freezing ammo/accuracy change??

[Buckythebrewer]

Just got done reloading some ammo in a COLD room(temperature outside-4 to -14 lately with HORRIBLE WIND CHILL).Has anybody ever tried freezing there ammo and then check for any accuracy difference?
What Im saying is taking ammo that you know shoots well ,and then freezing it,,and checking to see if the accuracy increases or decreases?..

[mutski]

I live in Fairbanks, and I've noticed a decline in accuracy at the outdoor range when temps are well below zero. Not sure the cause, though - light is poor this time of year, it's harder to see the sights. My fingers get cold... Do chattering teeth affect accuracy? I have shot some nice targets in the cold using a .22 pistol, which has a red-dot scope to eliminate the low light problem.

I've heard from others that some powders actually give more pressure when cold, and can overpressure the chamber. But on first glance in my new ABCs of Reloading, I see no reference to that. Anyone know which powders? The shooter who told me said not the once in factory loads; it's a problem for home reloaders.

[Ifishsum]

I've heard that Alliant Blue Dot actually increases in pressure as it gets cold, but I don't have anything to back that up, just read it somewhere on the net. Most powders will lose some pressure in colder temps, Hodgdon's Extreme series is supposed to be less sensitive to this. I have noticed with some .204 loads using BL-C(2) that I worked up to top accuracy at 60 degrees F don't shoot quite as well at 100 degrees, and seem to have primers flattened a little more than usual.

[Buckythebrewer]

My friend and I talked about this.He mentioned frost from freezing it effecting head spacing,And then I mentioned the cold causing the cases to shrink making up the difference.Pressures increasing?Thats intresting.I think im going to take a cartridge at room temp and measure the headspacing.Then I am going to freeze it outside at probably 10-20 below freezing,And measure it again.
I am curious as to how far it will shrink.

[Shoney]

I have never been self abusing enough to target shoot at sub zero temps. I have, however, hunted and taken game numberous times at sub zero temps as low as 44 below.

Because of the clothing and conditions, I was never able to tell if the weapon's accuracy was affected (mine definitely was). When cutting up the game, it was apparent that the effects of the bullet on the animals were definitly reduced. Pentration and wound chanels appeared to be less than those of the same bullet/load/weapon at 10 degrees and up.

I am not convinced that the powder is the only culpret. I believe it may be a combination of factors: sub zero ambient temperature effects
1. shrinking of metals (barrel and cartridge)
2. primer ignition
3. powder
4. does the low temp copper create more friction?

The amount of metal shinkage may be minimal (in the thousanths) but that may be enough to cause more friction of barrel to bullet without an increase in pressure from the powder burn.

[Edward429451]

This is interesting. My HVAC experiance taught me that pressure / temperature relationships cause higher pressure with higher temps, and lower pressure with lower temps.

My instinct tells me that this pressure / temp relationship very probably could be applied to other things besides A/C.

Maybe I'm being presumptious. I await an engineer / scientist type to post and teach us all something more, or confirm my present belief.

[Buckythebrewer]

shoney,44 below?Yikes .Thats nice stuff to know.I have noticed on cooler days it is very nice to shoot long ranges(600 yards anyways) because of the ability to use higher power on the scope(targets only obviously).There is no mirage when I have shot on those days.The same goes for looking at a radio tower a mile away from my house.On 32 x on a cold day the air seems to be crystal clear and everything is easily visible and clear(parallex adjustment set to infinity)..My best shooting have been on cooler days heading into fall, at 100 yrds, or 600 yrds,,I seem to get better results.
I don't believe my target shooting will be good ON COLD(freezing or below) days however,And I don't get out much on those colder days to try it often enough to know for sure.
I will shoot soon (and its going to be COLD) to see if my groups with these loads go all to hel* or not.Im trying some 55gr vmax for the hell of it and using up the last of my imr3031 that Im sick of metering

[OlderFox]

Check this out.

Quite informative and detailed.

http://www.shootingsoftware.com/ftp/...%20Factors.pdf

Cheers

[tINY]

Temperature will change a lot of things. But if you are target shooting, it's the temperature of the chamber that is most significant.


-tINY

[castnblast]

Temperature has a far less effect on extruded powders than non extruded. Hodgdon seems to have nailed this w/ their extreme powder serries... They are supposed to have the least variance (so their marketing and test results say) than others. I tend to believe them, or I just bought into their marketing... I have noticed on the other side of the spectrum that I don't see a huge difference in extremely hot conditions...It does not get that cold down here, but it gets pretty darn hot! We deer hunt in shorts the majority of the season...

[rnovi]

Exact case in point: .350RM. Using IMR 4895 I get an honest 2700fps out of a 225gr. Sierra GKing in summer.

Winter Chorno work here in SoCal (on a 35 degree day) and I saw my load velocities drop to as little as 2550fps.

A 150fps drop in velocity - dang that's pretty extreme. But that's what I'm getting.

For me, the real question is: would dropping 150fps change accuracy? Well, it sure could change the point of impact. In theory it's possible that the velocity change could also put the load outside of it's accuracy variance.

I shoot a 1.5" group during winter and a (barely) sub 1" group during summer. Dunno if this is caused by me shivering or not though. I'm not all that great of a rifle tester.

In my case though, i'm going to switch to H4895 and see if there is much of difference...

[Buckythebrewer]

Tiny,That would make the most sense.The chamber starting off very cold ,then as shots increase the temp increases causeing the chamber to expand,,Then changing pressures.At least it makes sense to me.

[mutski]

(Moved post - meant to start a new thread)

[OBIWAN]

The other day it was -3 when I was out shooting

I noticed no difference in performance

Other than some loss of feeling in my trigger finger

But I don't think that was ammo related

[castnblast]

Checkout Hodgdon's web site regarding testing they did w/ their extreme powders serries. They tested Benchmark powder w/ I don't recall what load, and over a 125F temperature spread, they claim the following. www.hodgdon.com/smokeless/extreme/page2.php#top You'll see your problem w/ IMR is consistant w/ the testing Hodgdon states on their site. H4895 shows a 20 fps variance, while IMR has a 166fps variance over a 125F temp spread.

Benchmark has an 8fps spread, and so forth. See the data for yourself.

[Thesenator]

Hirtenberger loaded 9mm+P+ ammo supposedly for use in Sterling submachineguns in arctic temperatures. I use it in an Uzi and its hot stuff in normal temp ranges. It increases the rate of fire very noticeably compared to standard velocity 9mm ammo. It's accurate and shoots very flat at 100yds. Out of a pistol (the Ruger P85 which will handle the pressures no problem) it shoots point of aim at 100yds compared to standard 9mm which drops significantly at that distance.

I've never used or chronoed any in extreme cold (subzero) so I can't verify any differences between temp extremes but I suspect it's a valid conclusion that it works better than standard 9mm.

Rifle ammo may be less effected by temp extremes than pistol ammo as I've never heard of any specific arctic military rifle ammo designs, only the Hirtenberger 9mm.

Basic chemistry dictates that chemical reactions usually slow down in extreme cold but I don't know if the changes that occur are due to mechanical or chemical reaction discrepancies from the effects of extreme cold. Maybe its a bit of both, I don't know.

It's an interesting phenomena and worthy of some study, I just don't have the equipment, time or conditions to experiment. I'll leave that to the powder/ammo companies or people who live in those conditions and take their word on their results.

[Edward429451]

Soo, no evidence of increased pressure at lower temps. Standard pressure/temp relationship still applies. Possible increases in pressure can be expected from hot chamber. Ambient air temp has little effect, while ammo core temp does have pronounced effect.

Careful where you store your ammo. Careful with hot loads in a hot weapon.