temperature affect on POI

[nmarchr]

I have a couple questions before my upcoming colorado deer hunt. I live at 6500 feet, and will be hunting deer between 7K and 9K feet this year. I got a new gun this summer and have spent a lot of time shooting all year. I took it to the range this past weekend to verify everything was still dialed in and ready to go. I set up at 500 and used my app and boom, dead on at 500 yards. This is where i start overthinking things. It was 75 degrees where I was shooting this weekend. During my hunt temps will more than likely be in the 20's and 30's or colder. When I plug those numbers into my app I notice that my bullet drops a lot faster. that same dope at 500 yards could end up in a clean miss for me. Do you all make different dope cards for the conditions you will likely be hunting in, or am I overthinking this process? Would really like to hear what some of you more experienced rifle hunters do in these types of circumstances. I am an archer that does not gun hunt a whole lot. any help is greatly appreciated.

 

[WHT_MTNMAN]

Yes it will make a difference at anything over 350 yards, for sure at 500+
I would make a new dope chart but if you have time run the app again with all of the new variables before you shoot. Just my .02

 

[littlebighorn]

I always carry a dope chart for the conditions I will be hunting in.
You will know general altitude and temperature, etc. I pick an average and go with that.

 

[Flyjunky12]

First thing, use density altitude.

Are you sure your app is correct? I plug those numbers into my app and there is hardly a difference, especially at 500.

 

[roadrunner]

Yes it will make a difference at anything over 350 yards, for sure at 500+
I would make a new dope chart but if you have time run the app again with all of the new variables before you shoot. Just my .02

This. I use the poor man's version of Strelok and when you change altitude and temp, the POI does change from sight in conditions.

 

[Flyjunky12]

This. I use the poor man's version of Strelok and when you change altitude and temp, the POI does change from sight in conditions.

At 500 using a 6.5 creed with 140 eldm travelling at 2900 (totally made up) I get:

6500’ 70 degrees….8.63moa
9000’ 20 degrees….8.84moa

This is using 4dof,shooter app, and for the heck of it ran it against berger’s simple ballistic calculator. I also checked it against density altitude charts and those numbers are correct, virtually no change.

Maybe I’m missing something but I shoot out to 1400 every other weekend all year and I’m well versed in ballistic calcs. Please take a screen shot of your app that shows a big enough error that a shooter would completely miss a target at 500 because of those environmental differences. FYI, I’m not being argumentative, just trying to find where i might be going wrong on this.

 

[roadrunner]

@Flyjunky12

Hopefully these make sense. Screenshot of sight in conditions followed by the drop table (sorry, didn't change to zero conditions, first screenshot is the conditions from an off range oryx hunt in Jan. Oops, but you get the idea.)

Screenshot of altitude change with temperature changes (20 deg and 5 deg).

 

[Flyjunky12]

@Flyjunky12

Hopefully these make sense. Screenshot of sight in conditions followed by the drop table (sorry, didn't change to zero conditions, first screenshot is the conditions from an off range oryx hunt in Jan. Oops, but you get the idea.)

Screenshot of altitude change with temperature changes (20 deg and 5 deg).

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Thank you. That’s interesting, I can’t get my numbers to move that much.

 

[nmarchr]

Thank you. That’s interesting, I can’t get my numbers to move that much.

Maybe the BC of the bullet??

 

[Flyjunky12]

Maybe the BC of the bullet??

No, that won’t make that much of a difference.

Here’s a density altitude chart and between the 2 elevation/temps there is only about 600’ difference….in essence, nothing.

 

[Zeke]

I've noticed little difference in true trajectory but I love to study and tinker so I try to be as precise as possible for the guessed conditions in which I'll be hunting.

"Usually" the temp goes down (denser air) and the elevation increases (less dense air) and they almost cancel each other out.
I find it hard to dial less than .25 MOA. Study, tinker. shoot as often as possible (don't be lazy or cheap) and be as precise as you can but at 500 yards, it shouldn't make very much difference. IMHO.

Zeke

 

[Flyjunky12]

"Usually" the temp goes down (denser air) and the elevation increases (less dense air) and they almost cancel each other out.


Zeke

Exactly why I posted that density altitude chart above. Very little difference in the OP’s situation, matter of fact it would be hard to shoot the difference.