Okay, we've all heard and experience powder which is temperature sensitive so here's the 3 dollar question:
Which powders are supposed to be less temp sensitive?
(specifically rifle cartridge powder and even more specifically, 4350/4831+/- burn rate powders for a 280 AI)
Thanks for your insight.
Zeke

Since I load my various 280s and most others with RL powders which are supposed to be VERY sensitive and have no issues. Only thing I can relay is the "PRESS" feels the various SC powders are "great" as to temperature

I've only been loading for 45 yrs or so and have "NEVER" made a reloading choice or decision based on if a powder was supposed to temperature sensitive or not.

That's almost as long as I've been reloading too but if this old dog can learn a new trick, I will.

As with you, I've NEVER made a decision based on temp sensitivity but if there is a "slight" advantage, I'll take it.

Thanks for the input, Paul.

Zeke

quote:

but if there is a "slight" advantage, I'll take it

What is the advantage?

The advantage is not evident if you don't load at the max, or you don't shoot much past about 400-500 yards.

If you do one of these two, you will not get overpressure issues at high temperature, and you will get more consistent shot placement at long range.

I have seen a couple of instances of a hard opening bolt when the temperatures got up to the high 90's while shooting prairie dogs. At 70F in the morning, no issue, at 90F in the afternoon, very sticky extraction.

The Hogdon extreme series is a good start. H4350 and H4831 are in that series. H1000 might be an interesting choice for a 280AI if you have a 24" plus barrel and want to shoot heavy bullets. It works well in my 30-06AI with 200gr bullets.

Here is data published by Hogdon: http://www.hodgdon.com/smokele...xtreme/page2.php#top

All this said, there is some hype here as other factors can influence the result.

Jeremy

Supposedly the "advantage is more consistent velocities over a wider range of temperatures.

Are you telling me, Paul, that you see no advantage in keeping velocities consistent? Are you saying that one should only shoot and catalog ballistics and drop charts for the temps which a shooter will encounter on the day he gets a shot?

There's lots of load development during the summer and lots of hunting during the winter so I'd think any gain would be good.... but maybe NOT significant.

No doubt that anyone shooting/hunting under 300 yards might not realize the advantage but for some "western" hunters who regularly shoot farther, an advantage might be welcomed.

What do ye think?

Zeke

Thanks Jeremy! Good place to start with my new rifle.

I suspect it's asking too much of me to go back to load development for the other 20+ cartridges for which I reload but maybe worth is on this one since it's brand new.

Zeke

First a couple thoughts. IN MY OPINION If a load is too "hot" in hot weather it is too HOT period. If a 20deg rise in temp blows a primer you are WAY to hot anyway. My 2 cents on that one.

I load a bunch of RL22. RL19 and RL15. I've never seen more than an 1" difference out to around 400yds that I would base on Temp. You can see that much difference same temp going from sea level to the mountains.

For years I would worked up my loads in Houston and come to the mtns west Tx etc. I would take my sea level load and re-sight it at 200-300yds based on where I was hunting. Yes there was a difference. Even 100fps isn't going to really effect your Max Point Blank range. Just checking 160s in my 280 the effect of 100fps is 12yds. 100fps in my opinion is an extreme spread.

All I'm saying is I go for the most accurate load. I have never seen temp play a key role. I think a reloader needs to do what gives him confidence in his rifle and shooting.

I STOLE THIS ARTICLE : Rifle Shooter Mag I believe.

It was hot, July-in-Utah hot. I chambered one of the special handloads I’d developed six months earlier and shot at my 400-yard gong. I missed. Worse, when I opened my action, smoke poured out of it and a loose, soot-blackened primer fell out of the base of the empty cartridge case.

I’d developed that handload in 20-degrees Fahrenheit. Clearly, the heat had caused a pressure spike.

Heat can not only turn apparently safe handloads into dangerously hot handloads, but — legend has it — it also affects velocities and can cause shots to go awry.

Some gunpowder has the reputation of being particularly susceptible to variations in temperature. Alliant’s Reloder line is one, for example. Others, such as Hodgdon’s Extreme line, are purposely designed to be stable in extremes of heat and cold.


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Trouble is, many propellants with a reputation for instability in extreme temperatures are very good powders that make assembling accurate hand loads easy. Reloder 22, for instance, is my all-time favorite powder for magnum rifle cartridges because it is quite easy to get it to shoot well.

The question we’re tackling here is threefold:
1. Is gunpowder sensitive to temperature swings?
2. Are some propellants more temperature sensitive than others?
3. If so, are the velocity variations caused by extremes in temperature enough to change point of impact at hunting ranges and cause a miss on an animal?

First, let’s establish what “hunting ranges” means. Most hunters have no business shooting at game past 300 yards, but we’ll give ourselves the benefit of the doubt and make 400 yards the outside parameter of our standard, common, hunting-range category.

But what about all the long-range shooters out there now that consider connecting on a deer at very long distances to be the greatest “trophy” of the hunt? To them, 400 yards is close. So if temperature-induced velocity variation does indeed occur, let’s also examine the effect on point of impact at 800 yards — double our typical “long” distance.


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To test whether temperature-induced velocity anomalies are fact or fiction, I loaded 10 rounds each for the 7mm Remington Magnum, a popular long-range hunting cartridge. I used Nosler’s 160-grain AccuBond and two propellants, Hodgdon’s H-1000 — which has a reputation for stability in temperature extremes — and my old standby, Reloder 22 — which has a reputation for volatility in temperature extremes.

Each batch was loaded with charge weights near maximum but previously proved to be safe in that particular rifle.

Half of each batch I put in the freezer overnight. The next morning, I set the ammo box on the dash of my truck and let it sit in the August sun until after lunch, by which point the interior of my pickup was stiflingly hot. Thus prepared, I loaded up my chronograph and rifle, put the frozen ammunition in a small cooler with several ice packs and headed to the range.

Ideally, I’d have frozen the rifle between each cold-round shot, but, unfortunately, the range doesn’t have a deep freeze, and I wouldn’t have had time if it had. To minimize the effect of a warm chamber, I attempted to send each shot through the chronograph screens within three to five seconds after dunking the cartridge into the action. I also allowed the rifle to cool — as much as it would on a 95-degree day — between five-shot strings.

With frozen-ammo velocities in the bag, I then shot the ammo still cooking on the dashboard of my pickup. The cartridges were hot to the point of being uncomfortable to hold.

The result? The answer to the first of our threefold question is yes: Temperature extremes do affect velocity. Both propellant types shot significantly higher velocities with the hot ammunition.

The answer to the second question is also yes: The disparity was much less with one propellant brand/type than with the other. Specifically, H-1000 had 44 fps disparity between temperature extremes; RL-22 had 130 fps disparity. The difference between propellant types — 86 fps — was significant.

Here’s a breakdown of the results with each gunpowder type:

Hodgdon H-1000 Frozen Hot Difference
Velocity (fps) 2,892 2,936 44
Extreme Spread 70 12
Standard Deviation 25 5

Alliant RL-22 Frozen Hot Difference
Velocity (fps) 2,972 3,102 130
Extreme Spread 34 6
Standard Deviation 14 2

As an aside, an effect I didn’t foresee was that hot ammunition — at least in this case — is more consistent than cold ammo. Take note of the far tighter extreme spreads and standard deviations.

To answer the last of our threefold question (is temperature-induced variation enough to cause a miss at hunting ranges) we need to run some ballistic calculations. Keeping things very simple, I used the calculator on Hornady’s website and plugged in the appropriate numbers. Here’s what I found:

With RL-22 powder and a 200-yard zero, the 160-grain Nosler AccuBond (B.C. .531) will drop 18.8 inches at 400 yards with the frozen ammo and 17.1 inches with the hot ammo. The difference is less than two inches. With H-1000 the difference is less than one inch. So the answer is no: When using a temperature-sensitive propellant, even extreme swings in temperature won’t cause enough disparity in point of impact to make us miss a game animal.

How about for long-range shooters that really stretch the distance? Let’s double the distance and run the numbers:

Again with RL-22, the projectile drops 144.5 inches with the frozen ammo and 131.2 inches with the hot ammo. The difference is 13.3 inches, which is certainly enough to cause a complete miss on a deer-size animal, and a miss — or worse, a wound — on an elk-size animal. Clearly, as distances stretch, temperature sensitivity becomes far more critical.

Let’s look at H-1000: At 800 yards, the bullet drops 153.8 inches with the frozen ammo and 148.6 inches with the hot ammo. The difference is much less, only 5.2 inches. Depending on the size of the game, that’s still enough to potentially cause a miss, but the disparity is more acceptable.

We don’t have space to address it here, but another element that exerts additional drag and drop on cold ammunition is the density of colder air. Lower temperatures result in more drag on your bullet, which will open up the disparities shown above even more.

The multifaceted nature of this “fact or fiction” topic bars a simple yes or no answer, but we can come away with this:

Yes, temperature does affect velocity, and it affects some propellants more than others.

However, within common hunting distances out to 400 yards or so, the disparities are little enough that we don’t need to worry about them.

If you shoot long range, though, you’d better be familiar with your velocities and the trajectory of your bullet in the conditions in which you’ll likely shoot. If you hunt in very cold weather, get out and practice in very cold weather. Leave your rifle and ammunition out to freeze overnight, and chronograph your ammunition. Then plug those numbers into your ballistic app.


Read more: http://www.rifleshootermag.com...ivity/#ixzz3XygILogm

Paul,
I totally agree: If hunting ammo is too hot in hot weather then it's loaded to hot.
That wasn't really my biggest concern. My concern was a drop difference in cold temps when the load was developed in hot weather.
Good article. Thanks. It appears that it would make a difference at extended ranges but probably not enough to worry about unless a guy is shooting well over 5-600 yards... and I won't shoot in a hunting situation any farther.
I have to admit that I've never done the hot v cold tests for myself but I knew someone had to know something.
Thanks for the input. It looks like I'll stick with RL-22 or 19.
Thanks,
Zeke

quote:

It looks like I'll stick with RL-22 or 19

Load what is accurate and worry about the BIG things.

quote:

Originally posted by ramrod340:

quote:

It looks like I'll stick with RL-22 or 19

Load what is accurate and worry about the BIG things.

Ain't that the truth!
Seems to have worked for my reloading for almost 50 years. Maybe I was just getting too "tricky". ha

Zeke

You may find this interesting. It is cut and pasted from Ramshot Powders FAQs.

Most of our powders are not insensitive, and will show some effect at hot and cold temperatures.

However, we test at -40F and +125F and the deviation in most cases are ca 3% to 5% at these extreme levels. Therefore most shooters do not notice much difference under normal practical hunting conditions.

More elaboration on the subject:

Complete temperature stability can only be achieved with tubular extruded powders designs, either with double base (NG) and/or with other coating technologies.

Because the ballistic performance at extreme temperature is completely dependant on the specific combination, it is very difficult to quantify and qualify.

Our standard powders perform very well at extreme temperatures, and usually pass the strict military requirements by a large margin.

This is a subject that often fraught with misconceptions and inaccuracies.

The term is used loosely by manufacturers without qualifying the subject, and is obviously exploited for marketing purposes and perceptions.

The facts are:
•Although powders can be improved, it’s really only possible with advanced coating procedures and additives which increase the cost.
•A particular powder can be improved re temperature stability for certain combinations, within a certain envelope which is specific to the following three main parameters/aspects
◦The caliber.
◦The weight of the projectile/bullet.
◦The performance level.


If any of these parameters/aspects go beyond or outside the intended ratio/s, the results will change and the performance will sometimes be different.

It is also very important that when a comparison is made, that all conditions re weapon i.e. components primer, case, bullet and the velocity are equal, and preferably done at the same time on the same day.

Most of the common Hodgdon powders are made in Australia by a company originally called Australian Defence Industries (ADI). The company is now called Australian Munitions but still calls the powder ADI.

The company began life loading ammo for the Australian military (and others) and naturally enough focused on non-temperature sensitive powder due to the hot conditions encountered in Australia and also the hot conditions (Middle East and Asia) where the Aussies may be operating.

H4350 is just AR2209, H3831SC is AR2213SC, and H1000 is AR2217, Varget is AR2208, and some of the other Hodgdon powders are also ADI manufactured.

The full ADI reloading book is a free downloadable book on the ADI website and contains a lot of info on their powders and relationship with Hodgdon among others.

Damn good powder and readily available in our neck of the woods of course.

[QUOTE]Originally posted by ZekeShikar:
Okay, we've all heard and experience powder which is temperature sensitive so here's the 3 dollar question:
Which powders are supposed to be less temp sensitive?
(specifically rifle cartridge powder and even more specifically, 4350/4831+/- burn rate powders for a 280 AI)


What are you looking to accomplish ?.

Further to what eagle27 posted. The Aust Defence wanted to load the same powder in their 5.56, 7.62 etc foruse in Antartica to the middle of Aust in summer. If powder burn rate/ pressure varies to much then this can affect the reliability of semi and full auto weapons.

I disagree with the statement that if a load is to hot in summer than it is to hot period is rubbish in my view. Using IMR powders in my 270 proved problomatic. If I used a load worked up in summer in winter I would of been using an anemic load for the 270. Using AR2209 I have never had to worry about temp effect on the 270 and I can still run it at 270 velocities, not 308 speeds.

Iunderstand Re17 is said to temp insensitive.

I suspect this concern originated with the old Cordite propellants, which were notoriously heat sensitive.

If a shooter is worried about this, he should also be informed regarding the effect of elevation and air density on the bullet's flight.

Personal testing In SoCal showed fairly varied velocities from winter months (40 degrees at the range) and summer months (95+) at the range. I remember thinking that my Chrony just had to be off significantly.

What I did find is that as velocity dropped, my POI shifted, in some cases by as much as 2". Obviously I had fallen out of the sweet spot for accuracy. That was the key - the 100 fps doesn't really change killing power. it did, howe eat, significantly change poi.

I've found that H4350 and H4831, while slightly down from max velocities gave me much better and more consistent overall performance.

At this point I pretty start and stop with the Hodgdon extreme powders these days. It's just easier for me.

quote:

Obviously I had fallen out of the sweet spot for accuracy.

Very valid point.

I remember back in my younger days. Spending hours getting that special load. Then going hunting or even back to the range only to find that .5 MOA " load was now a 1MOA. At the time not even thinking about temp. Just playing and recording data over the years I "think" many of my more accurate loads had much smaller windows.

Early on it was MAX VELOCITY and accuracy. Now it is ACCURACY and velocity. So I would look for those little accuracy spikes at max velocity. Now using the ladder procedure as an example I look for the plateau with 4 or 5 grs. So slight variations don't make that big an issue. If I find that plateau doesn't give me acceptable velocity then I change powder. I no longer spend hours and 100s of rds looking for that super tight group.

Now days if it is sub MOA every time I'm a happy camper.

As I've said before a reloader needs to do what gives him confidence. You simply needed to feel that your rifle and load is going to put the bullet where the crosshairs are. If that is seasonal loads, different powders, whatever. If you question your load you are already in trouble.

I too use a lot of RL19 and 22, and I have noticed a measurable difference not in accuracy, but in point of impact due to temp. Most of my loading R&D is done in the late winter early spring and then proving and re-proving in early summer and early fall. Everything stays pretty consistent until temps get down in the -15 to -30 range. That is where POI will move as much as 2". This change has been observed with RL, IMR, and Hodgdon powders. Could be powder, could be thermal contraction of the rifle and its parts to include optics and mounts. Fortunately I seldom have to hunt in these conditions, but when I know I have a week of that ahead, I will re-zero a cold weather rifle.

I appreciate all the input.
To shed some light on my query, I'm a little concerned with POI at longer distances and extreme temp chance. ie: working up a load at 78 degrees and doing all the drop-charting-doping during "nice" weather months and them hunting at below zero degrees for animals (not paper targets so I want to be as consistent as humanly possible)!

Sure, we all know that within close ranges (to 400 yards) elevation, temperature, pressure makes very little difference BUT IT'S BEYOND THOSE RANGES WHERE WE POTENTIALLY RUN INTO ISSUES so rather than dismiss it as a non-issue, I decided to turn to some other shooters. You guys.

It's fun to shoot for days on end in nice weather but I don't care to shoot when it's super cold although I'll hunt in it every chance I get.

Sure, most of you don't care or don't need to know. That's Ok, but I feeling like my same old anal self right now.

From what I've gleaned from this thread, so far, is that temp will probably have some impact (pun intended) with every powder but I can see where it's become a marketing tool for the powder companies.

Thank you all, again, even though some of you make perfect sense and other are a bit hard to follow (maybe I am too).
Zeke

I live where the temperature can swing between 100F in the summer to -40 on winter. I work up loads in summer but try to do it on a day or evening where temp is 80 or less and most of my hunting is only to -20 or so. When I work up loads I try for greatest accuracy, not necessarily the maximun. But when i shoot those same loads to sight in, I have several rifles (not all) whose point of impact changes considerably from the summer sight in. Usually the point of impact moves down about 2 inches and to the left about 2 inches at 100 yards So I have to re sight my rifle for the season.. I used to use and still do the older imr 4350, imr 4895, H4831 and winchester ball powders. I now use Hodgsdon extreme powders. With the newer less temperature powders that problem does not exist or at least it is not as severe.

To the previous poster. I am not an engineer, but I believe air density when its cold affects drop at long range, because even when i resight, and add one or two grains of powder to keep the velocity constant with summer velocity, I still get somewhat greater drop at 300 yards than i did in the summer. Hope this helps.

quote:

To the previous poster. I am not an engineer, but I believe air density when its cold affects drop at long range, because even when i resight, and add one or two grains of powder to keep the velocity constant with summer velocity, I still get somewhat greater drop at 300 yards than i did in the summer. Hope this helps.

Actually it is simply barometric pressure. So altitude, temp etc effect it. .

Some interesting reading.

http://www.exteriorballistics....bexplained/index.cfm

If you have time on your hands. Play with the temp, altitude etc. on http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
Yes it doesn't calculate the temp effect on powder but does do a pretty good job on external impacts. I'm pretty sure you will find altitude has far more impact than temp on external ballistics. Out to 300-400yds the impacts are still small.

[QUOTE]Originally posted by ZekeShikar:
Okay, we've all heard and experience powder which is temperature sensitive so here's the 3 dollar question:
Which powders are supposed to be less temp sensitive?
(specifically rifle cartridge powder and even more specifically, 4350/4831+/- burn rate powders for a 280 AI)
____________________________________________

Not an easy question to answer, but ------:

Hodgdon IMR and Accurate all make 4350. From information gleaned the Hodgdon seems more stable than the IMR. H4350 has a commendable reputation as being temperature insensitive.

Proving the matter of temperature on gunpowder performance is really complicated. Some work was done by experimenters who froze the ammunition in a freezer overnight in August and left another batch on the dashboard in the glaring sum. The frozen ammo was taken to the range in a cooler packed with ice. After the first shot the chamber/barrel is HOT! So ?

Generally, in broad terms, gunpowder comes in 3 basic shapes, stick, ball, flake. It is either single base, nitrocellulose, or double base nitrocellulose with nitroglycerine. And some is coated too. Different powders react differently to temperature extremes in both directions. Heat tends to degrade the nitrocellulose. Cold makes the powder more sluggish.

Generally, in broad terms, there can be a difference in velocity from 20 fps to over 100 fps.

At 300 yards bullet drops were found to be 1" to 2" difference. At twice that range drop difference could range from 9" to 18".

As for accuracy high heat could cause fliers and also really dangerous pressure spikes. Extreme cold seemed to be less influential subduing the volatility.

There are bench rester's and there are hunters. BR's normally don't shoot in sub-zero weather, nor over 100 degrees Fahrenheit. Most hunters hunt in a range of temperatures that are not the extremes - in most cases.

A change in point of impact at 300 yards of 1" to 2" isn't super critical. 600 yards may be a different story.

I have often shot running game offhand. Even once from a moving boat bobbing up and down, and connected. Ranges were around 200 yards. It was really not at all difficult since I mastered the eye trigger - pull coordination many years ago. Sometimes first shot, sometimes 3, once 5.

It's truly a Hail Mary. To me a 1" to 2" difference in point of impact, extreme cold to extreme hot is essentially on the outer fringes of being little if any concern. Too many other elements enter into the mental computer, wind direction, velocity, angle of shooting up -down, bullet placement, penetration.

For more info why not phone Hodgdon. The guys there that I speak to are very friendly, helpful and honest.

YIKES! 2" at 100 yards! That's a game-changer for sure.

I've checked "zero" in super cold temps and never seen POI change to that degree but I suppose it's possible.


I appreciate all the contributions to this thread.

Thanks, Zeke

quote:

YIKES! 2" at 100 yards! That's a game-changer for sure

I'd bet a that is simply a very picky load and a slight change opens the group up. BUT, I've been for before that is for sure.

Like you Zeke I've never "seen" that much movement

I should add, it wasn't just vertical. The shots dropped 2" low and left. This change occurred from Summer to Winter shooting...and Then back to Summer.

quote:

Not an easy question to answer, but ------:

Hodgdon IMR and Alliant all make 4350. From information gleaned the Hodgdon seems more stable than the IMR. H4350 has a commendable reputation as being temperature insensitive

i think you mean IMR, HODGDON, & ACCURATE MAKE 4350.. ALLIANT makes RL-17 but they are real close in burn rate tho..

I know that temp sensitive powders exist, I use them and have experienced a blown primer and stuck bolt because of it, BUT, I learnt long ago that if I worked up my loads in the hottest part of the year, then I would never have that problem again. So far, it has worked perfectly, no more surprises since doing this.
I know longer worry about wgether a powder is temp sensitive or not. I still use RE25 for 1000yrd comp in my 300WM, it's the most accurate powder in my rifle.

Cheers.

quote:

Originally posted by vines:

quote:

Not an easy question to answer, but ------:

Hodgdon IMR and Alliant all make 4350. From information gleaned the Hodgdon seems more stable than the IMR. H4350 has a commendable reputation as being temperature insensitive

i think you mean IMR, HODGDON, & ACCURATE MAKE 4350.. ALLIANT makes RL-17 but they are real close in burn rate tho..

Right on Bro:

That's a Gotcha

O'ops my inadvertent mistake.

Hodgdon H4350 does rank 117 on one of my burn charts and Alliant Reloader 17 #118.

Thanks for correcting the error.

I like that !

Accurate Arms 4350 ranks #119.

I guess I'm just lucky, I have hunted under every condition there is and never even considered this recently created problem that has raised its ugly head..

In 70 years I have never had such a problem with any powder, not even black powder, and I consider it just another created problem or a sales gimmick that some have fallen for. Most of these instances are not the powder or if so it probably the amount of powder that created the problem...I don't even recall it ever happening to Jack O'Connor or Finn Aagard or even old Elmer and he certainly would have expounded his vast knowledge on it!

I hear such particularly on the African continent, but my guess is overloads are the culprit..It gets 125 degrees in the Texas Big Bend near Presidio, Tex. and I have cooked my big bores on hot truck hoods then shot them, never could recreate the problem unless I used too hot a load to begin with..Just my take.

I have hunted from the Rockies in the Western US and Canada extensively and a little in Tanzania with rifles loaded with RL-22. I have taken game up close and out to 350 yards (my limit) and have never noticed any change in point of aim on all animals killed. Temps ranging from 100 degrees down to -26 have never affected my shooting. I will continue to use this and all powders with no worries. Good shooting.

UPDATE:
I ended up going with IMR 7977 and a Nosler 150 Ballistic tip. It shoots tiny little groups (Best was .39 and worst was .81) at 100 yards and does better than MOA out to 700 yards and every range in between!

I have no idea if I bought into the hype or if there's really something good to be had from these new powders but with 3080 fps, moderate pressure and groups like these it can't be too far off base.

I'm very pleased with the performance and if it's a bit less temp sensitive, good for me!

Wish me luck please. I'll be backpacking for bighorn sheep in Wyoming in 2 weeks. (I'm a bit too old for this kind of hunt but I've trained hard all summer to be prepared)

Thanks again for all the input.

Zeke

I was out shooting my 416 RUM, getting ready for an Africa trip, and using Re17 behind 400 SAFs, TSX, NFs, and the like.

I was using fairly hot hunting loads and I noticed absolutely no differences in velocities between 98oF ambient temperature and 64oF from previous outings.

Re17 seems to be relatively temperature insensitive at African safaris temps.

I was surprised but reassured that I'll be OK at the expected temperature ranges.

Ackley I user,
I've heard the same things about PL-17 so I sprinkled a little of that in the 280 AI also. In MY rifle the IMR 7977 shot a bit better and the velocity was higher.
RL-17 is my powder of choice for my 270 Win, 300 WSM and my 338 Win. The 338 Win load with 17 didn't fill the case like other powders but despite this it shot the best by far. My rifle also shoots the 210 Partition way better than the 225 AB. Sexy looking bullets don't always shoot the best for me.
I guess that's why internet advice should be taken with a grain of salt. Every rifle is so different.
Best of luck in Africa!!!
Zeke

Like others, I try to do my loading and work ups in summer and at 80 degrees or less.

I do this because on very rare occasions I might be shooting at up to 95 degrees I don't want to run into heat induced over pressures when I have to shoot when it's hot.

But... I have seen very cold temps cause enough speed loss that a load can be inaccurate when I hunt deer in the cold. I have hunted at -30 F, but I try to limit it to about -20. That's enough with some rifles and loads to make a difference of several inches at 100 yards and take a sub inch rifle to greater than 3 inches. Not catastrophic if you're aware of it and place shots accordingly. bad enough though that I really much prefer that I know before hand.

New powders like 4451 not only almost eliminate the problem, but I am finding the cheaper locally than older chemistries. That negates claims of more expense for new chemistry.

Most rifles, and most loads will not be that extreme. But when you see a rifle that quickly changes from normal work up groups of a couple inches to dropping sub inch with a change of only half or maybe a whole grain of powder, it's a good candidate for being touchy when very cold.

Deer season in Minnesota can present you with temps above 70 and below -20. You do have to at least think about what that does to your rifle and loads.

Testing hot/cold ammo in the Wx conditions is about as closes you can ge to seeing any significant on target results.

Several problems in the test protocol can skew your results- cold ammo slipped into a hot chamber heat rapidly, so how fast does one shoot? Accurately.

In the real world, cold ammo and a cold gun ( as in hunting) have additive variables- the bore is narrower ( coef of expansion of the barrel steel) by up to several tenths depending on caliber. This would tend to increase pressure due to resistance- and pressure is what results in velocity, all other thing being equal.

Wx conditions- denser cooler drier air at the same altitude, slows the bullet faster than warm wet air, changing POI.

As a fairly experienced LR shooter, I often see shooters fire sighters in the fall on summer zeros and behold, the target comes p with allow 7 or 8 ( 3 MOA drop) simply due to the cooler drier fall air.

In my Infantry days, I learned that M118LR ball would , by rule of thumb, change POI 1 OA for every 20 deg F in temp, and one MOA per 20% change in humidity and one MOA per1000 ft change in altitude.

Now, I know that station pressure ( the adjusted conditions based on all three variables) often level out that set of "rules of thumb".

So many variables at play the only way to really know ow your rig and ammo perform is to shoot in varying conditions at range ( 400 + yds) to learn your rigs performance
. For big game hunters at nominal ranges of less than 400yds, it probably doesn't make a big difference, but past that and at smaller targets, it surely does.