I constantly see on reloading forums where people talk about temperature sensitive powder. Could someone please explain to me what exactly is being referred to when this subject comes up? It always seems to be with Alliant powders when i read these post. I use lots of different powders but i also use Re22 quite often with my 25.06 and have used 15,19 and some 25 in other calibers as well. I honestly don't know if i've ever experienced this temperature sensitivity issue with this powder and am just wondering am i missing something. Are we talking about going from a really hot day of shooting to a really cold day with the same load and getting different results? Thanks! Mike
Temperature Sensitive Powder?
- Thread starter Guybo
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DrMike
Ballistician
- Nov 8, 2006
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For quite some time, armies were confronted with the situation of significant velocity changes in military ammunition when moving from one environment to another. They might train in relatively hot conditions, but when firing their weapons in colder temperatures, the velocities often dropped, and sometimes dramatically. Of course, this meant that a load developed under cold conditions could generate exceptionally high pressures when fired in hotter temperatures. Australian Defence Industries developed a series of powders that were relatively unaffected by these climatic changes. These powders are marketed in North America by Hodgdon, who advertise them as Extreme powders that give consistent burn rates under extreme conditions. These powders include H4198, H322, Benchmark, H4895, Varget, H4350, H4831 and H4831SC, H1000, Retumbo and H50BMG. All powders show differences in burn rates, and under extreme conditions the differences can be significant, especially when shooting at extended distances. In these instances, the pressure changes mean significant velocity changes which shifts the point of impact; and this shift is exaggerated the longer the distance from the muzzle. The average hunter who does not take shots over 450 yards, who isn't planning on hunting when temperatures are 110 degrees in the shade or -30 degrees, will likely not have a problem using a powder that is not one of these powders. I shoot quite a range of powders, including all the Hodgdon powders and those they market (IMR and winchester), all the Alliant powders, all the Ramshot powders, most of the VihtaVuori powders and quite a few other powders that are not commonly available. I can measure velocity differences, especially when measuring in weather that is -15 C or cooler. I don't often shoot in temperatures above 27 C, so extreme heat has not been a problem nor have I generated a great deal of data. I do take into consideration what the purpose is for a given load and what rifle it will be shot in when making recommendations. If an individual plans on hunting the mountains of Hindu Kush, I will try to work up a load in cold conditions and caution against shooting in higher temperatures, even if using Extreme powders, as there are still measurable pressure changes. Likewise, if an individual plans to hunt the Sonoran Desert in mid-summer, I will adjust the recommended load to match the rifle. The issue of temperature sensitivity doesn't seem to be a major problem for the average hunter or shooter, however.
wildgene
Handloader
- Jul 4, 2011
- 1,597
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Quote from Ramshot Powders...
"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."
...@ some point you have to decide what is "advertising hype" & what is "common sense". Using an appropriate powder & charge for the cartridge, not leaving your "super-hot varmint rounds" on the dashboard, realizing that a load sighted in for 100yds @ 800ft. elev., 80*, 80% humidity isn't going to hit where you expect it to when you shoot 800yds, @ 8000ft.elev., -8*, 8% humidity. Being "Temp. Insensitive" probably means it will be more consistent, but you're going to need a very accurate rifle, or be "shooting way out there on the Bitter Edge" to notice the difference...
"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."
...@ some point you have to decide what is "advertising hype" & what is "common sense". Using an appropriate powder & charge for the cartridge, not leaving your "super-hot varmint rounds" on the dashboard, realizing that a load sighted in for 100yds @ 800ft. elev., 80*, 80% humidity isn't going to hit where you expect it to when you shoot 800yds, @ 8000ft.elev., -8*, 8% humidity. Being "Temp. Insensitive" probably means it will be more consistent, but you're going to need a very accurate rifle, or be "shooting way out there on the Bitter Edge" to notice the difference...
- Thread starter
- #4
In my area i shoot in fairly extreme temperature swings, from 95ºF to -10ºF is not uncommon. So i have a summer load I use along with a winter load.
Even using Varget a Hodgdon Extreme powder i need to have 2 different loads.
Here is a video of a 350 yard miss, (1 of 3, all close POIs,) using my summer load of Varget in 22ºF.
2 Loads, 3 of 5 Shots
The POI had changed drastically due to differing harmonics.
The last 2 shots are using my winter load of IMR 4831.
Just a few degrees lower than 40ºF and the summer load starts to show signs of a POI change, but fairly predictable.
2 Hits, 2 Inches, 400 Yards
[Oops! Was the wrong video!]
Above 40ºF and the summer load's POI is right where it should be.
One Inch Passed Sundown
If I shoot that summer load from 40ºF to 95ºF, the POI will remain constant. I shoot my winter loads from -10ºF to 50ºF before I see a definite change in POI. It seems like the magic number is close to 40ºF.
Even using Varget a Hodgdon Extreme powder i need to have 2 different loads.
Here is a video of a 350 yard miss, (1 of 3, all close POIs,) using my summer load of Varget in 22ºF.
2 Loads, 3 of 5 Shots
The POI had changed drastically due to differing harmonics.
The last 2 shots are using my winter load of IMR 4831.
Just a few degrees lower than 40ºF and the summer load starts to show signs of a POI change, but fairly predictable.
2 Hits, 2 Inches, 400 Yards
[Oops! Was the wrong video!]
Above 40ºF and the summer load's POI is right where it should be.
One Inch Passed Sundown
If I shoot that summer load from 40ºF to 95ºF, the POI will remain constant. I shoot my winter loads from -10ºF to 50ºF before I see a definite change in POI. It seems like the magic number is close to 40ºF.
- Nov 4, 2004
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Dr Mike covered it well.
All powders are temperature sensative, some more and some less than others.
JD338
All powders are temperature sensative, some more and some less than others.
JD338
RiverRider
Handloader
- Dec 9, 2008
- 1,436
- 71
Wildgene, where did you find that information on Ramshot powders? I spoke to a Western Powders tech or ballistician about Ramshot powders one day, probably about a year ago. What he told me was quite different from what you have posted. I would like to know for sure what the story is. Do you have a link to that info?
The man at Western told me that Ramshot powders exhibit a 1% velocity variation over a range of [something like] -40*F to 140*F in milder rifle cartridges such as .223 Remington and .308 Winchester, and pointed out the fact that the variation would be much more pronounced in a cartridge like 7mm STW or one of the Ultramags.
I wonder why the information he gave is so different from what you have provided. Maybe there is a perfectly logical explanation.
****************
I realize that no powder will be perfectly insensitive to temperature extremes, but some appear to be much better than others. The conditions that I hunt in may never fully tax the temperature tolerance of the powders I use, but I believe in building in whatever advantage I can get and I usually try one or two of the ADI/Hodgdon powders during initial load development. I usually do not, but might possibly find myself hunting in temperatures as low as 10 to 20 degrees F. Temps as high as 105 or more are definitely a possibility. The Ramshot powders, Re15, and Re17 have been my alternative choices to date.
The man at Western told me that Ramshot powders exhibit a 1% velocity variation over a range of [something like] -40*F to 140*F in milder rifle cartridges such as .223 Remington and .308 Winchester, and pointed out the fact that the variation would be much more pronounced in a cartridge like 7mm STW or one of the Ultramags.
I wonder why the information he gave is so different from what you have provided. Maybe there is a perfectly logical explanation.
****************
I realize that no powder will be perfectly insensitive to temperature extremes, but some appear to be much better than others. The conditions that I hunt in may never fully tax the temperature tolerance of the powders I use, but I believe in building in whatever advantage I can get and I usually try one or two of the ADI/Hodgdon powders during initial load development. I usually do not, but might possibly find myself hunting in temperatures as low as 10 to 20 degrees F. Temps as high as 105 or more are definitely a possibility. The Ramshot powders, Re15, and Re17 have been my alternative choices to date.
DrMike
Ballistician
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RiverRider
Handloader
- Dec 9, 2008
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Thanks Dr.Mike. I will definitely check it out.
RiverRider
Handloader
- Dec 9, 2008
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Wow...all I can say is that I am disappointed to have been misled by someone at Ramshot. I suppose it is possible the man said "three percent" but I am pretty sure I heard him say "one percent."
But still...if my .222 Remington loads are going to vary by 3% from -40*F to 125*F, that's only about a 100 fps difference over a 165-degree range of temperatures and I am pretty danged sure the range of temperatures I will hunt in would be about half that. I guess I can live with about a +/-25 fps range of velocities.
I'll also have to call out John Barsness, who wrote the following in Handloader back in 2003, I believe:
Now, I think the FAQ page at Ramshot's website is using the English language very carefully in saying that temperature variations will have some effect on velocity and therefore Ramshot's powders "are not insensitive." I guess I can cut Barsness some slack too...it all seems to be relative.
One of these days I'll sit down and load up a sufficient quantity of ammo using various powders including those said to be insensitive and those reputed to be the MOST sensitive, then I'll shoot some of it in the summer and some of it in the winter (such as it is in my part of the world) and chronograph it. I guess that's the only way to qualify all these things.
But still...if my .222 Remington loads are going to vary by 3% from -40*F to 125*F, that's only about a 100 fps difference over a 165-degree range of temperatures and I am pretty danged sure the range of temperatures I will hunt in would be about half that. I guess I can live with about a +/-25 fps range of velocities.
I'll also have to call out John Barsness, who wrote the following in Handloader back in 2003, I believe:
Now, I think the FAQ page at Ramshot's website is using the English language very carefully in saying that temperature variations will have some effect on velocity and therefore Ramshot's powders "are not insensitive." I guess I can cut Barsness some slack too...it all seems to be relative.
One of these days I'll sit down and load up a sufficient quantity of ammo using various powders including those said to be insensitive and those reputed to be the MOST sensitive, then I'll shoot some of it in the summer and some of it in the winter (such as it is in my part of the world) and chronograph it. I guess that's the only way to qualify all these things.
DrMike
Ballistician
- Nov 8, 2006
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For many powders, a 100 fps difference in velocities measured between mid-summer and mid winter (85F to -40F here) is reasonable to expect with most powders. I have measured significant variations even on Hodgdon Extreme powders and on the VihtaVuori 500 series powders. It is my habit to measure velocities on an ongoing basis during hunting season just to ease my worried mind.
RiverRider
Handloader
- Dec 9, 2008
- 1,436
- 71
Dr.Mike, what are some of the most sensitive powders you've worked with? And some of the least sensitive?
I was sitting here thinking about some of the velocity variations I've seen. There have been times that I see a noticeable difference in velocity between "identical" loads loaded at different times but fired in very similar circumstances. I think that is a good reason to stipulate that any experimentation would require loading all the ammo at the same time to be shot at different times of the year in order to get meaningful velocity data.
I was sitting here thinking about some of the velocity variations I've seen. There have been times that I see a noticeable difference in velocity between "identical" loads loaded at different times but fired in very similar circumstances. I think that is a good reason to stipulate that any experimentation would require loading all the ammo at the same time to be shot at different times of the year in order to get meaningful velocity data.
DrMike
Ballistician
- Nov 8, 2006
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RR,
Off the top of my head, among the most sensitive have been IMR4831 and IMR4350; velocity drops were in the range of 5% when moving from our summer highs to winter lows. I witnessed extreme variations in velocities with IMR7828, A8700 and RL25 when working with a Lazzeroni 7.82 Warbird. These three powders in particular were greatly affected by moving from cold to hotter temperatures. Likewise, moving back the other way witnessed some steep velocity drops. Among the least sensitive powders that I've used are the VihtaVuori powders. I use a fair amount of VN550 and VN560, especially in my 7 WSM and my 300 WSM. I've also tested VN165 extensively in my .280 and in my 7mm RM, and I can say that velocity changes are not pronounced with this powder in these cartridges. I have found Benchmark to relatively stable when shooting in my .356 and .358, but then I'm not wringing high velocities out of these cartridges or shooting at long distances. A 150 yard shot with either of these rifles would be a long shot. Most of my shots are well under 100 yards with these cartridges. I haven't really tested the Ramshot powders at extremes, though there is a slight, though noticeable, velocity drop when moving from summer highs to late fall (say 85F to 30F).
Off the top of my head, among the most sensitive have been IMR4831 and IMR4350; velocity drops were in the range of 5% when moving from our summer highs to winter lows. I witnessed extreme variations in velocities with IMR7828, A8700 and RL25 when working with a Lazzeroni 7.82 Warbird. These three powders in particular were greatly affected by moving from cold to hotter temperatures. Likewise, moving back the other way witnessed some steep velocity drops. Among the least sensitive powders that I've used are the VihtaVuori powders. I use a fair amount of VN550 and VN560, especially in my 7 WSM and my 300 WSM. I've also tested VN165 extensively in my .280 and in my 7mm RM, and I can say that velocity changes are not pronounced with this powder in these cartridges. I have found Benchmark to relatively stable when shooting in my .356 and .358, but then I'm not wringing high velocities out of these cartridges or shooting at long distances. A 150 yard shot with either of these rifles would be a long shot. Most of my shots are well under 100 yards with these cartridges. I haven't really tested the Ramshot powders at extremes, though there is a slight, though noticeable, velocity drop when moving from summer highs to late fall (say 85F to 30F).
Ridge_Runner
Handloader
- Sep 29, 2006
- 1,377
- 700
if you read the label, and it says it contains nitroglycerine, reguardless of how it looks its ball (double based) powder, the nitroglycerine makes it more temp sensative than a powder that only contains nitrocellulose. all powders are somewhat temp sensative, but the ball powders are worse. the slower burning they are the worse the effect is, this is my experience. I have saw as much as 200 fps increase in MV just from shooting 80 degrees instead of 50, thats using a very very slow burning ball powder called WC872.
But you can work with temp sensativity, its the lot to lot variences of some powders that cause me to drop them like a hot potatoe.
RR
But you can work with temp sensativity, its the lot to lot variences of some powders that cause me to drop them like a hot potatoe.
RR
DrMike
Ballistician
- Nov 8, 2006
- 37,312
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You are correct that the higher the nitroglycerine content, the more effected by temperatures, unless there are significant stabilisers and deterrents introduced; nitrocellulose is certainly more stable than nitroglycerine. You are also correct that the sensitivity to temperature appears to be pronounced as burn rate goes down. As I said, I usually check my loads near the time of hunting. I'm fortunate in that I'm able to do this as I'll be at the range at some point most weeks. I opt not to shoot in the enclosed shack if at all possible during mid-winter to avoid introducing another variable to the collection of data.
RiverRider
Handloader
- Dec 9, 2008
- 1,436
- 71
wildgene":3j3ynwrq said:
I am reading this very carefully, and what I am getting out of this is that nitroglycerin content can be a part of programming a powder to be insensitive to temperature variations. I also would point out that they are saying "complete temperature stability." I'd point out that Ramshot powders are all spherical---none are extruded.
Two powders that are marketed as being temperature tolerant are Re15 and Re17. These are both double-based and contain some nitroglycerin, so they probably serve as a pretty good example of a double-based propellant with temperature stability. It's too bad they haven't treated Re22 the same way---I'd be using it in .280 Remington.
I looked at an MSDS for H4831SC over at the Hodgdon website, and their powders seem to be mainly nitrocellulose, but also contain 2,4-dinitrotoluene which is similar to and a precursor of TNT. Anyway, there's no nitroglycerin in the Hodgdon powders so technically they are single-based (but DNT...really now!).
While I was at the Hodgdon site I looked around some (I am a bit embarrassed that I was not aware of Ramshots statements in their FAQ section), and I found some interesting stuff in regards to temperature tolerance. There are several pages to look at, including one that shows velocity and pressure effects of temperature comparing several different propellants. It's worth looking at:
http://www.hodgdon.com/smokeless/extreme/index.php
I'd like to see a lot more objective data on this subject. And I hate to make it even more complicated than it already is, but I have to wonder if primer changes could influence the way a powder performs at temperature extremes. The conventional wisdom is that heavy charges of slow-burning powders sometimes require a magnum or hotter primer in cold weather so it would seem that the answer is "yes."
I find this all to be one of the most interesting subjects in all of handloading!
