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Advanced Marksmanship How do you calculate wind correction without a ballistic calculator?

goodgorilla

Sergeant
Full Member
Minuteman
Nov 16, 2013
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Lecanto, FL
I've been reading a book called Reading wind for the rifle shooter, so I believe that I understand the basics on how wind correction is suppose to be done. However, so far in the book it doesn't address ballistic coefficient, bullet velocity, or basically anything about a custom load. I'm most interested in basic calculation and nothing about winds blowing in different directions or changing winds. I would appreciate any help here.
 
have you looked at a ballistic app yet for your smart phone? most, if not all of them will have areas for you to put all this info in and it calculates it for you.
 
have you looked at a ballistic app yet for your smart phone? most, if not all of them will have areas for you to put all this info in and it calculates it for you.
I have not looked at any ballistic calculators yet even though I do own a kestrel with applied ballistics. I'm not using the device yet because my first rifle isn't completed. I understand that the ballistic calculator is really accurate. What got me thinking about doing it manually is because I doubt the ballistic calculator will work right if the winds are changing directions, if there are opposite winds through out the bullet flight path, or if the wind speeds are changing. I also understand that the wind closest to the shooter affects the bullet the most, and my lack of experience doesn't tell me if the downrange wind isn't that important.
 
Trying to do it manually is tricky because the wind is never constant. It is ever changing. I use an app called "Ballistic AE" for the iPhone. It is one of the more popular ballistic apps out there and works great. In it, you can input multiple wind directions to give you an adjustment. If the wind is left to right at the muzzle but right to left mid range or at the target it lets you put that info in to account for it.

No need to over complicate things. Just get out and shoot, and record your shots. That is what will help you the best.


Sent from my iPhone using Tapatalk
 
I try to do it in my head (using a fairly basic formula) THEN check my work against a ballistic calculator. I don't want to rely solely on an electronic gadget.
 
Go to JBM Online and put in your bullet specifics... it's free.

Print the sheet and laminate it ...

problem solved, if you are trying to do math in the field you're not only wrong but stupid wrong. Prior Proper Planning Prevents a Piss Poor Performance

have a plan before you show up.
 
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Go to JBM Online and put in your bullet specifics... it's free.

Print the sheet and laminate it ...

problem solved, if you are trying to do math in the field you're not only wrong but stupid wrong. Prior Proper Planning Prevents a Piss Poor Performance

have a plan before you show up.

Probably worthy of the stupid questions, but how do you determine the direction at your position? Drop some sand? I also saw that you can hook up the kestrel on something that can get the wind direction, but that thing looks kind of clunky.
 
Ya that is a pretty stupid question.

I would seriously consider taking a class, the questions you ask and the direction you're taking things on your own is not doing you any favors. It's possible to fill your bucket with nothing but bad habits and faulty understandings that will do much more harm than good.

Find a reputable instructor and save yourself a lot of time.

Wind direction is based the clock system or degrees of a circle. The direction of the barrel is 12, right is 3, left is 9, you're not really up to fine variations at this point. Look up a Wind Rose if you really want that degree of finesse. If you're really and truly confused on the direction tie a 6" piece of yarn to the barrel.
 
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Ya that is a pretty stupid question.

I would seriously consider taking a class, the questions you ask and the direction you're taking things on your own is not doing you any favors. It's possible to fill your bucket with nothing but bad habits and faulty understandings that will do much more harm than good.

Find a reputable instructor and save yourself a lot of time.

Wind direction is based the clock system or degrees of a circle. The direction of the barrel is 12, right is 3, left is 9, you're not really up to fine variations at this point. Look up a Wind Rose if you really want that degree of finesse. If you're really and truly confused on the direction tie a 6" piece of yarn to the barrel.

I know what wind direction is and how to use it, come on. I was just asking how do you go from. I feel this wind on my face to, the wind is coming at me at 11:30. You use a piece of yarn for that? That could work.
 
Disclaimer: I retired from the Army many, many years ago and am finding in my older age I'm forgetting a lot. just now getting back into shooting and have a GAP on order :)

That being said, here's how I remember it:

1st. The wind down range effects your shot more than the wind closest to the shooter. Theory being that the bullet in your immediate area is moving faster than it is down range. Therefore the wind down range has more time to do its damage.

2nd. What I was taught back in the stone age was to take a reading in my immediate area. Take a reading down range (mirage, debris etc). Average two and you'll end up pretty close. example: 5mph miles at shooter / 10mph down range I'd figure about 7.5 mph wind.
 
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Here's a formula: distance to target in yards divided by 100, multiplied by wind velocity valued as half or full value by wind clock, divided by constant, equals MOA of drift. Example, 600 yard target, 10 mph wind seen as having a half value, shooting .223, which uses a constant of 10, would take 600 divided by 100 equals 6 times 5 (half value of the 10 mph wind) equals 30 divided by 10 equals 3 MOA of drift or 18 inches of favor.

I take my wind reading at mid range which appears to be a good average for wind from shooter's position to target. The constant of 10 is not exact but allows for fast on the gun math for a good quick hit. This constant can be used for .308 and other high velocity bullets with b.c. in the .350 to .550 range. Considering that nothing about wind is exact for more than an instant in time, the formula I use works well for fleeting moments where time constraints do not allow for much figuring or time looking over a chart. Remember, for a good hit other calculations or appraisals must be made too, like distance to target, holdover, and slope, so being able to hastily counter for wind is useful.
 
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I know what wind direction is and how to use it, come on. I was just asking how do you go from. I feel this wind on my face to, the wind is coming at me at 11:30. You use a piece of yarn for that? That could work.

I will often just pluck a tuff of grass and toss it. This means of direction detection is useful in HP competition, 300 yard rapid fire from standing to prone, when conditions do not allow me to get back on the spotting scope to view mirage.
 
When not shooting or practicing for a match, as SS says tossing a tuff of grass or dirt works.

In competition or other places where I use a spotting scope I have a ribbon tied to the top of my scope stand that instantly tells me the direction of wind.

IMG_01261.JPG
 
[MENTION=16991]chase1[/MENTION]

completely wrong on both counts, I suggest editing your post as it's incorrect

Had to go dig out old gear.

So wind Yds x Wind mph / constant ( have 13 with *12 written next to it) I stand corrected.

In terms of which has more effect, i stand by it. On a 1000yd range, your bullet is going to have "more time" in the second half of the range, thus more time for wind to effect.
 
In terms of which has more effect, i stand by it. On a 1000yd range, your bullet is going to have "more time" in the second half of the range, thus more time for wind to effect.

You might get a bit lonely standing there all by yourself.
 
You might get a bit lonely standing there all by yourself.

Again checked my books from Benning its what I have written in several places. So I googled it and found I'm not that alone.
https://www.youtube.com/watch?v=p026Y0WUy6Q

But hey, to each his own. Back in the day I've seen a lot of great shooters each with their own little way of doing things. Here in Texas I see old timers take down hogs at amazing distances. No Kestrell, No phone apps, no data books...just years of shooting
 
Wind deflection is not purely lateral. If it were, then you'd be correct. But every competetive long range shooter I know understands that deflection also has an angular component, which is why a bullet that is deflected earlier in its flight will be deflected more by the time it reaches the target than a bullet deflected nearer the target. While lateral deflection can counteract angular deflection in some unusual circumstances, those circumstances are not the norm.

Sniper manuals have been behind the times since their beginnings. Most are fraught with errors. The worst I've seen had wind rosettes that said the numbers shown were numbers of half minute clicks, when they should have been full minutes! Most contain the age old error that 45-degree winds are "half value" winds, just like the guy in that video perpetuates. It's too bad that while he used trigonometry beautifully in his angle shooting video, he abandoned it in this wind shooting video. I was elated to finally see correct values for angular winds given in a 2004 Marine Corps Scout/Sniper Data Book. It's about time!
 
BC Based Wind Calculation Method

The BC method simply states that if a 308 has the BC of .4xx so you use the first number in the BC as the wind or per 4 MPH. If you use a bullet with a different BC that first number is the BC value you use for the wind speed. So a 5.56 would use 3 MPH based off the .3xx BC for the bullet. If your 308 has a .496 bullet just round up to .5 or per 5 mph.

100 = .1 mil per 4 mph
200 = .2 mil
300 = .3 mil
400 = .4 mil
500 = .5 mil

After 500 yards the velocity is changing you so have to adjust the values to account for this. It jumps up by .1 mils here.
The numbers continue this way.

600 = .7 mil per 4 mph
700 = .8 mil
800 = .9 mil
900 = 1 mil
100 - 1.1 mil

Rather simple you just change the MPH value for .1 mils based off the bullet’s BC. It’s not perfect, but it’s fast and easier to remember than doing a long hand math formula in the field.
 
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Wind deflection is not purely lateral. If it were, then you'd be correct. But every competetive long range shooter I know understands that deflection also has an angular component, which is why a bullet that is deflected earlier in its flight will be deflected more by the time it reaches the target than a bullet deflected nearer the target. While lateral deflection can counteract angular deflection in some unusual circumstances, those circumstances are not the norm.

Sniper manuals have been behind the times since their beginnings. Most are fraught with errors. The worst I've seen had wind rosettes that said the numbers shown were numbers of half minute clicks, when they should have been full minutes! Most contain the age old error that 45-degree winds are "half value" winds, just like the guy in that video perpetuates. It's too bad that while he used trigonometry beautifully in his angle shooting video, he abandoned it in this wind shooting video. I was elated to finally see correct values for angular winds given in a 2004 Marine Corps Scout/Sniper Data Book. It's about time!

I am more concerned about error from inconsistent recoil resistance than from wind, since taking a reading of mirage at mid range when possible will provide a good idea of what counter is necessary for a good hit. And, although getting the wind right is important, as it has the most effect on ballistic trajectories, it is not difficult to master just by getting out and doing it and making a record of its effect in a data book. Far more difficult is to get a consistent position from shot to shot to realize the benefit of getting the wind right at LR. That's to say, a novice shooter who can't build a consistent position will have great difficulty discerning wind error from positional error unless the error is gross and persistent.
 
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Chase, just because others think the same thing does not mean you are right. In this case, you are wrong. The angular error induced by near winds continues to increase as the bullet moves downrange, since it has no way to return to its original track. This means a 100 yard band of 10 mph wind starting at the muzzle causes a greater net deflection at 1000 yards than a 100 yard band of 10 mph from 900 to 1000.

As with many things, in not so much what you know, it's what you know that just ain't so that causes a problem.
 
I am more concerned about error from inconsistent recoil resistance than from wind, since taking a reading of mirage at mid range when possible will provide a good idea of what counter is necessary for a good hit. And, although getting the wind right is important, as it has the most effect on ballistic trajectories, it is not difficult to master just by getting out and doing it and making a record of its effect in a data book. Far more difficult is to get a consistent position from shot to shot to realize the benefit of getting the wind right at LR. That's to say, a novice shooter who can't build a consistent position will have great difficulty discerning wind error from positional error unless the error is gross and persistent.

True, with practice both can be mastered. But hold is the same regardless of range, and once hold is mastered wind is much more important when shooting at long range. A shooter that can hold within a MOA will find himself out of luck if he cannot estimate wind at long range. A one mile per hour misjudgement at 700-1000 yards already has his shot outside of his hold.

Taking a reading at mid range may often be good enough for shooting paper on a flat range, since you can adjust off your call. I don't know what kind of shooting the op is doing, but when the first shot counts it helps alot to be able to read wind all along the bullet's path. A lot is going on between the shooter and the target at long range, especially if land contours are involved.

I completely agree with your last. The most important thing is to make a "perfect" shot, as only perfect shots will allow one to "know" what the effects of the wind were, speeding the learning curve.
 
True, with practice both can be mastered. But hold is the same regardless of range, and once hold is mastered wind is much more important when shooting at long range. A shooter that can hold within a MOA will find himself out of luck if he cannot estimate wind at long range. A one mile per hour misjudgement at 700-1000 yards already has his shot outside of his hold.

Taking a reading at mid range may often be good enough for shooting paper on a flat range, since you can adjust off your call. I don't know what kind of shooting the op is doing, but when the first shot counts it helps alot to be able to read wind all along the bullet's path. A lot is going on between the shooter and the target at long range, especially if land contours are involved.

I completely agree with your last. The most important thing is to make a "perfect" shot, as only perfect shots will allow one to "know" what the effects of the wind were, speeding the learning curve.

Just a thought prompted by your post, I think a novice shooter who wants to learn how to do it would be wise to record no-wind, beginning, and corrected zero for wind and weather conditions in a data book. Then, after the shooting exercise, the shooter can reconcile the result with facts from a ballistics program. This allows for an exacting translation from what wind feels and looks like into what to do about it. It also indicates the viability of technique and helps build confidence. An example might be that the shooter appraised wind at 12 mph when the wind was actually more like 8 mph. Would another approach or wind countering technique have produced a better result? The shooter only need compare the recorded solutions of all techniques yielding divergent results.
 
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Chase, just because others think the same thing does not mean you are right. In this case, you are wrong. The angular error induced by near winds continues to increase as the bullet moves downrange, since it has no way to return to its original track. This means a 100 yard band of 10 mph wind starting at the muzzle causes a greater net deflection at 1000 yards than a 100 yard band of 10 mph from 900 to 1000.

As with many things, in not so much what you know, it's what you know that just ain't so that causes a problem.


Hey Cory or anyone else in the know,

Do you guys know if ballistic calculators account for angular winds as well as lateral winds? Wind "all along" the bullets path including angular deflection near the muzzle?
 
[MENTION=16991]chase1[/MENTION]

still wrong, there are lots of guys who don't know but rather regurgitate old incorrect data. They basically copy and paste outdated information and guys like you take it as fact.

http://www.nvisti.com/wp-content/uploads/2014/06/NVDOC1403-Wind.pdf

here is a better graph to show you the percentages of wind effects.
 
Had to go dig out old gear.

So wind Yds x Wind mph / constant ( have 13 with *12 written next to it) I stand corrected.

In terms of which has more effect, i stand by it. On a 1000yd range, your bullet is going to have "more time" in the second half of the range, thus more time for wind to effect.

You couldn't be more wrong about the effects of wind on a bullet. Simple physics chap.
 
[MENTION=16991]chase1[/MENTION]

still wrong, there are lots of guys who don't know but rather regurgitate old incorrect data. They basically copy and paste outdated information and guys like you take it as fact.

http://www.nvisti.com/wp-content/uploads/2014/06/NVDOC1403-Wind.pdf

here is a better graph to show you the percentages of wind effects.

Well, I'm certainly not here to argue and I'm not one to absolutely insist I'm right (sometimes :).

As I said in my initial post its been over 20+ years since I left the Army and havent even thought about shooting until recently. That being said, it wasnt regurgitated information, it was directly from Army Instructors. I confirmed that with my old notes, then again with that video.

Now if what M40_A1 said is true about manuals being incorrect from the beginning, that would explain it and I stand corrected and apologize. Its beyond me why the DOD would have erroneous training manuals but then again, our Government seems to screw everything up.
 
[MENTION=16991]chase1[/MENTION]

still wrong, there are lots of guys who don't know but rather regurgitate old incorrect data. They basically copy and paste outdated information and guys like you take it as fact.

http://www.nvisti.com/wp-content/uploads/2014/06/NVDOC1403-Wind.pdf

here is a better graph to show you the percentages of wind effects.

Tried posting this earlier, but it didnt post for some reason.

Ok first, I'm certainly not here to argue nor am I one to absolutely insist I'm right (usually). I did state at the beginning of my first post that I retired from the Army over 20 years ago and it was very possible I had forgotten nearly everything I've ever learned. I havent even thought about shooting again until recently.

That being said, I do want to address your one comment. I didnt just read it from "some guy online who was regurgitating information on the internet". Its what the U.S. Army taught us (again validated by the Army veteran who's video I linked to) Now if what M40_A1 said is correct about manuals being faulty from the beginning, I suppose that would explain it. A little disheartening that the DOD would be teaching bad info, but nothing from our Gov. surprises me anymore.

So, if I was in fact wrong, taught by the Army wrong (possibly new science has proven that to be outdated) than I stand corrected and apologize for giving old, incorrect opinion.
 
There are a lot of errors in the manuals, they also say Higher Humidity makes the air more dense... that is wrong too. High Humidity means the air is "less dense", so less dense means bullets like high humidity. The fact air feels heavy in high humidity is a human response.

The information from 20+ years ago, even from the instructors does not mean much, they had no special training, especially back then.

Here is another news flash, Plaster just copied the data from the manuals and a lot of his data is wrong too. He repeated the same errors just like the video you posted. That guy is wrong too.
 
There are a lot of errors in the manuals, they also say Higher Humidity makes the air more dense... that is wrong too. High Humidity means the air is "less dense", so less dense means bullets like high humidity. The fact air feels heavy in high humidity is a human response.

The information from 20+ years ago, even from the instructors does not mean much, they had no special training, especially back then.

Here is another news flash, Plaster just copied the data from the manuals and a lot of his data is wrong too. He repeated the same errors just like the video you posted. That guy is wrong too.

Well....not sure what to say. As a young man in basic, it never crossed my mind to think our instructors were wrong - Assholes, but not wrong.

Can I assume they've come around and are training modern day troops more accurately?
 
That would be a rather bold assumption. Bad info still abounds, spoken as the gospel, even though it's demonstrably untrue. Sometimes it's hard to see it's wrong, since on the face it SOUNDS logical. Since so many people have no real way to test a lot of this, it persists as 'fact'. The humidity thing is an prime example. When I tell people in class that humid air is less dense, invariably I get a bunch of protests. Since it's such a small factor, it's hard for one to objectively test. On the other hand, I just ask them to look outside at the clouds and lets see if water vapor is more or less dense that dry air. If you need to look up, I'll go with less dense. Other things are not as simple to observe, doctrine is hard to change, and books hang around forever. I'm always amused by Plaster's diagram of mil reticles. Mil dots are 3/4 of a mil in diameter, HAH!
 
What a blunder the "3/4 mil" statement was. It wasn't just a typo either! He built a whole diagram breaking the reticle down, drawn to scale as though the dots were 3/4 mil in diamter, and even a description on how to use the fictitious reticle for ranging. I had to wonder if he had ever looked through a mil reticle scope. To be fair, though, he did correct this error in his updated and expanded edition.

The funny thing about the humidity error is that the 2004 edition of the SSIS finally abandoned the "humid air is heaver than dry air" BS. But to save face and not have to come out and say the opposite of what had been spouted for decades, they just printed "This will have little affect on the drag of the projectile even at ranges exceeding 800 yards." Hah! True enough! Much less embarrassing to put it that way!

So, yes, chase1, I do believe things are turning around slowly, and the information is becoming more accurate in the manuals and in training. It has to. More and more shooters are becoming interested in the long range game. Small arms are reaching out further and further. Trends that defy what was taught yesteryear can no longer go unnoticed and truth is becoming common knowledge.

Cory, JFYI, clouds are not water vapor. Water vapor is invisible. The clouds staying up in the sky makes an interesting point, but is not an accurate illustration for the humidity argument. As an aside, I have always wondered how hydrofluorocarbons can be partly responsible for global warming since they are heavier than air and somehow have to get all the way up into the atmosphere!
 
I guess this is where you can say "believe the bullet". Like these guys said, print and laminate a standard card with 5 and 10mph full value winds at all yardages you'll be shooting. The rest is just trigger time. A few people have really helped me reading the wind. All I can say it I NEVER hit a magical time in my learning where "I got it!" I'm slowly getting better. Just get out and shoot in the windiest crappiest weather(with a good spotter). And like an old timer taught me, watch your bullet trace! Notice how high your trajectory arc is. What's the wind doing up there??? Read up on mirage. Mother nature is trying to tell you what she's doing, you just got to learn her language.

Brian
 
Well, I sure have found out that a lot of what I learned years ago was incorrect (first edition of Ultimate Sniper) wow, explains why a few things didn't work...
At least I know where and what to study more of now, thanks for that.

Geez, what a bunch of wasted time, kinda like being taught 2+2=3.9
 
If you combo the Ultimate sniper book with the Ultimate sniper Choate stock, your golden! Sorry, guess I have to admit I have a choate on my 338. It really is a pretty solid stock. But the Ultimate Sniper still sounded good!

And yes...I took a sanding disk to the "ultimate sniper" on my choate stock and got rid of it!
 
Disclaimer: I retired from the Army many, many years ago and am finding in my older age I'm forgetting a lot. just now getting back into shooting and have a GAP on order :)

That being said, here's how I remember it:

1st. The wind down range effects your shot more than the wind closest to the shooter. Theory being that the bullet in your immediate area is moving faster than it is down range. Therefore the wind down range has more time to do its damage.

2nd. What I was taught back in the stone age was to take a reading in my immediate area. Take a reading down range (mirage, debris etc). Average two and you'll end up pretty close. example: 5mph miles at shooter / 10mph down range I'd figure about 7.5 mph wind.

You got it backwards. The wind closest to you has the most affect. The time of flight will be longer. A basic formula for calculating two different wind values is 2/3 for wind at your position, and 1/3 for wind at target.

(2*5) + (1*10) = 20/3 = 6.6

This is assuming full value wind coming from 3 or 9 O'Clock. If it is half or 80% value wind then you apply that to the 6.6.
 
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BC Based Wind Calculation Method

The BC method simply states that if a 308 has the BC of .4xx so you use the first number in the BC as the wind or per 4 MPH. If you use a bullet with a different BC that first number is the BC value you use for the wind speed. So a 5.56 would use 3 MPH based off the .3xx BC for the bullet. If your 308 has a .496 bullet just round up to .5 or per 5 mph.

100 = .1 mil per 4 mph
200 = .2 mil
300 = .3 mil
400 = .4 mil
500 = .5 mil

After 500 yards the velocity is changing you so have to adjust the values to account for this. It jumps up by .1 mils here.
The numbers continue this way.

600 = .7 mil per 4 mph
700 = .8 mil
800 = .9 mil
900 = 1 mil
100 - 1.1 mil

Rather simple you just change the MPH value for .1 mils based off the bullet’s BC. It’s not perfect, but it’s fast and easier to remember than doing a long hand math formula in the field.

This si genous if true.
 
Downzero

Well test is yourself and compare the BC wind method to JBM or any other ballistic program. Understand you need to use the G1 BC number and this would be for full value wind directions. It is not perfect but will get you within 0.1 or so compared to programs. Keep data and fine tune any wind calls and solutions for you personally, everyone calls wind different and every rifle system (aka rifle,scope and ammo) needs to be tested for solutions. Even numbers out of programs need to get adjusted for you, most likely reduced as programs over calculate wind IMHO.
 
More often than not the wind input is an experienced guess to get it to calculate a workable good response. A typical .308 needs to be estimated within 2 mph on a still 1.5 moa target past 400 meters to the point you need to be spot on at some point out there the further you go. It helps to know the margin of error on the wind call based on target size and distance. Thus, the upsurge in wind bucking calibers in demand.
 
You don't need BC, velocity etc...you need to get out and shoot. For some reason people don't want to work at anything anymore...they want spoon feeding. If you want to know what the wind drift/hold off is for your rifle, your load...get out and shoot in all conditions (TAKE NOTES)...record wind velocity for the first 50yrd, and if you're shooting LR (say past 600) you'll want to know your 300-600 wind as well. (how do you know about down range wind?- watch the grass, dust etc, mirage... With enough experience you'll know your adjustments for the given conditions.
 
Ballistic programs only give you a wind call for the input data, it will not give you adjustments for what the wind is doing down range. No one is going to have a perfect wind call in varying terrain, a flat range sure, but ranges where you shooting over hills or other terrain features, sure that ballistic program will probably give you an incorrect solution. You have to make that judgement call.

I've used TH1 Quick Wind the majority of my time shooting, it worked, can't complain. But recently I've spent my time creating a modified quick wind dope chart(s) for major density altitude changes that incorporates spin drift (works 60% of the time, all the time). Basically like quick wind but instead of 4mph (.308) as the constant it's 3mph for a left to right, and a 5mph for a right to left wind. It holds true out to 1000 yards, as far as I have had the chance to push it.