enviromental corrections-what do you use?

[RobertB]

I would like to know how people here correct for environmental changes in the field.

Whatever you use share it.

If you use elevation. barometric, humidity, temp or if you ignore it as well.

Topic is open for internal or external ballistics.

What is the distance you feel comfortable with? Wind aside

Basically, any thing you do to correct for a one shot can't miss type shot.


Thanks!

 

[RobertB]

does anyone correct? Or just come up sheets?

 

[MMERSS]

I could spend pages discussing the environment and long range shooting. Fortunately there are already some great books on this topic. I would suggest Applied Ballistics products. Buy a book or two, the environment is detailed to every aspect in Bryan's books.

BTW, don't be surprised if this thread is moved to another forum.

 

[RobertB]

Thanks. I study a lot about it and read a lot of Bryan litz info but I'm not trying to really learn it from this page. I am just wanting to know what people here do to correct. Or if they only feel comfortable out to say XXX yds I have been shooting lr seriously for about 6 years and studying envirometal changes hard for about 5. I'm no expert but I have seen a lot of people doing different things in those years. I have my ways of doing this that seems to work well but I might learn something from the guys doing it 10+ to 30+ years already. They might share one tool or method here that changes the way I look at the subject.

I wasn't real sure which forum it should go on but fiqured elr would be the right one as were discussing how to correct for shot that can be as long as you feel comfortable. If they move it my feelings wont be hurt lol.

 

[MMERSS]

Thanks. I study a lot about it and read a lot of Bryan litz info but I'm not trying to really learn it from this page. I am just wanting to know what people here do to correct. Or if they only feel comfortable out to say XXX yds I have been shooting lr seriously for about 6 years and studying envirometal changes hard for about 5. I'm no expert but I have seen a lot of people doing different things in those years. I have my ways of doing this that seems to work well but I might learn something from the guys doing it 10+ to 30+ years already. They might share one tool or method here that changes the way I look at the subject.

I wasn't real sure which forum it should go on but fiqured elr would be the right one as were discussing how to correct for shot that can be as long as you feel comfortable. If they move it my feelings wont be hurt lol.

Fair enough!

I primarily use two methods to determine air density and wind corrections; a computer and firing tables.

For both the computer and tables I have learned to love using a Density Altitude air density equivalent for corrections. The Kestrel 4500 will take your temperature, Baro, humidity, and altitude and convert this data to a Density Altitude equivalent. I have found it much easier to use a ballistics application that will take DA to determine the air density and apply this to the program. Only one input vs. many. Simple is smart.

I also print my tables for every 1000 ft change in Density Altitude. As I hunt thru the day, I take out the appropriate DA table for the current environmental conditions. For example, 0 ft DA, 1000 DA, 2000 DA etc. Look at your Kestrel every now and then. If it says 3220 DA, I pull out my 3000 table and place it in my back pocket. I will change as conditions change throughout the day. I have found every 1000 change is sufficient and rounding to the nearest 1000 will provide the elevation correction results you need without too much of an error.

Now it's the wind uncertainty that predominately limits maximum hunting range. On my tables I will color code the ranges with high, medium and low wind confidence with green, yellow and red highlights. These are my maximum ranges based on uncertainty to within a 1 MPH full value cross wind (green), 2 MPH uncertainty (yellow), and 3 MPH uncertainty (red). If uncertainty is more than 3 MPH I'm not shooting past 400 yards period and most likely even closer.

Primarily I will use a computer for ballistics solutions, then validate off my tables. Garbage in on a computer equals garbage out. Anyone can have sticky fingers now and then. The tables validate the firing solution.

Hope this helps and good shooting.

 

[RobertB]

Awesome, this is what I'm looking for right here.

My setup is exactly like yours in every way. I use kestrel for DA carry a small PDA for unusal shots but I have arranged DA cards myself on rite in rain paper for the majority of shots.

I have recently starting collecting all enviro dada in my log book to see if some things really show a pattern but I've had great luck with nothing but DA. I understand that is actually the same thing but I like to know every single aspect of it. On another form they were saying how DA is good when you need to be fast when not shooting very far, but I have had great luck with nothing but DA.

I just came from West Texas/New Mexico to New York and got to setup a shot to mimic a shot I made out west.

The yardage was 1330 verified by GPS and Vectronix LRF. Angle was the same wind was actually very similar as well. Only thing that was different was the place I was shooting.

My calculations were dead on out west with a 15.1 mil in elevation.
It was logged and witnessed by my spotter.

Then came to new York and the calculation put me at 18.4 mil.
Knew that that was a huge difference but had a mountain as a backdrop and knew I was safe to find out. Shot and hit within a click of it. A second round confirmed this.I knew that I had proven the method to myself. I had checked it many times but had never gotten to go where the weather was so different while I had the same rifle to really know it across the country. I believe this Hodgon powder to do very good with different temps so I think I'm adjusting external ballistics mostly.

I know wind is the biggest factor but I'm glad you told me how you do it.
I hope there will be other ways of doing it and just wanted to see some of em.
Technology really helps out when shooting little bullets a long ways.

Thanks for the response.

 

[MMERSS]

I have recently starting collecting all enviro dada in my log book to see if some things really show a pattern but I've had great luck with nothing but DA. I understand that is actually the same thing but I like to know every single aspect of it. On another form they were saying how DA is good when you need to be fast when not shooting very far, but I have had great luck with nothing but DA.

One caveat to consider when using DA and this can be important, Temperature Regression. If your powder requires temperature regression your program needs the powder temperature as an input. For most programs there is no way around entering a temperature if you select the DA option.

How do you get around this? Minimize temperature regression by zeroing your rifle in average temperatures most likely to be encountered during your hunting and record average MV. Zeroing in average hunting temperature serves two fold.

1) You are minimizing the powder temperature pressure differences which cause changes to your average muzzle velocity. If you are using less temperature sensitive powders and zero your rifle in average hunting temperatures this will eleviate this issue. Additionally to help with this issue, if it is significantly colder outside than your zero temperature you can place your ammo in a pocket close to your chest, drop your Kestrell in with that pocket and monitor the temperature. If the powder temperature is too cold or too hot simple move to a pocket closer or farther away from a body warm zone.

2) Harmonics. Don't you want to know how your rifle and ammo combo responds to specific conditions? At times my rifle POI and POA will change significant enough with a severe temp change to cause unnecessary errors at extended ranges.

 

[BrentM]

Wind (not just left to right but 3d) I shoot mountain terrain.
Absolute Barometric Pressure
Temp
Coriolus
spin drift
Humidity, to lesser extent.

** Wind. I adjust for elevation depending on wind direction relative to twist of rifling. L to R wind I adjust UP, R to L wind I adjust down. It is not much but at 1500 I have seen impact go low or high .5 MOA. 5-10 mph full value. I have not taken the longer shoots in heavier wind 15-20.

Not sure if you consider that environmental or not, but I do. Same as thermal activity in the mountains. Air moves and up and down with the terrain and depending on if I hug the mountain side or shoot over it, depends on what happens to my bullet.

 

[RobertB]

Brent,

Thanks for the response.
I have heard about this "roll" from shooting crosswinds at distance. I have looked for it best I can butmhardly any of my real long shots were made with conditions food enough to point things like that out to me. Variables were too much.

That's one reason I wanted to start this thread. If a shooter has most all aspects of the things that change impact at long distance then he will be able to point of smaller and smaller differences and errors. It has just been in the last few years I have been studying the subject and had the ability to goshoot different places at different distances

In lLA shooting conditions won't be near as different for month to month as it is in western regions.

When we get ti do our elr shooting is winter when the crops are down and its usually our windiest too.

Thanks again for the response. Sounds like you git it down pretty well.

 

[RobertB]

Forgive my auto spell and fat fingers. Lol

 

[BrentM]

It is a pain in the butt for sure. I was shooting 1500 yards one day and the wind was gusting L to R. My shots were stringing up and down as well as L and right. So I decided to shoot during the strong wind and plot the impact and then light wind and plot the impact. Elevation changed with the wind and at that distance it was easy to see it.

I am not convinced yet that lighter wind has enough of an affect for hunting purposes alone. I was shooting in a variable wind ( 4-7 ) last Friday at 1486 and 48 yards. Impacts in elevation were minimal. In fact, on paper my 948 yard impacts deviated less than 2". I was stringing L and R though. I was not too impressed myself on that but it did educate me, once again, as to how much affect conditions can have. 1.3 to 2.3 MOA is the wind affect in that shooting scenario. I adjusted .25MOA up for the wind, impacts were still about .25 low but wind variance high to low at 948 yards was almost 10".

I am constantly humbled but wind in the mountains. On the plains it doesn't bother me to bad.

 

[RMulhern]

Or you can use the S&HS method!

 

[4xforfun]

I use two different techniques. But let me state up front that I do not travel far when I hunt, and here in ND things are relitivly flat.

I make up a chart for my scope based on the forseen environmental perameters.. I know that the elevation is going to remain constant to within 200 feet and I look at the extended forcast to find an average temp. If it looks like there will be a wild swing in temps I will make up a new dial up and hold over chart....I do not mess with the wind chart.

I plug all this into my Seirra I6 program and make up charts for the top of my scope. See pictures.

I also have a kestral 3500 and the Shooter app. When I have time I use this most. I plug in station pressure, temp, azmith (ie 49th parallel), distance, and shooting direction and hit enter. It figures spin drift and coriolis. Absolutly AWSOME!!

The top chart is 9/3oclock wind from 5 mph to 30 mph out to 1000 yards im MOA...I have an NP-R1 reticle.

The second chart is dial ups using the forseen avarage environmental parameters from 350 to 1500 yards in 25 yard incruments.

The bottom is my holdovers (using 22 power) on my NSX NP R1 reticle.

Like I said, if there is time I go to the shooter...way more exact at extream ranges.

ALSO, DROPS ARE COMFERMED ON PAPER TO EXTREAM RANGE OVER MANY DAYS TESTING. Not just "print and shoot".....

Good luck,
Tod

 

[MMERSS]

I use two different techniques. But let me state up front that I do not travel far when I hunt, and here in ND things are relitivly flat.

I make up a chart for my scope based on the forseen environmental perameters.. I know that the elevation is going to remain constant to within 200 feet and I look at the extended forcast to find an average temp. If it looks like there will be a wild swing in temps I will make up a new dial up and hold over chart....I do not mess with the wind chart.

I plug all this into my Seirra I6 program and make up charts for the top of my scope. See pictures.

I also have a kestral 3500 and the Shooter app. When I have time I use this most. I plug in station pressure, temp, azmith (ie 49th parallel), distance, and shooting direction and hit enter. It figures spin drift and coriolis. Absolutly AWSOME!!

The top chart is 9/3oclock wind from 5 mph to 30 mph out to 1000 yards im MOA...I have an NP-R1 reticle.

The second chart is dial ups using the forseen avarage environmental parameters from 350 to 1500 yards in 25 yard incruments.

The bottom is my holdovers (using 22 power) on my NSX NP R1 reticle.

Like I said, if there is time I go to the shooter...way more exact at extream ranges.

ALSO, DROPS ARE COMFERMED ON PAPER TO EXTREAM RANGE OVER MANY DAYS TESTING. Not just "print and shoot".....

Good luck,
Tod

I like this. Simple yet provides all the data required for an accurate firing solution.
Great work and system!!!!!