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- Thread starter ctrout
- Start date

Help Support Long Range Hunting Forum

Most people (but not all) can determine if water is frozen which gives you a clue that the temperature is above or below 32 degrees. Once that piece of information has been assimilated you can determine if you are wearing a T-shirt or if you have on a longsleeved shirt. This gives you an idea of whether the temperature is above or below about 50-60 degrees.

Humidity can be estimated at 50% unless it is too foggy or rainy to actually shoot and then it doesn't matter in the first place. Now then, if you are hunting horny toads in Death Valley then you can enter 0% humidity and will be all right. In other words try to avoid excessive stupidity when selecting an input.

Barometric pressure is moderated by altitude and if you correct for altitude you will be close to average value. Unless you are Miss Piggy and Lost in Space you will surely know whether you are standing knee deep in the surf of the Atlantic Ocean or at 9000 feet in the Rocky Mountains.

I often hunt with just a drop chart and a wind meter and leave the PDA in the truck. All of my drop charts have the conditions for which they were calculated on them and then they will have a "correction factor" for each 10 degrees of temperature and another for each 1000 feet of elevation at the range of 1000 yards. If a shot is presented that is beyond the reasonable accuracy of the printed drops then I will start mental math games with the correction factors.

If I have my PDA with me then I just enter my estimated temperature, altitude and humidity that seems appropriate for the situation in which I find myself.

It is easy enough to verify what I have told you. Go to your ballistic calculator and run your load at whatever your normal conditions are and write down the MOA drop at 500 and 1000 yards. Go back into the program and change only temperature by 10 degrees. Write down the MOA drops at 500 and 1000 yards. The difference between the first drops and the second drops is the "correctionfactor" Do this for all of the environmental variables and and you will be able to answer your own question.

The complexity of what I do is that you have to remember when to correct by adding and when to correct by subtracting and sometimes one factor will be added and one will be subtracted. And this may change as the day goes along and you move about and the sun warms things up or a front moves in.

If you are not very quick with doing math in your head then the easy option is to just use a PDA and average values and you should not be unduly embarrassed about it. Those of us who were given that gift usually have some deficiency elsewhere to balance it out.

So my advice is to make a few calculations with your ballistics program for your expected hunting conditions and rifles and see how much difference it makes.

Not a clear cut answer but the best I know to tell you considering the money difference involved.

no doubt many things can contribute to a hit or miss when shooting at distance. leaving ammo in a vehicle over a very cold night for example. how do we compensate for that?

the hunters in the area in which i hunt, are about as basic as you can get as for equiptment. ive never seen any of those type things used here.

certainly an accurate click chart is a must. but even that could change from day to day as bob indicated.

the simple solution to all these type of problems is to allways use a spotter.

a miss is a miss regardless of the cause.

good glasses, a good gun with an accurate chart, and a good rangefinder are all the essential tools needed. of coarse it goes without saying, a good rest, and good loads figure in also.

a small branch is all it takes to cause a miss. an unseen cause, but it could sure screw up your mind couldnt it?

use and trust a spotter if your serious about long range.

For my 257 Wby when elk hunting on the Manti in Utah I had a drop chart set up for 7000 feet altitude and wound up hunting right on top at 9000 feet. The altitude correction factor was 0.25 MOA per 1000 ft. at a range of 1000 yards. So for one thousand yards at 9000 feet I need 0.5 MOA less drop to be dialed in. The shot I finally took was only 450 yards which is only half of 1000 yards therefore I needed only one click to be taken off the drop.

The drop chart was set up for 50 degrees but it was cold with slushy snow on the ground so I estimated it to be just below freezing. The correction factor for temperature for that rifle and load is 0.1 MOA for every 10 degrees at 1000 yards. So with it being colder by 20 degrees and the air more dense I needed to add 0.2 MOA to my drop chart at 1000 yards. The shot was only 450 yards so I only needed to add half of that to the required drops.

Now the higher altitude requires MOA to be subtracted and the colder temperature required drops to be added. End result was I needed less than one click on the scope to compensate for the total changed conditions.

If the shot had been for 1000 yards, my total would have been -0.5 MOA +0.2 MOA = -0.3 MOA i.e. take off one click!!!

The drop chart was set up for 50 degrees but it was cold with slushy snow on the ground so I estimated it to be just below freezing. The correction factor for temperature for that rifle and load is 0.1 MOA for every 10 degrees at 1000 yards. So with it being colder by 20 degrees and the air more dense I needed to add 0.2 MOA to my drop chart at 1000 yards. The shot was only 450 yards so I only needed to add half of that to the required drops.

Now the higher altitude requires MOA to be subtracted and the colder temperature required drops to be added. End result was I needed less than one click on the scope to compensate for the total changed conditions.

If the shot had been for 1000 yards, my total would have been -0.5 MOA +0.2 MOA = -0.3 MOA i.e. take off one click!!!

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