50 above zero to 30 below will my
- Thread starter oneriver
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ttfreestyle
Silver $$ Contributor
Zero when you get where you are going or be sure to input your zero conditions on your app and save to defaults if your using one. It will change with temperature and altitude changes etc, how much will depend alot on what powder you are using.
At -30°F or C, strange things happen to lubricants. I would be concerned more with proper operation at those temps. People do hunt at that temp but not with regular lube. Currently at Cambridge Bay, Nunavut, Canada it is:
-37° | -45°
-39 F
FEELS LIKE -67° with a 13 MPH wind
The locals use seal oil or a wipe down with gasoline. It works for them and they are ALL meat hunters. Rifle works...you and family eat....it doesn't you don't.
Very interesting, thnx for sharing
Depending on how stable your chosen bullets are from your rifle you may find a change in bullet behaviour also. Bullets and shells can be a lot less stable at -30 than they are at +50 due to the higher air density, assuming the same altitude. Of course if you are much higher up at -30 then the air will be thinner and you will get back some of your stability.
There will also be a change in the speed of sound which may give slight changes in the way the bullets fly.
There will also be a change in the speed of sound which may give slight changes in the way the bullets fly.
There was a write up in Precision Shooting years ago about shooting in deep sub zero temps vs above zero temps. There were graphs and data showing what the effects were on impact, drop and over all gun function in various temps. Its an interesting article. Actually surprising that the differences were not all that much out to reasonable ranges. The function issues were however very noticeable with the rifles in the coldest temps. I do not remember what ranges they did these tests at but I remember thinking it did not seem to be a great difference in performance until the longer ranges were shot. Something like 100+/- fps difference at 500 yards with the .308 w/168s from 40° f to -40f. At closer ranges the difference was much less. I'm sure that article was long enough ago that with today's temp tolerant powders, those numbers may be lower even tho the test was based on exact same powders and bullets compared to each other.
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Make sure your barrel maker feels it's safe at those sub zero temperatures.
I've had primers that misfired at 10 Degrees F above zero.
Yes, your zero will change.
http://www.chuckhawks.com/firearms_cold_weather.htm
I've had primers that misfired at 10 Degrees F above zero.
Yes, your zero will change.
http://www.chuckhawks.com/firearms_cold_weather.htm
Don't forget how temperature affects how the shooter interacts with the rifle!
Simply stated, when it's 90 out, you're prolly shootin' in a t-shirt. When it's -10 out, safe to say that you're prolly wearin more than a t-shirt. Now, think of how the extra 'padding' might affect length of pull, trigger interface & sight picture. Not to mention how extra clothing would mitigate recoil and change how the pulse is transferred to your body position...
Anyhoo, that difference alone in mechanics of human/rifle interface might be enough to shift 'zero'. Not to discount other potential factors, but rather to make obvious one that isn't often discussed. And likely, one that matters quite a bit...
Simply stated, when it's 90 out, you're prolly shootin' in a t-shirt. When it's -10 out, safe to say that you're prolly wearin more than a t-shirt. Now, think of how the extra 'padding' might affect length of pull, trigger interface & sight picture. Not to mention how extra clothing would mitigate recoil and change how the pulse is transferred to your body position...
Anyhoo, that difference alone in mechanics of human/rifle interface might be enough to shift 'zero'. Not to discount other potential factors, but rather to make obvious one that isn't often discussed. And likely, one that matters quite a bit...
Your zero will change for sure...i shoot from +70 to -30 and there is a 1.5" drop from zero at -30 at 300 yds.
Running a 308 at 2880 with 168s at 300 yards 70°. Bullet drop(moa) is 3.9. Same data but -30 is a 4.1 drop(moa). Turns out with that cartridge, it's .75" difference from -30 to 70f. I didn't do a run from 0 to -30 but in my gun, it would be less. There's some difference but none that would be much on a larger animal. Definitely would matter on paper. Doubt the OP is shooting targets in -30. The 1000' elevation in my home state definitely is different than where you are shooting that 1.5" difference at 300 yards.
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I'll say thats a first. Barrel bore shrinkage with cold weather. I've experienced shrinkage in cold weather but it sure wasn't the bore of my gun barrel. No offense but I studied this quite in-depth and what seems to be the most affected issue of a gun barrel in sub zero temps is the barrels fatigue resistance. Metallurgists and barrel makers both have concluded this fact over and over. Stainless steel barrels are completely safe down too and beyond -55° but become more and more brittle beyond that. In fact the hunters comfort level will diminish so much so in temps below -30 that it's unlikely firing it will occur all that often. As far as temps shrinking a bore size and tightening the bore creating pressure issues is definitely something I haven't heard of. Again, I'm no metallurgist nor qualified barrel maker or gunsmith and cannot say it is not true. Just from a common sense perspective, doesn't seem possible. Maybe in a polymer or synthetic property object, I'd say absolutely.
I have assembled wear sleeves on shafts where i needed to put the shaft in sub zero freezer and heat the sleeve up red hot to get it to slide over the shaft. If one wasn't cold or hot enough it didn't slide on at all. But when they were where they needed to be it slid on like butter. You had one chance and only a few seconds to get that sleeve on. The metal in the barrel or even fine tuned extremely crisp trigger can't disobey the explanation or contraction due to heat or extreme cold. Maybe some metals expand or contact less but i feel is something to consider when shooting in extreme cold. I've hunted coyotes in those temps. At least a couple times every year. I should put a Mic on the barrel and see how much the does change when it gets that cold.
I'd be curious of your results. Wouldn't be that difficult if a deep freezer was used.
Where i was working at the time and a freezer that would go down to like -40. Common deep freezers don't go that low but I've never checked house cold they get.
Yes I think residential deep freezers probably go down to -20 or so. Either way, I'd think that would be cold enough if there was going to be a change in dimension.
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