Temperature change and accuracy question

[Dakota79]

Realistically how much does the temperature have to change to make your accuracy change?

For example if I zeroed my rifle when it was 30° out would I see much different when it is 50° out?

From my understanding the warmer the temperature the hotter the powder burns making your shot go higher as well.

I probably won't have to worry about it since my hunting is not long-range but just a curiosity question.

 

[TOGIE]

i'd be curious as well, but i guess more from a science perspective.

but i think you're right, for 98% of hunters, the effects will be negligible.

that said, i always seem to be sighting in my rifle in like 80-90 degree heat or more. then when it's time to take a shot on an animal it could be as low a 0 degrees. not a small temperature change.

 

[kwyeewyk]

Find an online ballistics calculator that has a temp variable to get an idea.

 

[Deleted member 16014]

Couple things come to mind that temp messes with:
1)Velocity (and pressure)
2)Relationship of bullet b.c. to air density
3)Action/stock interface

You have to isolate each variable to estimate the extent to which it matters. #1 and #2 can be plugged into a ballistics calculator. You didn't mention altitude but that too (higher = less air density = less drag).
Edited to add: yeah it doesn't matter at short to moderate distance.

 

[Bambistew]

IMO, unless you are shooting long range more than 3-400 yards or are really into target shooting none of it really matters that much. Even big swings in temperature, elevation, pressure etc is only an inch or two at 300 yards. Maybe all combined 3-4 inches at the most assuming extreme changes.

I doubt you could even tell the difference in POI with 20 deg difference in temperature.

 

[cahunter805]

Like stated the temperature change usually affects the velocity which can results in a POI change of a few inches at longer ranges. It most likely won’t affect your zero much though.
There are some powders that are not very temp stable also. RL22 is one that is very temp sensitive.
If you’re hunting in extreme cold I wouldn’t recommend storing your extra rounds on your stock but instead inside your jacket or at least in your pack.

 

[Don Fischer]

I have never worried about temp. Then again I have always worked up loads and zeroed rifles in cool spring weather. I can't imagine sitting at a table in 90* temp working on loads and accuracy. Was out shooting one time in late spring and to much temperature. How long do you have to sit and wait for a barrel to cool when it's hot out? Mine seem to never cool! Once the temperature get's up much past 70 I go out and plink. I don't have a clue if things change because of heat but most people believe it and then the powder company's make temp sensitive powder too don't they.

BTW, if I was going to the Artic to hunt in January I would not go out and work up the loads and sight the rifle in -20* weather either. Work up loads and sight in in weather comfortable for you then go out and plink in to hot or to cold weather and learn to use what you have.

 

[Whitetay]

Realistically how much does the temperature have to change to make your accuracy change?

For example if I zeroed my rifle when it was 30° out would I see much different when it is 50° out?

From my understanding the warmer the temperature the hotter the powder burns making your shot go higher as well.

I probably won't have to worry about it since my hunting is not long-range but just a curiosity question.

Depends on the powder and how well it does in big temp swings

 

[ImBillT]

Yes technically.

Use a stick powder and inside 500yds it generally won’t be too big a deal.


If you sighted in and made a dope chart on a 105 degree day with your ammo in the sun and might shoot to 500yds or more on 15deg morning, that might make me nervous. Could you second check all your dopes on a 50 degree morning before your hunt? You just might be 1-2 clicks off at 500+yds. Is that a lot? No. Can ten small errors that are meaningless on their own add up to a bad shot? Yes. If you might shoot in temps 80-100 degrees DIFFERENT from when you checked your dopes, you should probably make an effort to double check your dopes and at a temp that is at least a little closer to expected hunting conditions BUT IF YOU CANT, YOURE ALMOST CERTAINLY GOING TO BE FINE.

 

[std7mag]

Shooting 7mm-08 year round in central PA, we have wide temp swings.
With all the different powders i tried, POI was within 1.5" at 300 yards. That from 15° through 92°.
Worst temp sensitive powder i shot was CFE223. And is known to cause pressure issues if load developed at cooler temps then shot at higher temps.

IMR 4895, Varget, RL15, H414, all the 4350s, RL17, PP2000MR were within an inch POI shift at 300 yards through the forementioned temp shifts.

 

[VikingsGuy]

Yes technically.

Use a stick powder and inside 500yds it generally won’t be too big a deal.


If you sighted in and made a dope chart on a 105 degree day with your ammo in the sun and might shoot to 500yds or more on 15deg morning, that might make me nervous. Could you second check all your dopes on a 50 degree morning before your hunt? You just might be 1-2 clicks off at 500+yds. Is that a lot? No. Can ten small errors that are meaningless on their own add up to a bad shot? Yes. If you might shoot in temps 80-100 degrees DIFFERENT from when you checked your dopes, you should probably make an effort to double check your dopes and at a temp that is at least a little closer to expected hunting conditions BUT IF YOU CANT, YOURE ALMOST CERTAINLY GOING TO BE FINE.

I agree, but am more worried about a guy chasing velocity developing a load at 35 degrees and picking one that is just on edge of pressure signs, and then shooting it on a 95 day.

 

[Dakota79]

Shooting 7mm-08 year round in central PA, we have wide temp swings.
With all the different powders i tried, POI was within 1.5" at 300 yards. That from 15° through 92°.
Worst temp sensitive powder i shot was CFE223. And is known to cause pressure issues if load developed at cooler temps then shot at higher temps.

IMR 4895, Varget, RL15, H414, all the 4350s, RL17, PP2000MR were within an inch POI shift at 300 yards through the forementioned temp shifts.

That was helpful. Thank you.

 

[Millsworks]

Deffinately not the problem that many think it is for hunting.
It would have to be pretty extreme difference in temp. And a recheck of the zero in those conditions takes care of the problem for practical hunting distances out to 400, for sure.
Only potential problem is for max loaded reloads done at low temp then used at extremely high temps.

 

[mxracer317]

This is why I’m struggling to get my custom Leupold CDS turret. Maybe @Big Fin can chime in?

 

[Dakota79]

This is why I’m struggling to get my custom Leupold CDS turret. Maybe @Big Fin can chime in?

I have used the CDS turret on my .270 win and for my shot just under 400 yards it was a 50° difference in temperature from when I shot to what the turret was made for and I made the shot on an antelope.

 

[std7mag]

I shoot too many different weight bullets, and different brands of bullets for CDS to have any meaning.
I stick with MOA reticles & turrets.

 

[Arch Stanton]

Most environmental factors don’t matter until you get past 400 yds….

Most shots should be less than 400 yds….

Try the Hornady online ballistics calculator. Type in your load data. Play with huge temp differences, elevation difference, pressure, etc. it will give you confidence that not much changes until 400… give or take

 

[std7mag]

Strelok has a free version also.
With all the bullets (G1 &G7 listings), and reticle options it's hard to beat.

 

[Happy Myles]

I do not worry about temperature unless I need it for an excuse. For example, 30 years ago I sighted in my 300 WM at sea level on a summer day then three weeks later killed a Marco Polo ram at 17000 feet in a snow storm. If i had missed could have blamed it on the temperature and snow storm. Or my pounding heart. Kindest Regards. Oh, the shot was 305 yards according to my gauge.

 

[std7mag]

I do not worry about temperature unless I need it for an excuse. For example, 30 years ago I sighted in my 300 WM at sea level on a summer day then three weeks later killed a Marco Polo ram at 17000 feet in a snow storm. If i had missed could have blamed it on the temperature and snow storm. Or my pounding heart. Kindest Regards. Oh, the shot was 305 yards according to my gauge.

I'd have blamed it on the altitude & me gasping to try to get oxygen, but that's just me.