Temperature Insensitive Powders for Hunting up North

[Tawaliga]

I am working up loads to take up to northern Canada this fall to shoot game within 400 yards and am wondering if any powders should be preferred over the others due to temperature swings.

I live in Florida and am shooting in the 90s right now, but I might be hunting in 30 degrees.

The specific powders I have now are IMR 4353, IMR 4831 which I have had success with in working up loads down here.

I am wondering if I should be using something else like Reloader powders.....

Thanks for any feedback

[fightthenoise01]

What cartridge are you loading? I worked up loads for both 6.5 Creedmoor and .280 Rem with IMR 4451 in Texas (hot AF) and hunted those loads in northern Minnesota at near zero temps. Both loads confirmed zero upon arrival and I’ve taken game with both. So the Enduron line is good to go, at least from my anecdotal evidence.


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[Tawaliga]

300 win mag

[RC20]

The issue tends to go the other way. Load at colder temps and ok and hotter temps it goes over pressure.

Unless you loose enough velocity to fall out of a real accuracy node its not an issue.

You can play with it and drop half a grain off your good load(s) and see how they do.

[Tawaliga]

RC20, that makes alot of sense. Thank you

[RC20]

Sa'll right. We shoot /developed loads at some pretty cold temps so we have to watch it as it goes the other way.

Even temp stable is relative. Its better but not completely stable so it still shifts, just not as much.

So if one shifts 100 fps between say 30 and 90, the stable ones might only shift 40.

Not 100% and 6o fps may well not be enough to do anything in regards to a hunting load.

Unclenick may weigh in, I am winging values, it might be closer than that and less impact.

Bench rest might very well be a possible issue.

[Bfglowkey]

A fellow Canadian hunter...nice. I am down in San Antonio ( that's Texan for Devils Anus Hot) and was concerned about the same thing as I will be headed up to the great northern frontier shortly once my last few doctor follow ups are done and I can press on out freshly retired. A friendly chap gave me a tip that worked pretty well:
Develop your load as normal and take 5 rounds and put them in a ziplock bag or food vacuuming thingies....once all the air is out place it in the freezer for a spell and put them in a cooler or something ( I tossed it in a yeti super tumbler with ice ) brought it to the range and fired them cold bore over a chrono.....lost a very little velocity ( both in 308 and 6.5 Creedmoor) and POI was roughly the same.
Trick my dad uses is he only loads 2 rounds ...goes stalking and after a spell he replaces those rounds with 2 from his warm inner pouch so that he never has them cold soaked too long.

[Road_Clam]

I shoot in New England year round. I have some experiences observing temp instability, specifically with Win 748. I love this powder for 308 bolt and 5.56 gas gun AR but I do notice some ambient temperature pressure variances when attempting precision 308 bolt. Pressures will be higher in July, and lower in October. I've measured as much as 70 fps spread.

[Colorado Redneck]

Got this from another forum:
* represents degrees F

HS-6 1.21fps per *
H110/W296 1.24 fps per *
Imr4227 1.17fps per *
Lil' Gun 1.31 fps per *
RL10x .71 fps per*
Benchmark .44 fps per *
Imr3031 .73 fps per *
Imr8208xbr .59 fps per *
H4895 .23 fps per *
Alliant Varmint pro .89 fps per *
Alliant AR comp .77 fps per *
Varget .19 fps per *
W748 1.32 fps per *
Imr4064 .53 fps per *
Ramshot Tac .91 fps per *
Imr4895 .87 fps per *
AA4064 1.11 fps per *
AA2520 .98 fps per *
RL15 1.52 fps per * from 50* and up
PP2000MR .99 fps per *
Imr4320 1.32 fps per *
Ramshot Biggame .98 fps per *
H380 1.44 fps per *
VV N150 1.08 fps per *
H414/W760 1.42 fps per *
Imr4350 .64 fps per *
AA4350 .47 fps per *
H4350 .29 fps per *
RL17 1.42 fps per *
Hybrid 100v .78 fps per *
RL19 1.61 fps per *
VV N160 1.24 fps per *
Imr4831 1.19 fps per *
Ramshot Hunter .86 fps per *
H4831 .36 fps per *
RL22 1.71 fps per *
Imr7828 1.36 fps per *
Magpro 1.01 fps per *
H1000 .21 fps per *
RL25 1.59 fps per *
Ramshot Magnum .87 fps per *
Retumbo .49 fps per *

[Bfglowkey]

I am guessing those are the expected FPS loss/gain per degree?

[std7mag]

Yes, see the asreik.
Looks like Varget and H1000 are your friends, according to the chart.

[Road_Clam]

It's no secret that Varget is an outstanding powder as far as stability over a wide span of temps. Still love my W748 ball powder i've just learned my different come ups depending on the ambient air temps.

[F. Guffey]

Load here and shoot there? If I wanted to know what my ammo was going to do there and I had to develop here I would use a cooler to transport my ammo to the range after I cooled the ammo in the freezer.

And then there is the Farmers Almanac. It reminds me of Ice fishing, you 'gotta' keep your worms warm.

F. Guffey

[Grey_Lion]

more-so than the powder you're firing, I believe a more important factor might be the lubricant you use in the firearm to ensure smooth action of the moving parts. You might want to spend some time studying that piece of it. Gun oils you use in FL will tend to seize up on you and stick in a Canadian fall.

[FrankenMauser]

If you believe reloading is an exact science, or cannot do your own testing in cold weather, then pick a powder 'known' to be "insensitive" and run with it.

Personally, I'd pick some candidates and figure out how to start testing across the temperature range the loads may see.

Temp sensitivity of smokeless powders
Got this from another forum:
* represents degrees F

I'd be curious what the test conditions, procedure, and cartridge(s) were for that list.

I've done some temp sensitivity testing and found that different cartridge/bullet/primer/powder combinations can change the way powders perform at different temperatures. Running at different pressure levels can change the way powders behave, as well.

Without listing the specifics of the loads tested for each powder in that list, I wouldn't feel confident in nailing them down to an exact fps change.
A powder that seems temp sensitive in .243 Win might not show any sensitivity in .358 Win or .30-06, but then goes wonky again in .300 WM. You just won't know unless you test.



For example...
In my search for "one load to rule them all", I tested Ramshot Hunter [0.86/* above], H4350 [0.29/*] and Reloder 19 [1.61/*] (and half a dozen other powders), head-to-head from sub-freezing to 100+ F, in .270 Win.
Ramshot Hunter and H4350 lost, because they were incredibly insensitive and very consistent within a small window (or away from the extremes) ... but went to crap outside of their respective 'sweet spot'.

Reloder 19, was theoretically the most "temperature sensitive" powder on my list, but beat Hunter, H4350, and all others. Within small windows (20 to 40 degrees wide) or away from the extremes, most other powders outperformed the RL-19 by a notable margin. But when stepping back and looking at the entire data set, RL-19 was the most consistent and predictable across the entire temperature range - for velocity, point of impact, and group size.

On paper, Reloder 19 was the biggest loser. But with that cartridge/bullet/primer/powder combination, it defied conventional wisdom and all popular theory.

Internal ballistics are not as cut-and-dry as most people want to believe.

[Unclenick]

The problem with that table is each loss rate is typically applicable to just one cartridge and bullet weight combination and can be different in another. Varget, for example, does fairly well in .308 but no better than a lot of other powders in .223. Road Clam's description of 748 is another example of how this can change.

Denton Bramwell had a good article on temperature sensitivity in the now-defunct Varmint Hunter magazine. RSI keeps a copy up, so you can read it here. The issue turns out to be that barrel/chamber temperature has more effect than ambient temperature, and barrel temperatures can get well outside the stabilized temperature range. So the temperature compensation can work very well in a cold barrel, which is what most stalking hunters are interested in, but a varmint hunter running a string may be disappointed. if you are running a string of follow-up shots they had better be at a rapid enough pace that heat can't affect the primer or the powder much before you get to fire them. Don't let a cartridge sit in a warm chamber for long. How long you may do this will depend on the powder, bullet and the physical size of the cartridge, with powder in larger cartridges taking longer to get warm, though the primers in all of them can heat pretty rapidly and they have temperature sensitivity, too.

Another factor is that powder grain design can affect sensitivity to both temperature and pressure. 25 years ago, Dave Milosovich published an experiment in the Precision Shooting Reloading Guide in which he loaded 180 grain bullets in the .308 Winchester to specific velocities using IMR4895 and IMR4064. The grain geometries of those two powders are different, but the chemistries are the same so they have the same total energy content per grain of weight, which is important to the experiment's comparison. The 2200 fps load needed more 4895 than 4064, making it look like the 4064 was the faster burning powder. At 2300 fps the difference shrank. At 2400 fps the charge weights were the same. At 2500 fps the 4895 charge was smaller as if the burn rates had reversed. But there is another way to look at it. That is simply that the number of feet per second gained with each grain of powder was lower for 4064 because its burn rate is faster at lower temperatures and pressure (bigger perforations in the grains) but it changes less with increased temperature and pressure. In effect, it is less temperature sensitive just because of the geometry of the grain. This was demonstrated during the Irag war. The old M118LR load using a military version (flash suppressant added) of Reloader 15 was known to develop pressure problems in the desert heat. When Federal developed the Mk.316 mod.0 round for the M24 sniper system, even though they were owned by ATK who also owned RE15 maker Alliant at the time, they went with special flash-suppressed IMR4064 because it got them out of that problem. I think this explains why many have preferred 4064 in the past for target loads.

Varget was originally designed to compete with IMR4064. If you look at different loads of it in Hodgdon's data you will find with some it produces even less change in fps/grain between the starting load and maximum load than 4064 does. However, that also means you sometimes can't use enough to get to hit certain velocities at certain load densities in some cartridge and bullet combinations, which is, I believe, why some people can't seem to find a great load with it while others find it to be the cat's meow. There are trade-offs in everything.

So, back to finding a good 300 Win Mag load. If you are hunting in a manner that means you will shoot your main shot from a cold barrel, then all the temperature compensated powders should help you. The experiment with chilled rounds is a good one as long as the barrel isn't hot when you chamber them. Note that primer energy can drop in the cold so you may not get identical performance from your warm and cold ambient loads, but it should be at least good. Ice will do just fine if you are not expecting to shoot at below freezing temperatures. You can buy PCM in containers for ice cream dispensing boxes that freeze at -6°F, +3°F, and +10°F. Unless you have a special cold freezer you would likely have to use dry ice (-109°F) to freeze both, then remove them from the dry ice and leave them out until the temperature rises to the thaw point and stalls (have started to thaw), then put them in an insulated box with the cartridges.

Let your barrel cool completely between shots. Some long-range Benchrest shooters (I'm using the capital B to distinguish the sport of printing really tiny groups from merely shooting any gun off bags on a bench) have small blowers they use to speed up barrel cooling. The better of these are basically the little battery-operated squirrel cage blowers (higher head pressure than most pancake fans) funneled into the breech to blow cooling air through the bore). My own approach, though, is to clean after every shot with a water-based bore cleaner. I pull the bolt and pump spray Bore Tech Eliminators into the chamber with the muzzle down and watch it run down to the muzzle, patch it, then pump again and let it sit five minutes, then run a wet patch followed by two dry ones. I find that and the time it takes does the job of cooling after a single shot fairly well. I figure a hunting load is likely to be fired from a clean, cold barrel, so I want to know where that combination prints.

[Road_Clam]

It's interesting that RL15 ranks higher on the instability table, as it's my second choice right behind Varget for shooting High Power with the 77 SMK / Nosler CC's . Never spent a lot of time testing velocities with RL15, 24 gr is my magic number and it's an MOA load in my service rifle. Me personally not going to get my panties all bunched up over the above chart. I was successful with a wide and diverse powder selection prior to reading the chart, and i'll be successful after reading the chart ! LOL

[Colorado Redneck]

I have looked on various shooting forums and haven't been able to locate the post where that chart came from. Of the little bit of searching I have done, it seems that each load has unique characteristics and as stated above, loading is not an exact science. I shared the chart because it appears somebody created it as a reference but how it applies in reality is a mystery. Use at your own discretion.

[mete]

Keep in mind that lubes are a major problem along with condensation. Cheap lubes and excessive amounts can gum things up easily. Some in arctic conditions will not use any lube .I would use a minimal amount of a lube designed for cold .
The arctic cabin has two rooms . One for living ,one for storing all equipment . That eliminates condensation problems .

[Unclenick]

I think Ed's Red uses ATF to be able to handle low temperatures, specifically.

[T. O'Heir]

Northern Canada is a big place. Where and when matters. And 30F isn't cold. Plus you'll be checking your sight in when you get wherever you're going anyway. The velocity isn't as important as the accuracy.
You should water seal the inside of the stock, if it's wood. Any wood sealer will do. No lube at all if the temperature is below freezing. That depends on where you're going.
"...IMR 4353..." IMR4350? That'll do. Been using it in .243 for eons. IMR4064 and either 4895 will do as well.

[std7mag]

My load development for my 7mm-08AI was conducted in 80 degree F weather.

Doe shot at 413 yards, another 1000 ft. elevation, and 18 degrees F.

Sight in, and go hunting.

Sometimes we just take this chit too far, and worry about more than we need to. KISS !!!