent.....it works on the same principal as refraction ( ie, seeing a straw bend when you put it in water)


and honestly, i dont know of any way to quantify it for you....its not like you can "measure it"....i just kind of SWAG it and go from experience....but if anyone does know of a way to quantify it, ide love to hear it, haha

 

[Ksracer]

you treat mirage a lot like you treat wind.....except its a lot harder to call.

ive personally seen a heavy boil throw shooters off by a few inches at 100yds.

if you dont adjust for mirrage, ide guess a meduim boil could throw you off by nearly a foot at 700 yds.

the thing about mirrage is, its altering how the target appears to your eye, so its really caliber and yardage independent.....it works on the same principal as refraction ( ie, seeing a straw bend when you put it in water)


and honestly, i dont know of any way to quantify it for you....its not like you can "measure it"....i just kind of SWAG it and go from experience....but if anyone does know of a way to quantify it, ide love to hear it, haha

Nearly a foot at 700 yds is pretty significant. Last time I was out, I had a 15mph wind to deal with, but my elevation was on compared to the Applied Ballistics kestrel. Today the winds were better, but I had the mirage. Impacts were about .2 or.3mil low from 300-1000yds.

 

[morganlamprecht]

remove the winds from your kestrel for elevation and it'll probably help

 

[Ksracer]

remove the winds from your kestrel for elevation and it'll probably help

Interesting. The winds stiff winds the previous time were from 10 o'clock, so I beleive the kestrel would have added elevation to compensate for aerodynamic jump. Are you saying it overly compensates and I would have been low last time out without it falsely factored in also?

 

[morganlamprecht]

Interesting. The winds stiff winds the previous time were from 10 o'clock, so I beleive the kestrel would have added elevation to compensate for aerodynamic jump. Are you saying it overly compensates and I would have been low last time out without it falsely factored in also?

im not really in the position to argue with Litz about the formulas and numbers or anything...but after seeing myself and a couple buddies always dealing with a few tenths high/low in varying wind directions using kestrels, i quit using the wind function until after getting my elevation in Jan of this year...and all of our little elevation variances went away...it even required less truing on new loads...before i would always have to tweak velocity (+/- 25-40 fps) and BC to get things to line up...since taking the wind out, ive been able to leave the magnetospeed velocity alone and only tweak BC slightly for targets past 800 yds

http://www.scout.com/military/sniper...m-magnetospeed

heres a link to my thread asking about it on the scout site...seems most everyone had similar experience to mine

basically, one day at the range...i put all the same (trued/proven over a year of shooting) info into 3 different ballistic calcs...JBM, Ballistic AE, and AB Kestrel...kestrel is the only one that factors in AJ, and it was the only one that didnt get me on target

 

[...]

Here is a good article on mirage

http://southtexasshooting.org/multim...xt/mirage.html

https://loadoutroom.com/12938/snipers-mirage-tip-week/

But if you were hitting low, i dont know that that is dut to the optical displacement of the target....because generally mirage will cause your target to look higher than it actually is, causing you to hit high

 

[Ksracer]

im not really in the position to argue with Litz about the formulas and numbers or anything...but after seeing myself and a couple buddies always dealing with a few tenths high/low in varying wind directions using kestrels, i quit using the wind function until after getting my elevation in Jan of this year...and all of our little elevation variances went away...it even required less truing on new loads...before i would always have to tweak velocity (+/- 25-40 fps) and BC to get things to line up...since taking the wind out, ive been able to leave the magnetospeed velocity alone and only tweak BC slightly for targets past 800 yds

http://www.scout.com/military/sniper...m-magnetospeed

heres a link to my thread asking about it on the scout site...seems most everyone had similar experience to mine

basically, one day at the range...i put all the same (trued/proven over a year of shooting) info into 3 different ballistic calcs...JBM, Ballistic AE, and AB Kestrel...kestrel is the only one that factors in AJ, and it was the only one that didnt get me on target

I had a 9mph wind at 10 o'clock this morning. I confirmed zero, and left wind speeds at 0 in the kestrel. Elevation was spot on until 1200yds.

The true test will be to see if I impact high when they switch to the other direction.

 

[morganlamprecht]

im interested to see how it works out for u

 

[Ksracer]

Here is a good article on mirage

http://southtexasshooting.org/multim...xt/mirage.html

https://loadoutroom.com/12938/snipers-mirage-tip-week/

But if you were hitting low, i dont know that that is dut to the optical displacement of the target....because generally mirage will cause your target to look higher than it actually is, causing you to hit high

Ya, good point, I had that just backwards.

 

[damoncali]

Very little in my experience. No more than a click or two.

 

[TonyTheTiger]

Good info here. I was shooting a 2" plate at 100yds today and either missing low or edge hitting the bottom. Zero was dead nuts 4 days ago with conditions around 70 degrees, low humidity, late afternoon, zero mirage. Today it's around 75 degrees, very sunny and humid and my sight picture looks like I'm viewing through a fish bowl. I shot 4 groups on paper to check zero again, the centers of 3 groups where exactly .25 mils low and .1 mil left. The 4th group started the same but the wind picked up mid group and the mirage cleared up a bit and the remaining two shots where on POA. Now I'm resisting the urge to reset the turrets, I'll check zero next time the mirage is low/gone and see if everything is back to normal.

 

[TonyTheTiger]

Update: shot again today in zero mirage conditions and POI/POA was on the money. I'm going to shoot the next sunny day I can to see how consistent the mirage effect is. I didn't mention it above but all the groups where 5 shots and .5-.7 MOA which is average accuracy for this particular gas gun, so I'm confident the low groups weren't caused by lack of skill. My oldest son also shot (he averages 1.5 MOA) and his group centers where also low in heavy mirage conditions.

 

[Killswitch Engage]

im not really in the position to argue with Litz about the formulas and numbers or anything...but after seeing myself and a couple buddies always dealing with a few tenths high/low in varying wind directions using kestrels, i quit using the wind function until after getting my elevation in Jan of this year...and all of our little elevation variances went away...it even required less truing on new loads...before i would always have to tweak velocity (+/- 25-40 fps) and BC to get things to line up...since taking the wind out, ive been able to leave the magnetospeed velocity alone and only tweak BC slightly for targets past 800 yds

http://www.scout.com/military/sniper...m-magnetospeed

heres a link to my thread asking about it on the scout site...seems most everyone had similar experience to mine

basically, one day at the range...i put all the same (trued/proven over a year of shooting) info into 3 different ballistic calcs...JBM, Ballistic AE, and AB Kestrel...kestrel is the only one that factors in AJ, and it was the only one that didnt get me on target

^^^^^ this 100%

 

[Ksracer]

Since this is getting some traffic again. I'll update it. I eliminated mirage by screwing a rail to a sturdy bench, and zeroing a scope on an object and then observing it during different light conditions. It was not causing the issues I experienced. One of my issues was an anti-cant level I had just installed, that I somehow did not get parallel with the reticle, and while using windage holds, I was forcing myself to cant my rifle. Next issue was the kestrel. I started leaving the Wind1 speed at zero, and that helped also.

 

[Ksracer]

Sorry about that. Yes, I was confusing you and Tony. Quite embarrassing. My social media skills are still at a novice level. I deleted the post because it made no sense in that context. I am glad you found the solution to your problem.

I have erased mine also. No harm, no foul. The amount of information on social media can be an overload at times.
Thanks for your information, I had never considered the strength of the sunlight, other than the mirage that comes with it, as a factor before. I will pay attention for it in the future.

 

[Bigwheels]

Check out this pic. Was verifying zero on my 300WM. I was in the shade prone & the target was in the shade. But 1/2 the distance was in the sun. The stacked group in the box was 1/4" left & low of poa. (center of the box) Wind was right to left between 2-5 mph. Those were fired when the mirage was lazy. The group farther low & left was fired when the mirage was running strong. I must say that I was pretty surprised at the difference but I recognized it right away.

 

[Ksracer]

Check out this pic. Was verifying zero on my 300WM. I was in the shade prone & the target was in the shade. But 1/2 the distance was in the sun. The stacked group in the box was 1/4" left & low of poa. (center of the box) Wind was right to left between 2-5 mph. Those were fired when the mirage was lazy. The group farther low & left was fired when the mirage was running strong. I must say that I was pretty surprised at the difference but I recognized it right away.

That's a 100yd target, I'm assuming? That's a crazy amount of shift, I've never ran across that much before at close range, but I don't shoot at 100 alot either. I will say that at the last match, I missed some 1k yrd targets .4mil high under some horrible mirage conditions. It may be time I do some more testing on this subject.

 

[Darkside-Six]

I typically see anywhere from .2 to .4 low when the mirage is heavier. There are ways to try and adjust for it by lowering the power or parallax but when it's heavy it's heavy. Last time I shot over distance with a good mirage I was holding .2 over and getting solid impacts. There is not set formula, like someone said above just a SWAG.


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[Fursniper]

I typically see anywhere from .2 to .4 low when the mirage is heavier. There are ways to try and adjust for it by lowering the power or parallax but when it's heavy it's heavy. Last time I shot over distance with a good mirage I was holding .2 over and getting solid impacts. There is not set formula, like someone said above just a SWAG.


Sent from my iPhone using Tapatalk

You see .2 to .4 low with heavy mirage AT WHAT DISTANCE?

 

[mrbig]

from all my bouts with a boil I always hit high,,,I was shooting at a 10 inch plate at 1,030 yrds the other day with a 6.5x47,,my 28.5 moa elevation was dead on with a 2 moa wind right to left,,I was banging it pretty good ,shots centered and hit 5-6 in a row,,,the wind died and the mirage was boiling and I could barely see the plate and cranked down to 15x and the next round hit just over 1 moa high and 2 moa right I had dialed in ,,the next 10 shots I hit ever shot but one holding dead on when I had the wind and holding 1 minute low and 2 moa left,,

I was always told to never shoot a boil but sometimes stuff needs shot and you cant wait for perfect conditions

 

[Bigwheels]

Unfortunately over the years I have seen high & low poi in mirage. I wonder if there is something with the humidity &/or temp or maybe even up vs down shot angle that determines whether it's high or low?
Mostly I tend to see high impact at longer ranges but I'm also shooting across valleys when shooting that far. No long range flat ground in these parts.

 

[Bigwheels]

Anyone have a link to a good tutorial on the subject?

 

[Ksracer]

Will magnification effect it? Or is it present even if you can't see it? I'm referring to mirage
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[Gunfighter14e2]

Anyone have a link to a good tutorial on the subject?

There are many out there on iron sights shadowing, vs light angle vs target direction. The same with less effect holds true with glass and the power your using. My range days are either right at day break or just before dark to avoid public range people. On 10X @ 200yds I get 3/8-1/2moa of wind-age every time. Depending light from either if those to high noon on a bright day, it's almost a 3/8moa up change.
Light up-- site up
Light down--sight down
Sun on right --- dial left
Sun on left dial right
It's all about shadowing.
For fun set two identical targets, one in bright sunlight at a tree line, another at the same range in complete shadow in the wood line.
Experimentation results, trump internet lore.

 

[Bigwheels]

I spent an hour or so last night reading on the subject. In high power the lights up, sights up requires a setting that will cause a higher poi.
But I also found many writers calling for a lower poi on the target. I have seen both but some could easily have been due to updrafts in the mountains.
I haven't been able to find anything that would give a rule of thumb to determine which way to go. I'll try to look for something scientific on light refraction & see if I can find it there.

 

[Bigwheels]

I found a book that was interesting on the subject. It was written by a guy in 1850+/-. It is kinda hard to follow since it's written on an older form of English but it was interesting nonetheless.
https://books.google.com/books?id=CyACAAAAYAAJ
I was able to read some of it without getting the whole book by googling (not Bing) atmospheric refraction in shooting.
It turned up on PG2 Its called 'How to become an expert shot.' He writes about some of his experiences shooting long range with black powder and the fact that he noticed that when it was hot and sunny his shots would always hit high. Was a good read. Pg 14 is where he begins this subject.

 

[TheGerman]

Remember, the higher over 10-12x you go, the more the mirage will be apparent. Sometimes it pays to use fundamentals over available magnification.

 

[Gunfighter14e2]

I spent an hour or so last night reading on the subject. In high power the lights up, sights up requires a setting that will cause a higher poi.
But I also found many writers calling for a lower poi on the target. I have seen both but some could easily have been due to updrafts in the mountains.
I haven't been able to find anything that would give a rule of thumb to determine which way to go. I'll try to look for something scientific on light refraction & see if I can find it there.

Target lighting an target color effect some people differently. Try this, set 2-4 minute sized targets all at the same range at 600yds or more. Paint them in different colors, then ret range each one. Then set them at a 45* angle to the sun then re-range. Then angle them into the sun an range again, recording everything in a data book. Then on a cloudy day re-do the test again an note the differences. Take a bright orange target an set it next to a flat black target of the same size, an ret range them both. You will see a pattern.
Most don't know, but color correction error can make you miss a smaller target real quick.

 

[Greg Langelius *]

"Light's up, sights up..." from Highpower Comp, Benchrest, etc. The issue may not be mirage; it may be a product of light intensity.

Also, a boil indicates hotter air, which is less dense, hence less air resistance (and time of flight), hence less drop.

The bullet is dropping from the instant is it no longer supported within the barrel. How far it drops is a direct consequence of flight time. Shorter flight time, shorter drop, and vice-versa.

These two examples demonstrate opposite consequences, which fuels the confusion, but both are valid explanations for two different causes.

The issue with mirage is at least as much a matter of having a distorted image to aim at as it about how the mirage discloses localized crosswind, up/downdraft air forces pushing the projectile off the ideal path. The mirage forces the shooter to aim to a place that is not actually in line with a true straight line to the aiming point, so of course the shot goes off the intended aim. Two inputs, two results, neither of which is necessarily acting the same way.

There are a lot things happening within the air mass through which the bullet passes. They all add/contribute to uncertainty. If we imagine shooting through a vacuum, those influences will disappear, and predictability increases.

The average drop at 1000yd is somewhere around 30MOA or roughly 300 inches. Less at altitude. That's still only 1/2 of one degree. The effects of air disturbances and optical distortions are actually very small, but we can see that it doesn't take much to cause a deflection of 1MOA (10 inches, 1/60th of one degree).

Seen in such a context, being able to shoot to 1-2MOA is a mechanical miracle, and Ma Nature doesn't really like miracles. As we bang up against the far limits of the mechanics within a capricious environment, we are going to have to confront a reality that those limits do exist, and always will. Even a laser beam of parallel light will deflect (expand, etc.) due to refractive variances within the intervening air mass.

Be happy with such miracles as actually exist.

Greg

 

[Darkside-Six]

You see .2 to .4 low with heavy mirage AT WHAT DISTANCE?

800y and out.

 

[Fursniper]

800y and out.

Interesting & thanks. Heavy mirage usually has me shooting high out past 1k. Obviously, there is no uniform pattern to this....

 

[jsthntn247]

I shoot monthly fclass matches at 600 and 1000. Heavy mirage will push you low into the 9 ring. That equates to about 3" at 600 and 5" at 1k depending on how heavy the boil is.