Powder Stability.

[DartonJager]

Tag and at what rate is a powder considered having an unacceptably high temperature sensitivity?
My 300 WSM shoots ABSOLUTE bug holes with IMR 4831.

 

[DartonJager]

So am I understanding this correctly that the data shows a specific increase in velocity in proportion to a specific rise in temperature?

If so I'm a little lost because I'm not quite understanding the significance because I did not see a temperature minimum or maximum at when the ambient temperature will begin to affect the powders performance in terms of velocity.

Should I see the listed velocity increase when the temp goes from 32* to 42* or only after say for the sake of argument when the ambient temp is at 75* and rises to 85*?
Or in other words what is the minimum ambient temp at which it will begin to cause the listed rises in temperature?

To the best of my knowledge in 30+ years if memory serves me I have never rifle hunted in temps above 40* so the reason for my questions because if there are no measurable affects of temperature till well above 40* then I should have little to worry about.

 

[Pdvdh]

The rate values are generalized values and non-specific to outdoor ambient temperatures.
A guy would like to think they apply across the most common range of outdoor ambient temperatures, and that might be so, with some or most of the powders.
But I tested powders that yielded different rates at different ambient temperatures. This was most pronounced when temps dropped below 35-40F, and worse as temps dropped even colder.
From what I've read, a guy might expect the same in really high outdoor ambient temps, compared to room temperature (72F).
I presume the rates are most representative within "common" outdoor temperature ranges, say 45-75F. My own rule of thumb is the more extreme my outdoor temps, the more I need to test for my own uses.

 

[backwoods83]

Well, for the ones still looking at this. RL33, since mentioned so often, is made from the same base powder as VV N570, both are bred from RS80, they have different retardant compounds, which leaves RL33 as slightly slower, and N570 as slightly higher energy, their sensitivity is close though, and isn't bad at all, about a half a fps per degree, with the majority of that being below 35 degrees, and above 85 degrees. In the middle, there's not enough difference to even talk about. RL16 and 23 fall just short of the stability of Varget, slightly edging out H4350. RL26 with high densities doesn't change enough between 20 and 90 degrees, to even worry about, but on the very high or low ends can get a little squirrely, or with low densities and a bad primer choice. I've found that CCI450s and Fed210ms yield the best results unless you're trying to ignite over 80grns, then I switch to CCI 250s, everytime I've tried 215Ms, I've had pressure spikes and terrible SDs. Also N565, depending on the lot, is all but identical to RL26, and Imr4955 isn't terribly far off, with the stability edge going to the Imr due to its coating. 7977 to me, seems a low energy version of 7828, slightly slower burn wise and a tad less temperamental, but I still prefer 7828. Imr8133 is probably the most stable powder made to date, and reacts differently in different cartridges, sometimes close to H1000, sometimes close to RL33. It also yields about 40fps more velocity if it's dried, as do a lot of other powders, but it doesn't effect the burn characteristics of 8133. Feel free to keep adding, more information is always a help to someone.

 

[trailrider121]

Outstanding, and thank you for the information on powder.

 

[backwoods83]

You're welcome. I'll try to continue to add as I go. I have almost as much fun trying new combinations, as I do hunting or shooting long range steel matches.

 

[jpretle]

It also yields about 40fps more velocity if it's dried, as do a lot of other powders

Not so sure what you mean by this. Please explain. Procedure????

 

[Pdvdh]

Well, for the ones still looking at this. RL33, since mentioned so often, is made from the same base powder as VV N570, both are bred from RS80, they have different retardant compounds, which leaves RL33 as slightly slower, and N570 as slightly higher energy, their sensitivity is close though, and isn't bad at all, about a half a fps per degree, with the majority of that being below 35 degrees, and above 85 degrees. In the middle, there's not enough difference to even talk about. RL16 and 23 fall just short of the stability of Varget, slightly edging out H4350. RL26 with high densities doesn't change enough between 20 and 90 degrees, to even worry about, but on the very high or low ends can get a little squirrely, or with low densities and a bad primer choice. I've found that CCI450s and Fed210ms yield the best results unless you're trying to ignite over 80grns, then I switch to CCI 250s, everytime I've tried 215Ms, I've had pressure spikes and terrible SDs. Also N565, depending on the lot, is all but identical to RL26, and Imr4955 isn't terribly far off, with the stability edge going to the Imr due to its coating. 7977 to me, seems a low energy version of 7828, slightly slower burn wise and a tad less temperamental, but I still prefer 7828. Imr8133 is probably the most stable powder made to date, and reacts differently in different cartridges, sometimes close to H1000, sometimes close to RL33. It also yields about 40fps more velocity if it's dried, as do a lot of other powders, but it doesn't effect the burn characteristics of 8133. Feel free to keep adding, more information is always a help to someone.

Many of your experiences match mine. CCI 250 primers, for example. Just had the identical experience compared to the 215Ms.

 

[backwoods83]

Yeah, primers play a much bigger role than most people think. They don't realize that all large rifle, small rifle, or their magnum variants aren't created equal. Of course, primers of different brands have a totally different flame path as well, like Federals pretty much shoot a straight flame, where as, Winchester primers shoot a fireball, but they were originally designed to ignite ball powder.
By drying powder, that means leaving it out for a couple days in a glass baking dish or actually putting it in the oven on a very low temperature. If you've never paid attention, powder is kinda sticky from the additives, or "wet", Retumbo clumping in a sealed container is a prime example, as Retumbo is famous for that, H1000 is known to do it as well. I do however recommend doing this before your load work up and starting low, if you decide to try drying powder, even though, when done correctly, it should have no effect on the burn rate of the powder. Typically it just gains a little velocity and sometimes more stability, and is ever so slightly easier to ignite.

 

[trailrider121]

Yes Primers do play a big role. I usually test primers after a good powder node and re working around it retesting powder. Then I move onto seating depth and neck tension testing.

Interesting read about powder drying.

 

[338 dude]

I have been collecting data on my own, from accurate shooter, 24hr campfire, snipers hide, AR15.com, sniper central, etc.. most of it is my test. The moderators are welcome to make it a sticky and anyone can feel free to add. Since the topic comes up on a regular basis I figured I would post up a powder sensativity thread on all the data I've collected, it will be from fastest to slowest in fps per degree of temperature change.

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 *
RL33, still trying to get my data for this one.
US869 1.68 fps per *
H50bmg 1.64 fps per *

Feel free to add at any time, and remember that load density and primer type also effect these numbers, these are only to give you a ballpark figure. Info like this helps me when I'm using my ballistics calculator so I decided I would spend a few minutes to share it. Happy shooting.

I have saved them in my phone I saw a post you made here or elsewhere a couple months ago

 

[backwoods83]

Some powder and primer "best" matches from my experience.
H4895 Fed210ms or CCI450s, but BR2s work decent.
Varget is pretty much the same as H4895 in this case.
H414/W760 Winchester LRP or CCI 250s
H4350 Fed210ms with Br2s giving similar results.
RL17 Federal 210Ms.
RL16 210Ms
RL19 CCI 250s
Imr4350 210Ms or Br2s
Imr4064 Br2s, 250s, or #34s
Imr4166 210Ms
Imr4831 CCI 250s
Imr4895 210Ms
Imr7828 CCI 250s or 34s
Imr7977 215Ms
Imr8133 215Ms
H1000 215s or CCI 250s
Retumbo 215Ms
Magnum 215Ms
Magpro, MRP, RL22, and N560 CCI 250s
RL26 210Ms or CCI 250s
RL25 210Ms or CCI 250s
RL33 or N570 215Ms
With any powder using small primers, I prefer CCI450s or Remington 7.5 brs to insure ignition. 205MARs are decent as well, and will take the pressure. I never reccomend Winchester srps, CCI 400s, or regular 205s, unless using a light load of a fast powder that is easy to ignite, like RL7 in a mild 222Rem load.

 

[backwoods83]

Someone posted the data on the hide and Facebook, so it's hard to say. Some one was arguing about it on Facebook, and had no idea they were talking to the person that wrote it.