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My very limited temp test of RL17 consisting of two shots at 70deg, and two at just under 20, after sitting out all night with temps to 8, showed no change in velocity. Measured with a Magnetospeed on a 338-06. Other powders lost up to 100fps.
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brayhaven-
I'll be nice and polite.
I believe you and your tests report.
I respectfully suggest that you try to duplicate those same tests using 'premium' bullets. I think you'll find 'different' results.
Jerry Thanks for your civility Jerry.:) You might be right, but the only premium bullets back then were the old Barnes pure copper & lead & the Nos partition. We could have used FMJ I guess, but that wasn't the point. Karamojo Bell killed over 900 elephants with the 7x57.. Jack O'connor said the (American) hunting community would be no worse off if the only caliber available was the .270 & the only loading the 130 grain. As a gunsmith, I've seen a lot of damage to guns: some from experimentation, but mostly carelessness. I've just never seen a need to jack up pressures over 60K. There was a post regarding the Ackley improved calibers and pressure. But it's very different. The case design with minimum body taper allowed that to some extent by transferring breech pressure to chamber pressure. And the case head was still the limiting factor.
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Campfire Kahuna
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prm,
One of the problems with "temperature sensitivity" is that there really isn't a firm definition, and to a certain extent it's dependent on the cartridge and load. A chapter in the Norma manual mentions this, essentially stating that a very temp-resistant powder can be developed for any specific cartridge/bullet combination. But the same powder may not be particularly temp-resistant in another cartridge/bullet combination.
I've seen this many times during my load testing at different temperatures. Among the more cold-resistant results of what might be termed "standard" powders occurred with IMR4350. A load with IMR4350 and a 300-grain bullets in the .375 H&H lost only 38 fps from 70 to zero, but during the very same test, IMR4350 lost 74 fps in a .30-06 load with 165's.
During the same test, however, two loads with Hodgdon Extreme powders lost less than 15 fps in the 7x57 and .338 Winchester--which is less than the normal variation between two strings of chronographed shots recorded at the same temperature. This is what I've generally seen with Extremes in a wide range of cartridge/bullets combinations.
But the truth is that powders claimed to be temperature resistant just have a broader "comfort zone" than other powders. Another truth is that NO powder will produce the same velocity, even in loads in its comfort zone, at temperatures from zero to 100 degrees. And powders that resist cold may not do so well in heat, though in general there's an overall resistance to both cold and heat in the most effective powders.
The most temperature-sensitive powders I've tested, both in cold and heat, are those developed to produce higher-than-average velocities in specific applications, even inside their comfort zones.
Another factor is that large velocity variations often don't show up until temperatures get really cold or really hot. Almost any powder will be pretty consistent between about 35-40 and 80-85. Some that are more temp-resistant will extend that range a little, but it takes a really temp-resistant powder to minimize velocity variations in a wide range of cartridge/bullet combinations from zero to 100.
My own tests of RL-17 in various loads indicate its temp-resistance is better than average, but not outstanding.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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Campfire Kahuna
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brayhaven,
Ackley's tests were deeply flawed. More recent tests, with better testing equipment (including pressure-sensitive taper used in a number of industrial applications) indicate case shape has zero effect on "breech pressure"--the pressure on the bolt face. This is because at pressures above .30-30 level cartridges brass stretches, and overall chamber pressure is distributed equally to the bolt face. Extremely heavy-walled cases might prevent this, but not many commercial cases are heavy enough to prevent stretching at 60,000 PSI.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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Campfire 'Bwana
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John those are really good points and one reason a lot of this temp sensitivity business will drive us crazy chasing it. And then when you change lots of powders and see the variations it's sometimes hard to evaluate what you're looking at and what's causing the variations. Frieds and I are now seeing lot to lot changes in H1000 in the 7mm Mashburn; I noticed it about a year ago as my old lot dwindled and I tried some new stuff. The old lot gave 100 fps more velocity. They are noticing the same thing so I don't think it's temperature since I've shot the new stuff side by side against my older ammo. It's hard to be a backyard lab on this stuff. I remember a ways back when I noticed this temp stability business, I recall IMR4831 showed more velocity loss in the 7 Rem Mag with 140 gr bullets than it did in the 270 with 130's. This was pretty consistent over maybe a couple of winters, since I did a lot of winter chrongraphing back then. I often wondered if load density had an effect on it, I also recall that 7828 did pretty well in the 7 Rem Mag with 160's going from winter back to summer temps, It seemed more consistent than either IMR4831 or IMR4350, but like you say it might have been the load and cartridge. What you have observed is the reason I will replace older powders with the newer temp resistant powders but not until I burn up the old stuff... 
The 280 Remington is overbore.
The 7 Rem Mag is over bore.
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I respectfully suggest that you try to duplicate those same tests using 'premium' bullets. I think you'll find 'different' results.
Jerry Thanks for your civility Jerry.:) You might be right, but the only premium bullets *** back then*** were the old Barnes pure copper & lead & the Nos partition. "back then" and 'Barnes & N P' tells me it has been a long time SINCE those tests. I encourage you to RE do the tests w/todays Modern Bullets. It makes sense to me that c/c bullets expand much more at HI vel and therefore reduces penetration. We have a few more Premium Bullets today that will withstand HI vel and penetrate MORE. Jerry
jwall- *** 3100 guy***
A Flat Trajectory is Never a Handicap
Speed is Trajectory's Friend !!
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My own tests of RL-17 in various loads indicate its temp-resistance is better than average, but not outstanding.
What cartridges did you test RL-17 in?
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Campfire Kahuna
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I would have to look at my notes but have tried it in at least a dozen, though not always in one of my extreme temperature tests. But I do note temperature as part of any range session, and have noticed velocity variations at temps from 35-40 to 80-90 in some cartridge/bullet combos.
Am planning extensive shooting at both summer and winter temps over the rest of 2016 with a bunch of newer powders advertised as temp-resistant for a magazine article. Will know more as those tests take place.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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My very limited temp test of RL17 consisting of two shots at 70deg, and two at just under 20, after sitting out all night with temps to 8, showed no change in velocity. Measured with a Magnetospeed on a 338-06. Other powders lost up to 100fps. I have gotten the same results for RL17 in the 6.5CM, 7mm-08, 7mm-08AI and 30-06 - zero velocity variation from ~25F to ~65F. Same loads do start picking up velocity as the temperatures go over 70. Have seen 25-50fps from ~65F to 95F. David
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Campfire Outfitter
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prm,
One of the problems with "temperature sensitivity" is that there really isn't a firm definition, and to a certain extent it's dependent on the cartridge and load. A chapter in the Norma manual mentions this, essentially stating that a very temp-resistant powder can be developed for any specific cartridge/bullet combination. But the same powder may not be particularly temp-resistant in another cartridge/bullet combination.
I've seen this many times during my load testing at different temperatures. Among the more cold-resistant results of what might be termed "standard" powders occurred with IMR4350. A load with IMR4350 and a 300-grain bullets in the .375 H&H lost only 38 fps from 70 to zero, but during the very same test, IMR4350 lost 74 fps in a .30-06 load with 165's.
During the same test, however, two loads with Hodgdon Extreme powders lost less than 15 fps in the 7x57 and .338 Winchester--which is less than the normal variation between two strings of chronographed shots recorded at the same temperature. This is what I've generally seen with Extremes in a wide range of cartridge/bullets combinations.
But the truth is that powders claimed to be temperature resistant just have a broader "comfort zone" than other powders. Another truth is that NO powder will produce the same velocity, even in loads in its comfort zone, at temperatures from zero to 100 degrees. And powders that resist cold may not do so well in heat, though in general there's an overall resistance to both cold and heat in the most effective powders.
The most temperature-sensitive powders I've tested, both in cold and heat, are those developed to produce higher-than-average velocities in specific applications, even inside their comfort zones.
Another factor is that large velocity variations often don't show up until temperatures get really cold or really hot. Almost any powder will be pretty consistent between about 35-40 and 80-85. Some that are more temp-resistant will extend that range a little, but it takes a really temp-resistant powder to minimize velocity variations in a wide range of cartridge/bullet combinations from zero to 100.
My own tests of RL-17 in various loads indicate its temp-resistance is better than average, but not outstanding.
John, I completely agree there is little definition. The powder is only one variable. Primers, barrels are also likely influential to some degree. I will admit I don't understand the physics/chemistry of how a powder could have little change across temps in one cartridge and significant change in another. A given powder is applied only in similar expansion ratio situations and would, I think, react similarly. I certainly can't refute Norma or anyone else though. Sure be fun to test though! I need more rifles. What I did is nothing more than collect a few data points. Certainly not enough to be definitive. My goal was to simply have a better understanding how velocity would change from an indoor range to a typical winter hunting situation. Nothing more. Having said that, it told me enough regarding how my loads perform in my rifles. It was very consistent in that ball powders lost a "significant" (to me) amount of velocity while the extruded powders lost very little if any. Off the top of my head, 2000MR, TAC, and LVR lost 80-100+ FPS, while 8208, RL-17, H4350, and IMR4451 lost anywhere from 0-25 FPS. Again, only four shots, take it for what it's worth.
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IIRC, Denton found that barrel temp is more critical than powder temp when determining PSI/Velocity.
When posters offer their own findings here, how are you controlling for barrel temp especially while firing multiple shots to obtain sufficient samples to be statistically significant?
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Campfire Kahuna
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prm,
Here's the quote from THE BIG BOOK OF GUN GACK, in the powder chapter:
The 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.” Put in simpler terms, a powder’s temperature-resistance depends on the cartridge and bullet used.
TAC was originally designed as a military powder, specifically for the 5.56x45 and 7.62x51 NATO cartridges, where the same powders tend to work. I was informed it was very temp-stable, and the first time I cold-tested it at right around zero Fahrenheit, the same load averaged EXACTLY the same velocity as it did at 70 degrees--which has to be coincidence, since two strings of the same load almost never average exactly the same even when chronographed within minutes of each other. But it was pretty impressive.
During the same test, a load with 150-grain bullets in the .30-06, using Big Game powder, chronographed 21 fps than it did at 70, but I've also chronographed the Big Game load I use in the 9.3x62 with 286-grain bullets. It's been pretty consistent, though I haven't chronographed it in cold down to zero.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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Thanks. I believe you! I don't understand the interior ballistics that make it so, but I don't understand a lot of things. I'll load some TAC on the .308 Win and see what happens next winter.
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I no longer shoot jacketed bullets in WW2 rifles with some exceptions. When I started shooting they were not that old, now they are. Hmmm. My first 06 was a Springfield 03-A3. Dad bought that as surplus for about $9 I think. It wasn't mush more than 20 years old then. The worst powder load combination was the slowest Winchester ball powder at that time in a 300 Win Mag. Shooting text book loads one hot summer's day- Ft Peck MT. Sighting in the rifle and checking the loads 100+ degrees. First shot, I couldn't see the hole in the target, I needed the exercise so I walked down range (100 yards) and back. That first shot showed no sign off excess pressure. The second shot the bolt lifted a little harder. I looked at the base of the cartridge. The primer showed some pressure. No shiny brass or anything. I walked down range and back. The next shot, powder in my face, the bolt was almost frozen in place. I finally got the bolt open. the case could be reused again with a shotgun primer perhaps. No damage to the rifle so...  No I didn't shoot another load. I pulled all the bullets. That was the only pound of that powder and I've never bought it again.
Last edited by Bugger; 05/05/16.
I prefer classic.
Semper Fi
I used to run with the hare. Now I'm envious of the tortoise and I do my own stunts but rarely intentionally
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Campfire Ranger
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![[Linked Image]](http://i757.photobucket.com/albums/xx220/ClarkM/DSCF0032bulletpinch308brass243chambercropped.jpg) I have been overloading dozens of cartridges for 15 years to see what happens. This pic is from 9-12-2003. 1) I would have bet money I could not get as much velocity in 270 150 gr as I did with Re17. But once I include the temp sensitivity into my derating calculation for a useful load, Re17 is down with the rest of the powders and trajectory that changes with temp. So I never used Re17 for anything after that, due to my wide temperature range hunting. Does this make anyone think of H 205 ? I have used H 205 and still have 1 lb. I loved it in 30-06 w/165 gr bullets. I never had a problem but others did and H discontinued its production. Jerry
jwall- *** 3100 guy***
A Flat Trajectory is Never a Handicap
Speed is Trajectory's Friend !!
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Campfire Kahuna
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carbon12,
I missed your post about Denton's conclusion. In my experience he's correct, the main reason I test both ammo and rifle when the ambient outdoor temperature is about where I want it, whether zero or 100 Fahrenheit.
Far too many gun writers have chronographed and target-tested ammo that's been heated or chilled, rather than reproducing actual field conditions--which is what we're interested in.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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IIRC, Denton found that barrel temp is more critical than powder temp when determining PSI/Velocity.
When posters offer their own findings here, how are you controlling for barrel temp especially while firing multiple shots to obtain sufficient samples to be statistically significant? I did not do anything special other than let barrel cool between shots (admittedly cool, not cold) and I did not allow the new round to sit long. Basically chambered and fired within one second or so. No aiming.
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Campfire Kahuna
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No aiming?
I also test for is accuracy and point-of-impact changes. One of the big negatives of temp-sensitive powders is significant POI changes. Have seen as much as 3" at 100 yards.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck
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OP
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Is there a list of powders that are not temperature sensitive? I imagine the list grows but a current list would be appreciated.
I prefer classic.
Semper Fi
I used to run with the hare. Now I'm envious of the tortoise and I do my own stunts but rarely intentionally
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brayhaven,
Ackley's tests were deeply flawed. More recent tests, with better testing equipment (including pressure-sensitive taper used in a number of industrial applications) indicate case shape has zero effect on "breech pressure"--the pressure on the bolt face. This is because at pressures above .30-30 level cartridges brass stretches, and overall chamber pressure is distributed equally to the bolt face. Extremely heavy-walled cases might prevent this, but not many commercial cases are heavy enough to prevent stretching at 60,000 PSI. I would respectfully disagree with those conclusions. My 45 years gunsmithing & shooting show the opposite. In fact with a dry chamber and cartridge case, there is very little pressure on the bolt face. Proof of this is easily seen in rifles with excess headspace. If the case & chamber are not oiled, the primer simply backs out against the bolt face. It's one reason headspace is not as important in regards to safety as some would have us believe. If the case were hitting the bolt face, the primer would be flush. Stretching occurs in the area just ahead of the case head and forward. The minimum body taper reduces the likelihood of thrust in a clean oiled environment. And the 30/30 AI loads he used were much higher pressures than factory. He always offered to shoot the 30/30 AI in a 94 win with the locking lugs removed to prove his point. Never heard of anyone taking him up on it though :o).
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