Powder Burn Rates and Temp Sensitivity

[NugginFutz]

I've seen plenty of burn rate charts, and a couple of attempts at quantifying temperature sensitivity. I have never seen both in the same chart, so I thought that this might be something a few of us would consider useful.

The sources for burn rates include Hodgdon, Alliant, Western Powders.

The temperature data has been gleaned from several sources, including Hodgdon, ARFcom and AccurateShooter.com, LongrangeHunting.com and, of course, 65grendel.com. I am more than willing to incorporate any additional temperature sensitivity data the horde has accumulated.

Just to be clear, it must be understood by all that this is strictly for reference, and should not be considered as a powder substitution chart. As always, please refer to reputable reloading manual or source for load data.


Fastest powders at the top, slowest at the bottom. Sensitivity data, where available, is expressed as fps/Deg F.

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[JASmith]

Thanks!

With respect to BFT's "one powder" thread, the numbers wuld seem to tip the scales in favor of 8208.

Not many of us have reported loads with Varget??

[NugginFutz]

Thanks!

With respect to BFT's "one powder" thread, the numbers wuld seem to skip the scales in favor of 8208.

You're welcome!

Looking at IMR 8208 XBR @ 0.59 and AA2520 @ 0.98, its apparent that the 8208 is more stable, but temperature stability is only one part of the overall equation. It's also clear that 8208 is a faster powder, and will reduce how much can be used before exceeding pressure limits, which then limits your peak velocity.

Not many of us have reported loads with Varget??

Varget is not a popular powder for the Grendel, simply because is is too slow and not dense enough to get a useable load into the Grendel case. It is, however, a very popular powder in the larger caliber rifles, and its stability has been reported quite often among target and the long range crowds.

This brings me to a bit of a conundrum. The data I'm collecting is from a variety of sources, and across multiple cartridge types. For these numbers to have true statistical significance, they should be derived from results reported from the target audience as much as possible - Grendel shooters. Don't get me wrong - the data is still meaningful. In relative terms, the data already collected shows which powders are more temperature sensitive than others. It would take a large sample from the Grendel crowd, however, before anyone could look at this table and say "Ah, hah! My pet load of XYZ powder will see a MV change of ~100 fps for my XLD bullet, today."

Do I really believe this chart will ever get to that point? Not in 20 years. Many so-called pet loads have already been identified, and the frontier days of discovering loads for the Grendel are behind us, for the most part. (Thank the Lord, since it means fewer busted fiddly bits.) But I will continue to update it, if and when additional data comes in.

[1911man]

Yeah, this makes me even more confident about using XBR 8208 for my Pet Load. I have quite a few loads with various bullets and powders that will shoot sub minute out of my barrel, but XBR and AR Comp are the two powders I trust the most to be temp stable. CFE has proven to be terrible for me in this regard among other problems I have with that powder. Varget is absolutely my favorite powder for larger calibers. It has proven to make extremely accurate loads and to be consistent in a variety of temperatures and conditions. I get vary little zero shift on my Varget load on my .308 when going from shooting in 90 degree temps to 30 degrees. In fact the shift is so small it very well could just be me as the change in impact. The position I am in, maybe how I have the shot lined up. Every year in each change in season I take each of my rifles out and shoot groups to compare. I have an entire folder full of them. I have not done extensive testing with my Grendel yet as I have not owned it a full year but so far the 8208 is looking good.

[NugginFutz]

Agreed - I like 8208, even if it can't generate some of the MV's other powders can. I like it for its stability and availability. A lot of folks (myself included) have been warning those considering using 8208 about it being a fast powder, but I have a very good load worked up for the 123 Amax with acceptable MV's and excellent accuracy.

Do your semi-annual outings include the use of a chronograph, by any chance? If so, I would be happy to crunch numbers and incorporate the findings in the chart.

As far as your sentiments about Varget are concerned: It is my absolute favorite powder in my larger case capacity rounds (.243, .308, 22-250, etc.) My .308 shoots bug holes with amazing consistency, year round (0 - 110 'F). Among my reloading friends, we often remind each other that "If you can't get it to shoot in your rifle with Varget, your rifle will never shoot it". While not universally true, that seems to be the case in over 90% of the time. It's just a real shame that the volume of Varget needed for competitive velocities exceeds the Grendel's case capacity.

[kmon]

I have been using Varget since it was a new powder and still use a lot of it in larger cases. While I disagree that it is too slow for the Grendel since it is faster burning than CFE223 which works well in the Grendel, it is bulky and does not meter as well as the ball powders.

One I started working with is IMR 4166 which is between 8208 and Varget on the burn rate chart, temperature stable (as far as that really goes) and has the copper fouling reduction like CFE. Only issue is compressed loads due to lower density and being an extruded powder it does not meter as well. Chargemaster has no issues dropping it though. Was given a few lbs of it to try so thought why not try it in the Grendel. Will get back to working more with it after hunting season, but does show promise for accuracy with 123gr SST and A-Max bullets at slightly higher velocity than the factory Hornady loads, without high pressure indicators.

[LRRPF52]

Have you tried vibration-settling Varget to get more case fill?

[NugginFutz]

One I started working with is IMR 4166 which is between 8208 and Varget on the burn rate chart, temperature stable (as far as that really goes) and has the copper fouling reduction like CFE. Only issue is compressed loads due to lower density and being an extruded powder it does not meter as well. Chargemaster has no issues dropping it though. Was given a few lbs of it to try so thought why not try it in the Grendel. Will get back to working more with it after hunting season, but does show promise for accuracy with 123gr SST and A-Max bullets at slightly higher velocity than the factory Hornady loads, without high pressure indicators.

I'm curious how you're getting MV's higher than Factory 123 SST. I'd previously tried 4166 with 123 Amax, and could not jam enough powder into the case to come anywhere close to Factory MV's let alone those I was getting with 8208. With a highly compressed load of 27.6gr, my 22" barrel could only produce 2400 fps with 4166. Factory 123 SST runs at 2640 fps.

[kmon]

Have you tried vibration-settling Varget to get more case fill?

Only way to get enough in the case for it and 4166 falls into that realm as well. Have used the tumbler and have used the electric tooth brush.

4166 29.5 gr, 2.265 inches with 123gr SST gives me 50fps more than the Hornady factory rounds I ran through the Chrono the same shooting session. Would treat that load like you would 28.5 with IMR 8208 and approach only with caution if at all. In the bolt action I did go to 30 but just a hint of sticky bolt lift and velocity for one round spiked to 2730fps. only shot 2 at that load. The 29.5 worked well in my bolt action, in the AR cases and primers looked good but brass location after firing looks like was a little over gassed.

Planning to do more with it most likely in Feb for load workup then test in June or July in Texas heat. That data above was on a 100+ degree day in July

[Hoser1]

It appears that Reloader 12 would make a good choice, does anyone have any loading data on that powder or have tried it. I use 10X with 95 gr vmax and have good groups with it. I don not have any chrono data to know what speed the round is traveling. What about LT 30, That is a very very short cut spherical powder, has anyone tried it? I found it on the shelf, not sure though haven't heard any body talk about it on here. I looked it up on westerns web page, FPS seem slow compared to other powders.

[kmon]

Do they still make Reloader 12, it is not on their website anymore.

[NugginFutz]

Do they still make Reloader 12, it is not on their website anymore.

No, they sure don't. Discontinued around 2011, it's still listed on Hodgdon's burn rate chart, which is one of the sources I used to assemble this table. I'm considering taking it off the list since the number of times I hear about the stuff turning up is quite low. A can of Hercules Reloder 12 turned up in the wild, just this summer.

[1911man]

Agreed - I like 8208, even if it can't generate some of the MV's other powders can. I like it for its stability and availability. A lot of folks (myself included) have been warning those considering using 8208 about it being a fast powder, but I have a very good load worked up for the 123 Amax with acceptable MV's and excellent accuracy.

Do your semi-annual outings include the use of a chronograph, by any chance? If so, I would be happy to crunch numbers and incorporate the findings in the chart.

As far as your sentiments about Varget are concerned: It is my absolute favorite powder in my larger case capacity rounds (.243, .308, 22-250, etc.) My .308 shoots bug holes with amazing consistency, year round (0 - 110 'F). Among my reloading friends, we often remind each other that "If you can't get it to shoot in your rifle with Varget, your rifle will never shoot it". While not universally true, that seems to be the case in over 90% of the time. It's just a real shame that the volume of Varget needed for competitive velocities exceeds the Grendel's case capacity.

Yes, I do bring a chronograph. I have plenty of data on my XBR loads in warm weather. But none yet in cold weather. It was 70 degrees outside today, in fteaking December.

[JASmith]

This chart is more useful than one might think at first!

[NugginFutz]

Since phot(slop)bucket started messing with people's links, I dropped them like the steaming turd they became. I'm replacing the links I posted here, as I find them, including the picture in the OP. It still seems quite relevant.