For hunting rifles, I am not one to get real hung up on the temp sensitivity thing. I simply sight in under same conditions as rifle will be used. Or close to it.

However, I have probably around 30 different powders on hand and am considering weeding some out. How clean it burns, how many guns I use it in, and yes, temp. sensitivity all influence my decisions. The latter only somewhat, but it is what has me thinking.

Through the years I have seen various powder charts listing different temp. sensitivities of various powders. These charts all seem to vary from source to source. Same with info I have read from seemingly credible sources, like people who actually work in the industry.

My question is this:

Is there any chart/info that is considered the definitive source or industry standard? One that states Powder X varies ______fps for every degree of temp. change in a given cartridge under a given temp. range.

Like I said, I have seen such charts, read info from powder company people, bullet mfgs., match shooters, etc., etc. But is there any one set of data that is widely accepted as the industry standard reference?

That's tough to produce. Temp sensitivity of the same powder will be different in 2 different cartridges. It's not stabdard across the board like a burn rate.

Even burn rate isn't standard across the board. Powders can switch burn-rates depending on the application.

Learned something new. Thanks!

MD, I was looking in Your BB of GG for 7x57 175gr. NPT loads and saw the H4350 info. Here there are only AA4350 and I4350 available. Are either one of them MOL "temp. insentive" similar to the H? I have a moose permit in NE Wa starting Nov. 1 and was just curious. Thanks-Judd

Both IMR and Accurate 4350 are pretty good in cold weather--not like H4350, but not bad either, which is true of most single-based, extruded powders.

However, temperature sensitivity is irrelevant for quite a bit of big game hunting. Moose hunting would be in that category.

That made me question the importance I've been putting on it. What ranges does temp sensitivity hit your radar?

Depends on what I'm shooting, and what effect it has. One thing most shooters don't realize is that cold not only has an effect on velocity and hence point of impact at longer ranges (which is also affected by colder air during the bullet's flight), but point of impact even at 100 yards.

If your particular rifle tends to result in significantly different POI's at 100 when working up a load, then it's likely to change POI in real cold with the SAME load. How much depends, but I've seen two big game rifles that changed POI three inches at 100 yards when shot at zero Fahrenheit after being sighted-in at 70 degrees. That amounts to a 6-inch change at 200 yards and 9 inches at 300, which can be significant even on big game.

Powders that provide similar velocities in cold as at 70 don't do this. Or at least I've never tested one that did.

Yep. Have seen many POIs be low in cold conditions. That is why I would sight in in the cold conditions or whatever conditions I plan on hunting in.

It would be a complete waste of my time to do final sight in on my muzzleloader, which I only use in December, during summer months or even right now. It would most assuredly hit low come December. I just switched scopes on it and sighted in dead on at 100 yds. Once it gets cold, will do final tweaking......

That's always a good idea--but the shifts I've seen aren't always low. They're often sideways, and in fact one of the 3-inch shifts was almost totally sideways. The load still grouped well, just in a very different place. One even landed two inches HIGHER at zero.

If you watch the movie "Ice Station Zebra", there is a moment when someone declares that an M-16 hits the same place in the cold as it does anywhere else. I remember disturbing those around me in the theater with my disagreement.

Hmmm. And you feel the side shift was due to temp. change alone?

With rifles, I always attribute low hits to the cold when it happens. I cannot ever recall blaming temp. alone for a sideways shift, but that is interesting. Usually I just have to correct elevation, not windage.

I could see it on a wooden stocked rifle before a composite, for obvious reasons. And I do tend to leave the wood at home in extreme conditions.

What I have noticed is that some of my large handguns seem to shift not only low but also sideways in the winter months. But I always blame it on something else like the scope or mounts, wind, or it got bumped, or the brutal recoil, or my shooting. Never really thought about it being the temperature. I will say that H110 is definitely not the most insensitive powder.

Interesting. I can wrap my tiny brain around cold causing low hits, but why would cold alone cause sideways shift? Steel swelling, changing harmonics? He11 IDK, haven't given the sideways thing much thought......

The more I read into things like this, the more I think I'll move to a single main hunting rifle. Much easier to keep sufficient data logs.

2muchgun,

I normally (but not always) run temperature tests in fall, because between mid-October and sometime in November the temperature in Montana will be 70 during a few afternoons, and down around zero at night. The rifles used in the tests usually (but not always) have synthetic stocks that have proven stable, along with scopes that have proven to be the same. The rifles with wood stocks are epoxy-bedded and free-floated. I don't take the test rifles out hunting during the interim between the warm and cold tests.

In fact I don't even fire them, clean them, or otherwise dick with them between the two tests. After shooting the rifles on a warm but calm afternoon, and carefully measuring and recording the target results, I put them inside well-padded soft cases so the scopes won't get bumped, then place the cases someplace safe.

When a cold night comes along I move the cased rifles and ammo into my unheated garage overnight, then leave them in the cases while transporting them to the same range, and at the range keep the rifles in a standing rack so they'll stay cold.

The tests are always made at the same range, with the same rests, over the same chronograph. In contrast to the rifles and ammo, the chronograph is kept warm, first inside my house before heading to the range, and then inside the cab of my warmed-up pickup. I also make sure the working parts and batteries of the chronograph stay warm, with different methods.

During the tests I often fire ammo loaded with different powders but the same bullet, but also test loads with different bullets, and don't fire quickly enough for the barrel to warm up significantly. Partly this is because the heat waves from even a slightly warm barrel interfere with aiming correctly through a scope on a very cold, calm day. If a barrel starts to get that warm I put the rifle in the rack, action open. They cool off very quickly at zero.

Have been doing this since 1991, and so far every handload that resulted in the same basic velocity at zero as at 70 has also shot to the same place at 100 yards, with similar accuracy. Only those that differed significantly in velocity have shifted point of impact measurably at 100 yards.

"Significantly" is defined as more than 25 fps. The same loads will often average 25 fps from string to string anyway, even when chronographed within the same hour. Only once has a load chronographed exactly the same at zero as at 70, which was pure chance, but a lot of loads with certain powders have differed less than 25 fps.

Cartridges loaded Hodgdon Extremes normally chronograph within 15 fps of their warm-test temperature, and so far have never shifted point of impact significantly at 100 yards, in a number of rifles. Cartridges loaded with Ramshot TAC and Big Game have also done very well, and a few other powders in certain applications. IMR4895 and IMR4350 have proven pretty cold-resistant in my .375 H&H with 260 and 300-grain bullets, only losing around 30-40 fps, but IMR4350 lost around 75 fps in the .30-06 with 165's.

It's not unusual for other powders to lose over 100 fps in the same temperature range, and the most I've seen is 184 fps. Sometimes the point of impact at 100 yards doesn't change, but often it does. As I've noted before, it seems to depend on whether POI also differs significantly when working up handloads with different powder charges. It also seems to be related to barrel weight. Varmint rifles with heavy barrels don't usually change POI much, if at all, which is similar to how they act when working up loads. Big game rifles with light barrels are usually the problem.

However, one of my favorite temperature-test rifles is my NULA .30-06 with a #2 Douglas, which doesn't change POI much when working up loads, probably because of the full-length barrel bedding in a very stiff synthetic stock. It's also very accurate, so any change is easily measurable. But the one load that lost 184 fps still changed POI noticeably, shifting 1.5 inches left and two inches down at 100 yards, while the rifle's primary load (using H4350) didn't shift POI at all during the same test.

So no, I don't believe the POI changes were due to scopes or mounts shifting, or walnut stocks warping.

Thanks for sharing that. I have done similar tests and like I stated, anything but a straight down drop I always blamed on something else. Now you have me wondering.

I have used IMR 4350 extensively in the cold. Mostly in 30-06 with 165s and 7mm-08 with 140 Partitions. These are 2 I used to use a lot back in the day. Both would normally shoot a bit lower in sub-freezing temps.

I would say H4350 may be the least temp. sensitive of any powder, even beating Varget, which is very good.

I have been loading R-15 in my 7-08 for maybe 5-6 years now. I sight in during November temps. I remember you saying that they changed R-15 and it may be less temp. sensitive now, or something to that effect. I am wondering if my powder was mfg. before or after said change. Any way of knowing? I guess I could call them. I have the better part of a 5 pounder of R-15 left.....

John, since H4350 is rarely available in my area now I have been researching alternatives for 120g-140g Swede.

Do you have similar temp info on other powders like R19, R23, maybe IMR 4451 that would work + are available? I had temp issues with R22 but I don’t hear much about R19 temp issues, and I have read that 19 works well for you in your swede.

Thanks,
Tim

It's the same reason POI can shift horizontally when working up loads. If the cold is enough to affect the velocity very much, then it has effectively mapped it onto what would be a different load at normal temperature. The load pings the barrel differently for lack of a better description.

That is kinda what I was thinking. I used to do all kinds of testing and such. It has been a while now. I really haven't noticed much in regards to sideways shifts in POI in rifles I use in cold temps a lot. Any changes usually involve similar groups, just lower on the target.

Except for the big bore handguns, which incorporate large chunks of frozen steel, and sometimes steel mounts, and powder that I know is temp sensitive........

stealthgoat,

RL-19 does work well in my 6.5x55--at "normal" temperatures. It's not very cold-resistant so I don't hunt with it much here in Montana.

I've been switching all my H4350 loads to IMR4451, which has been very easy. So far the Enduron powders have been very good at various temperatures.

Just started working with RL-23 this summer and have a great load worked up for my Tikka .260, but won't know how well it works in cold until I run some more tests this fall. Alliant claims it's great.

2muchgun,

The change in Reloder 15 took place around 2000, so your powder should be the more resistant version. The old stuff was pretty sad, but the improved RL-15 is pretty good. One of my primary RL-15 uses is 200-grain bullets in the .338 Winchester Magnum; in my 70/zero test the load lost 36 fps and POI at 100 yards was unchanged.

Cool. Good to know.

I just picked up some H4350 and 4895. I seem to not be able to get away from certain powders. Too many of them, actually

Why are you going away from H4350? It may be most temp insensitive powder of all. I recently read a test about it, Varget, and some new Enduron powder. The Hodgdon stuff still "won", but the IMR was still very good. I will see if I can find and post.....

H4350 availability is spotty.

That is what I figured. I was surprised to find 5 jars just now at the local gun shop...

I have a fair supply of H-4350, pick it up when I can.

From what I've read, Endurons are fairly temp stable, not quite as good as the Extremes, esp. H-4350, followed by Varget. Those two out performed their Enduron competition in a study by Bryan Litz.

Temp. sensitivity isn't that big a deal where I hunt.

DF

Here is one of the tests I was referring to. Again, figures seem to vary from test to test, but certain powders still tend to stand out:

http://precisionrifleblog.com/2016/06/19/powder-temp-stability-hodgdon-extreme-vs-imr-enduron/

Mule Deer... or others.... do you believe that load density plays a significant roll in the "temp stability" of powders? IME powders like 4064 have performed better when load densities are above about 90-95%. More powder in the case means less cold air in the case... or at least that's my simple explanation....

Also.... what about magnum primers in .308 and '06 size cases? Again, IME using mag primers tends to negate some of the issues with cold weather.

As for first question, I would say yes. Fuller cases and/or compressed loads seem to add to stability IMO.

I would say powder choice and cartridge size/ charge have more effect than what primer. But certain larger cases with certain powders, coupled with cold weather definitely call for mag primers.

Next we are going to end up having a discussion on "primer sensitivity/stability".........grin

Biggest factor is probably "shooter sensitivity/stability" in sub-zero temps.... shivering....

Yes that definitely factors in. BTDT. Usually sitting in a pile of snow holding this:

I should add, even not in the cold I think fuller cases are better. Shooting uphill, downhill, and level, the powder still moves somewhat and goes bang in a different way.....

In cowboy action shooting with low powered loads and partially filled cases, the position of the powder in the case is known to make a difference. So, it would stand to reason, with too much air space in a rifle round, that could become an issue.

BTW, it is thought by some, based on data collected, that Titegroup has the least positions sensitivity of the common CAS powders used in .38 spec, .45 Colt, etc.

DF

For Mr. Barsness. Given a comprehensive listing of powders as frex a current burn rate listing could you annotate the list into first tier powders say IMR4451, second tier say H4350 and third tier I'd guess BallC(2) say would be third tier. TAC and Varget say would I guess be first tier and likely Big Game and Hunter as well. Many would be no experience or not generally used. Tier 1 would be should be in the ideal inventory with lower tier powders being good powders but perhaps less general application and so less reason to inventory in bulk. I'm talking an ideal inventory not a minimum inventory. For a minimum inventory I could start and stop with H4895 for my guns but I'd be giving up a lot of performance to settle for getting a bullet down range.

I'm not trying to make a lot of work for you although if you can expand things to an article on powders added and dropped from the ideal inventory I'd buy the magazine (but I do anyway)

I find I'm definitely overstocked on powders I bought because I could but now relegate to what I'm calling tier 3 - following the fire code enough to scatter in 3 locations - and so under stocked on the newer Enduron and Extreme. I'll probably never use up my BallC(2) because my first choice will always be something else and the same for 30-40 pounds of other powders that are as good as they every were but maybe aren't tier 1 for my applications.

On powder position in the case see Ken Oehler's article in Shooting Times for April 2007 issue, and his story about slight of hand at workshops -

Interesting thoughts on powder being temperature sensitive. I have read some of this before and never gave it much thought. I just sighted or checked sighting on four different rifles at 80f. I'm going to mark the results and try to duplicate those results when the weather changes! At what temperature range do most start seeing the effect. I don't think we got real cold last winter, maybe -10f would that be cold enough to do my tests! I've never noticed any change while hunting, but animals don't have targets to check, as long as they go down Im good.

Clark,

Thanks for the suggestion, that might be a possibility!

I've got an assignment on temp-sensitivity for HANDLOADER on my schedule, just have to keep shooting when conditions are right.

2muchgun,

I've seen the test you provided the link for, and while it's interesting I'm far more interested in colder temperatures because of living and hunting in Montana--the reason I started testing powders in real cold years ago. I've also found that actually testing in cold (or heat), just like hunters would, is a more accurate way of determining the actual effects.

I also noticed the tests only went down to 25 degrees, which is typical of many "ammo only" tests, because that's about as cold as ammo can be frozen. But I haven't noticed all that much effect down to 25-30 degrees. Below that stuff really starts happening. I also noticed the PrecisionRifleBlog test H4350 loses 18 fps from 65 to 25, and IMR4451 loses 20 fps--essentially the same result.

Thank you, I was concerned that R19 could be similar to my previous R22 experience - very accurate & great velocity but sensitive, and my load had to be adjusted for temperature. I have enough H4350 for this year, and then I may transition to IMR4451 in the spring.
Tim

Totally agree on both counts.........

Not that this info helps me a lot, I nevertheless look forward to John's indepth testing in REAL cold weather.

From what I read, there generally seems to be lower S.D.'s in hot weather, higher S.D.'s when it's cold. It's going to be interesting to see if the 20* temp. sensitive powders really fall apart at zero or sub zero. One would think so, but you never know until you actually know...

DF

I forgot to add, wonder how much is the primer, if hotter primers will level out cold weather performance somewhat.

DF

MD,
I use Hunter exclusively for several .30-06s, using 168 BT, 180 NP, and 185 VLD. How does Hunter rate for temperature stability?





P

Not JB, obviously.

I remember hearing that TAC and Big Game are more temp stable than Hunter or Magnum. Now, how those two compare to the competition? Don't know.

My '06 does great with Big Game and I use mag primers with RL, ball powders.

DF

In Bob Hagels testing Magnum primers helped esp. in Magnum cartridges. But this varied and was not consistent across the board. I think none of the powders he tested were of the extreme or improved types. He used the freezer method so actual results may vary.

Mule Deer, of late most of my hunting has taken place in September and October in Utah so I've never much worried about powders that might be temperature sensitive, but this year will be different. I'll be hunting elk the last few days of Oct. and the fist week of November. At the 8000ft level it could get cold in northern Utah. I'll be using a .280AI, 160gr. bullet and IMR 7828. Do you have any experience with IMR 7828 ?

Haven't tested 7828 in real cold, mostly because while I've burned a bunch for handloading profiles of various rounds, have never decided to use it for the primary load in any of my rifles. But in general, the single-based IMR powders work better in cold than average. They'll lose some velocity, but exactly how much depends on the specific cartridge/bullet combination.

Thanks, John. I won't panic. I've stayed with 7828 because in my .280AI it does well and it has stayed available. But, after reading you stuff on R26, I just might try some of that after this fall.

Well, so far RL-26 is definitely interesting. I'll find out more after shooting some loads across a chronograph in real cold!

Great, I'll stay turned to this channel.

Dober did a bunch of testing back in the day and found 7828 to be pretty stable even down around 0. It was non-scientific of course.... but I trust Dober's take on a lot of stuff. You can probably find the old thread with a little creative searching.

Found it.... God bless the site-specific Google search!

Dober's "sub-zero" 7828 thread

I used to use 7828 with 160 gr bullets in a Krieger 9 twist 7 RM barrel, 24". This was back in the late 80's /early 90's when I was hunting that particular rifle a lot.

This was a "long throat" chamber that gave the 160 NPT 3100 fps. This was also about the time that we started paying attention to velocity loss with some powders.

I recall that 7828 did very well down around "0", about as cold as it ever gets here. But the combination of IMR4831/140 lost a lot of velocity down around zero.
By a lot I mean 125 fps as I recall.

Funnier yet was IMR4831 was really good in the 270 Winchester, even in very cold temps. I began to wonder if load density had any effect on velocity loss in cold weather.

Not surprised at what Dober saw.

I don't know if load density has anything to do with it or not, but the specific cartridge and bullet do. And even combinations that seem "ideal" may not be as temp-resistant as others. In one of my tests, IMR4350 with 165's in the .30-06 (a classic combination) lost twice as much velocity from 70 to zero as 300-grain bullets in the .375 H&H.

The chapter on powder in my BIG BOOK OF GUN GACK contains this paragraph, which is very relevant to this thread:

"The [first] Norma Reloading Manual, published in 2004, contains a very interesting chapter on smokeless powders by Sven-Eric Johannsson of Nexplo/Bofors, a Scandinavian company that, among other products, manufactures Norma powders. Johannsson’s essay includes this statement: 'For any caliber, rifle, bullet combination it is possible to engineer a powder that shows little pressure or velocity temperature dependency, but if loaded and shot from any other caliber, rifle, bullet combination, would likely exhibit a totally different temperature-behavior profile.'"

Interesting.

I guess physics and science can take us just so far before we're suddenly into the "snake oil" realm, trying to understand internal ballistics...

DF

It is amazing I ever killed anything in the Winter when all I used was IMR4350 and IMR 4831 or RL22.Guess I was just lucky.

Amazing, isn't it?

But I believe one of those dumb-ass gun writers once commented that since 90% of deer are killed at under 200 yards, and a deer's chest is a pretty large target, using temp-resistant powders doesn't make any noticeable difference in most deer hunting.

Most powders vary less than 1 fps per degree in most cases, IME. But there are some that are worse.

The 7828 mentioned earlier would probably lose about 75 fps if sited in around 75-80* and hunted with in 25-30*. I can't prove it, but I bet I am real close.....

I'm too lazy to go back and check each post, but if I am correct, this has gone on this long without the word "ambient" being uselessly used. I am both impressed and amazed. (Good thread, by the way.)

I wish we could know the exact powder that was developed for each of those cartridges that would result in little variation. Then I could just use that powder in that cartridge.

Bob can correct me if I'm wrong, but IIRC, 7828 was formulated for the 7RM.

DF

I wonder what percent of folks have actually missed a critter due to temperature insensitivity? A writers topic for most I suspect.

Loony stuff, Ed...

You of all people should understand...

It doesn't have to be practical or make a lot of sense...

Just sayin'

DF

DF: No correction required. It's my understanding as well.

I also think it as used in the 264 Win Mag which came a few years earlier. But I know it was used in the 7RM before it was available to handloaders.

It was few years before I tried it in the 270 Winchester and found that the top loads and velocities were similar to the WW II H4831. I thought that was interesting but not surprising I guess.

Frankly, I don't know why I'm so concerned about how temperature sensitive 7828 is because if it gets cold enough to have a real effect on my ammo I'm likely to have another cup of coffee and stay closer to the fire/heater.

Dober's thread would about settle the issue for me. Too bad he doesn't post here much any more; that's a big loss.

I look forward to JB's results, although sub zero doesn't affect me, I'll be by the fire when it's that cold...

Interesting, nonetheless; Loony stuff for sure.

I find it interesting how a powder specifically formulated for a certain round performs better than that same powder in another round.

And, pressure curve characteristics must play into the scenario. I found very sharp velocity nodes with Vv-165 in my 6.5-284, not so much with RL-17. I think that may be yet another factor among the many variables.

DF

Bob,

IMR7828 was originally formulated specifically for the 7mm Remington Magnum by DuPont, which originally developed IMR powders before World War Two. At the time 7828 was by far the slowest-burning IMR powder but wasn't released to the public in canister form for a number of years. I dunno why, but perhaps it was because relatively little was used by ammo factories, possibly only by Remington (DuPont purchased 60% of Remington in the 1930's).

As a result it took a while to end up with sufficient, slightly different manufacturing lots to be able to blend a consistent product for handloaders. Plus, at the time there wasn't nearly as much demand for a handloading powder slower than the original, mil-surp H4831, which was available for over a decade after the 7mm Remington Magnum appeared.

And, some of those early loads were pretty "frisky" before they put the cap on 7RM pressure.

DF

Two years ago I was shooting a .270 Wby with 140 grain TSX's over 71 grains of RL 22. The temperature was -16 F.

The shot was a bit over 200 yards if I remember right. I dialed the scope in for the exact distance. Three shots in a row all went low, right under his brisket. Luckily, he was more interested in the doe next to him than the bullets going past him.

I had to dig through three layers of clothes to get to my spare ammo, which was basically right next to my skin. I dropped on one warm round in and promptly blew his heart out. The cold rounds had to be hitting at least 8-9 inches low.

I would be interested in knowing at what temp you sighted in......

I missed a couple coyotes one morning with the 6.5x47 in sub-zero temps... ranges were 350-450 yards. That gun was an absolute hammer at that range... and I had no idea what had happened. I ran to my "range" and threw up a 100 yard target to check my zero. The gun was shooting about 2" groups to relatively the point of aim. Frustrated as hell... I drove home and threw the gun (literally) into the closet where it sat for a month or so, untouched. When I did finally forgive it... the first group is shot was about 1/2" dead in the middle of the 1" dot... but the temp was about 40 degrees.

The charge was 42 grains of H4350 under a 130 Berger... though I blame the small rifle primer more than the powder in that instance. That gun went down the road shortly thereafter... can't have a fun that isn't capable of cold-weather coyote duty.

Very interesting!

Elmer Keith, who lived for most of his childhood and graduated from high school about 20 miles from where I live, hunted a lot in really cold weather. I remember reading one piece of his advice: When shooting beyond 200 yards in real cold, hold for an extra 100 yards or range, to compensate both for slower muzzle velocities and the effect of denser air on the bullet's flight. But that was back before laser rangefinders and "temp-resistant" powders.

Back when I first started hunting predators in winter, my main rifle was a .220 Swift loaded with IMR4350 and 60-grain Nosler Solid Bases. That was also long before laser rangefinders, but I acquired a good idea of range by using the scope reticle, and wasn't too bad with the rifle on coyotes and foxes out to pretty long range.

I found Keith's advice pretty sound back then, but there are all sorts of factors that can affect cold-weather shooting, and primers can indeed be one. The big trouble I've encountered isn't with loads these days, because I live where they can be tested thoroughly during actual winter conditions. The big problem is the many people who want an answer about what works WITHOUT such testing. In general, Hodgdon Extremes and a few other powders work well in real cold, but the best option, always, is to pre-test to see what happens. Nothing beats proving rather than guessing.

Calling "quad" taken on a day with a -25F morning temperature. the farthest shot was only a tad over 200 meters, and not enough to cause a low impact(not missing the vitals) with a 130gr Berger VLD at 3000fps.

Cold, dense air will inflict more drag on a bullet, especially in very severe temps, even when your muzzle velocity is close to the same in warmer temps. Like John said, the best way to really find out is to brave the elements and go test your loads in those conditions.

No doubt temperature sensitivity is a complex issue. How do you identify the contributions to velocity change? Primer, powder, barrel dimensions, etc. I've decided to just shoot the loads in question, out of the rifle, in as close of conditions as I can get to hunting. What I have not done, and need to, is verify POI at a meaningful distance.

Having shot a handful of powders, I have a sense for how each powder will vary. Hodgdon extremes, 8208 are good, most ball powders are varying degrees of bad in my rifles with TAC the worst losing between 70-100 FPS for three different load/bullet combos. Most other ball powders were 40-60. 8208 was great being +12, +12, -4, and -6 for four different loads/bullets. Limited data, but enough to give me a sense.

Having looked into it, I'm still shooting LVR this elk season. I don't find elk very far away, so I don't think 40-60FPS will really matter.

John - yet more evidence of your knowledge - thanks for carrying the banner.

Thanks, but no credit to me! That's just how my family spoke.

Should note that I've also seen the effects of warmer temperatures on point of impact. In the 1990's I went on a plains-game trip to Africa with a .338 Winchester Magnum, and had worked up two loads, one with the 250-grain Nosler Partition for eland (one of the major points of the safari) and one with 200-grain Nosler Ballistic Tips for everything else, especially at longer ranges.

Taking two loads may seem like a bad idea, but both loads shot to the same point of impact and I knew the 250 would work on everything too, so would start with it until taking an eland, then would switch to the 200's. Got lucky and took a good eland the second day of the hunt, so switched to the 200's.

However, it soon became obvious something weird was going on. The load had been very accurate back in Montana at temperatures around 70, which supposedly wouldn't be all that different from temperatures in Namibia during the winter solstice south of the equator. But a few days were close to 90, and some of the bullets landed noticeably higher than they should have. So I switched back to the 250's, which were loaded with H4831SC, which solved that problem.

Back home in Montana it was now the peak of summer, so I started shooting in warmer temperatures. The rifle was sighted-in 2 inches high at 100 yards at 70 degrees, but while the 250-grain load still shot to the same place at 90 degrees, the 200-grain load would shoot up to 5 inches above point of aim--about 7 inches high at 150-250 yards. This probably caused one mysterious miss, but mostly I ended up spining animals when aiming for the middle of the chest.

The powder charge used in the 200-grain load was 65 grains of Reloder 15, which shot spectacularly at 70 degrees. But this was before Alliant modified the formula to be more temperature-resistant, due to RL-15 being considered by the U.S. military. The formula was changed around 2000 or 2001, and RL-15 became much less temperature-sensitive. The load still shot great in my .338, but POI didn't vary in temperatures up to 90 or down to zero, where it only lost 30-some fps.

I better learn to test even over a temperature range I consider from shirtsleeve to shirtsleeve. Makes it harder to check scopes when traveling if the external ballistics have to be checked too.

It's easy to snark about this isn't cold, West Yellowstone on a cold day is cold and this isn't hot, well over 100 degrees F. at 3 in the morning is hot weather and I've done both but cold or hot for powder can be a different thing.

The Norma Gun Bugs Guide as I recall claimed the 5 Norma canister powders then sold in the United States were all qualified for aircraft cannon but I think I took that to mean more than gets the bullet out the barrel.

Early fall, so probably in the 60's - 70's.

I had something similar happen using W-760 out of a 7mm-08 years ago, but the difference was about 6-8 inches at closer to 300 yards.

I used 760 for a while in one of my first Ultra Light Arms rifles, a 7x57, where it was very accurate with 140-grain Ballistic Tips. In fact, in warmer weather (around 85-90) the load was even more accurate, but in cold weather it wasn't so good, though not significantly different than many extruded powders were back then.