Sighting in during warmer weather than hunting weather

[Bigeclipse]

all,
How far off can point of impact change if you sighted your rifle in say 70 degree weather and then went hunting in below freezing? I will not be hunting long range on this trip coming up (maybe 250 yards) and I may not have time to check my poi before I leave in 2 days. Do I need to worry?

 

[huntinherrrington]

Depends on several things. First that comes to mind is powder. Some are extremely temp sensitive while other provide a near constant velocity with temp swings. Also will you be hunting/shooting at a different elevation at with your zero was established?

 

[Bigeclipse]

Depends on several things. First that comes to mind is powder. Some are extremely temp sensitive while other provide a near constant velocity with temp swings. Also will you be hunting/shooting at a different elevation at with your zero was established?

These are factory Hornady SST. 3006 and a 7mm08. If we were shooting 250 yards it would be on a field. Elevation is the same. All other shots would be in the woods at 100 yards or less.

 

[Canhunter35]

You will be fine.

 

[J E Custom]

You will not notice the difference in zero at 100 yards. You may see a little change in group size because of the Heat sensitivity of the powder and/or the primers ability to set off the powder in cold conditions.

All of the effects of cold on the rifle, primers, powder and firing pin strike
will be minimum.

good hunting

J E CUSTOM

 

[Bravo 4]

I concur, you'll be fine at those ranges. I zero most of my rifles at 100 except for my big gun, it's usually at 400 because I don't use it unless I expect shots in the range of at least 600...usually. If your zero is out in those ranges then there will be a change when you change environmentals.

 

[4xforfun]

You will be hit by a double whammy......slower velocity due to powder burn and the whole exterior balistics thing.....colder air is more dense...thus the bullet will slow down faster. At LR to ELR it would be a big problem....

BUT....at under 300 yards I wouldn't worry about it. With a 100 yard zero you would see less than 1/2 inch difference at 300 yards.

Good luck,
Tod

 

[smokepoler]

Agree with the others. 100 yards, the difference would be very minimal even with reloads and temp sensitive powder.

 

[Bigeclipse]

Agree with the others. 100 yards, the difference would be very minimal even with reloads and temp sensitive powder.

Thanks everyone. That's what I kind of figured

 

[cynicrit]

Done it many times. No problem. I suspect that it takes a very specific set of conditions before it is a problem ( i.e. very long ranges and/or extreme temperature variation). Super-long-range shooters or reloaders probably need to worry more. Ammo manufacturers try to specify or formulate powders to allow for a broad range of conditions.

 

[George Dean]

Check out Australian Outback's Extreme Weather loads performance. They may only make ammunition in .223 or .308 cartridge. But they post some interesting claimed results out to 600 yards for temperature ranges from 5 degrees to 125 degrees with the below cartridge.

.308 WIN – 165gr Sierra SBT GameKing

"Ballistic Temperature Independence

Our guys in white coats have developed a new line of ammunition that leaves your barrel at the same high velocity at extreme temperature ranges. No matter if it's scorching hot or freezing cold, Australian Outback ammunition delivers consistent extreme high velocity and ultra-reliability you demand in all shooting circumstances. For the technically minded, it's called Ballistic Temperature Independence (BTI). But all you really need to know is Australian Outback ammunition will never let you down."

 

[DavidleeCole]

all,
How far off can point of impact change if you sighted your rifle in say 70 degree weather and then went hunting in below freezing? I will not be hunting long range on this trip coming up (maybe 250 yards) and I may not have time to check my poi before I leave in 2 days. Do I need to worry?

 

[DavidleeCole]

I have a 300 weatrerby mag and it is zeroed at 100 yads shoot 180 gr. Nos accubond with 82.5 gr 7828 ssc. 3264 fps. At 70 deg. At 300 yards from 0 to 130 deg. I get .1 mill shift at 400 yards .2 mill at 500 .25 mill thats 4.29" so not much you may think but the furher you move out the more spread in inches you will have. I would suggest to use ballistics xrls 8.1 Or JBM ballistic calculators and check out the shift due to temp. As stated by another there is a lot more than powder burn rate that happens air density, air pressure and so much more. Under 300 for me I would focus on shooting fundamentals and the bullet drop the most and let the rest take care of it's self. Rember you will miss all the shoots you never take.