Appreciate the data. My 300WSM is 22" + break. 1 in 12. Getting great results with 65 grains H4350, 165 Nosler BT, Norma brass.Powder Temp Stability Test – 8028XBR, Varget, H4350, RL19, RL26, N560
Really cold weather, plus boredom inspired me to conduct a fairly extensive powder stability test this weekend on several of my hunting rifles.
Rifle Specs…
300 WSM – 1:10 twist 20" Proof Carbon barrel
7 SAUM – 1:9 twist 26" Proof Carbon barrel
308 Win – 1:11.25 twist 20" Bartlein barrel
6.5 Creedmoor – 1:8 twist 22" Bartlein barrel
6.5x47 Lapua – 1:8 twist 26" Bartlein barrel (target rifle)
223 Rem – 1:8 twist 24" Bartlein barrel (target rifle)
Testing Procedure…
4-6 shots (usually 5) were shot with cold ammo/rifle, then 4-6 shots were shot with Warm ammo/rifle. Speeds were recorded with a Labradar, and I did not delete ANY of the shots, so any outliers were left in the data. Cold ammo was left out overnight with Temps around -5 to +5 degrees F. Actual temp was recorded at the time of shooting the Cold Group. For Cold group shooting the rifle was left outside for at least an hour for the bore to get cold. Warm Groups were shot with ammo that was left in my house at 70 degrees F, and the Rifle was stored in my work shop for at least 1 hour prior to shooting, which is kept at 55 degrees F. Then the ammo was quickly loaded and shot outside within 5 min.
I will summarize the data below by including the following…
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Powder Type
Caliber
Load Data
Warm Group Temp
Warm Group Avg
Warm Group SD
Cold Group Temp
Cold Group Avg
Cold Group SD
Temp Difference
Avg Vel Difference
*********Here's the Data***********
THE USUAL DISCLAMERS APPLY WITH THE LOAD DATA.
!!WORK UP YOUR OWN LOADS FOR YOUR RIFLES!!
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Powder Type – H4350
Caliber – 6.5x47 Lapua
Load Data – 40.0gns, Lapua Case, CCI450, 140 Hybrid
Warm Group Temp = 70F
Warm Group Avg - 2781 fps
Warm Group SD – 1.8 fps
Cold Group Temp = 10F
Cold Group Avg - 2767
Cold Group SD – 10.5
Temp Difference – 60 Degrees
Avg Vel Difference – 15 fps
NOTE: Good SD's and Temp stability with H4350 and the 6.5x47. Most info I've read says about 0.3 FPS per degree of temp change, and that's about what I saw. No surprise here.
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Powder Type – H4350
Caliber – 6.5 Creedmoor
Load Data – 42.2gns, Lapua SRP Case, CCI450, 143 ELDX
Warm Group Temp = 70F
Warm Group Avg - 2676 fps
Warm Group SD – 23.1 fps
Cold Group Temp = 10F
Cold Group Avg - 2649
Cold Group SD – 11.5
Temp Difference – 60 Degrees
Avg Vel Difference – 27 fps
NOTES: The high SD on the Warm Group was mainly due to the very first shot, which was about 50 fps slower than the rest (not sure why). Also note that if you've ever heard of Small Rifle Primers being unreliable with large cases in cold weather, well… I had two rounds misfire on the Cold Group. One of them I tried again and it fired. The other never fired after 3 tries. The 27 fps difference over a 60 degree change is about 0.5 fps per degree. This seems a little high for H4350, but not out of the ordinary.
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Powder Type – H4350
Caliber – 300WSM
Load Data – 63.0gns, Norma Case, CCI250, 178 ELDX
Warm Group Temp = 70F
Warm Group Avg - 2916 fps
Warm Group SD – 18.6 fps
Cold Group Temp = 2F
Cold Group Avg - 2912
Cold Group SD – 9.2
Temp Difference – 68 Degrees
Avg Vel Difference – 4 fps
NOTE: I haven't finished load development with this rifle, but liked what I saw from the results above, so I reran the same test with a slightly lower charge weight. Results below.
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Powder Type – H4350
Caliber – 300WSM
Load Data – 62.5gns, Norma Case, CCI250, 178 ELDX
Warm Group Temp = 55F
Warm Group Avg - 2926 fps
Warm Group SD – 10.0 fps
Cold Group Temp = -5F
Cold Group Avg - 2912
Cold Group SD – 13.6
Temp Difference – 60 Degrees
Avg Vel Difference – 14 fps
NOTE: Still outstanding temp stability in the 300 WSM. I will be working in this range more to develop my hunting load for this rifle.
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Powder Type – RL26
Caliber – 7SAUM
Load Data – 59.2gns, Norma Case, CCI250, 180 VLD
Warm Group Temp = 70F
Warm Group Avg - 2870 fps
Warm Group SD – 5.6 fps
Cold Group Temp = 2F
Cold Group Avg – 2846 fps
Cold Group SD – 8.3
Temp Difference – 68 Degrees
Avg Vel Difference – 24 fps
NOTE: This rifle and load are very well proven for me (low SD's always consistent), so I have a lot of confidence in these numbers. RL26 looks to be about 0.35 fps per degree of temp change. Not bad at all for a powder that is not technically "Temperature Stable".
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Powder Type – 8028XBR
Caliber – 223 Rem
Load Data – 22.5gns, Hornady Case, CCI200, 69 TMK
Warm Group Temp = 70F
Warm Group Avg - 2729 fps
Warm Group SD – 23.8 fps
Cold Group Temp = 10F
Cold Group Avg – 2683 fps
Cold Group SD – 12.1 fps
Temp Difference – 60 Degrees
Avg Vel Difference – 46 fps
NOTE: This rifle and load are just for practicing out to 300 yds, so I don't take a lot of care in loading the ammo, which gives me higher SD's. However, it's apparent that the 8028XBR is effected by low temps quite a bit.
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Powder Type – RL19
Caliber – 300 WSM
Load Data – 66.0gns, Norma Case, CCI250, 200 ELDX
Warm Group Temp = 70F
Warm Group Avg - 2862 fps
Warm Group SD – 30.1 fps
Cold Group Temp = 10F
Cold Group Avg – 2823 fps
Cold Group SD – 24.9 fps
Temp Difference – 60 Degrees
Avg Vel Difference – 39 fps
NOTE: This load just doesn't shoot very well in my rifle, but I had a few rounds laying around from an early attempt at load development, so decide to shoot them. With such high SD's I wouldn't trust this data much, but it shows RL19 to be fairly temp sensitive, which is consistent with what most people say about it.
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Powder Type – N560
Caliber – 300 WSM
Load Data – Norma Case, CCI250, 178 ELDX
Warm Group Temp = 70F
Warm Group Avg - 2932 fps
Warm Group SD – 13.9 fps
Cold Group Temp = 4F
Cold Group Avg – 2847 fps
Cold Group SD – 14.9 fps
Temp Difference – 66 Degrees
Avg Vel Difference – 85 fps!!
NOTE: This was the big loser of this test. I lost 85 fps over a 66 degree temp change! I'm not loading any more of this N560.
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And now for the weirdest of the results…. VARGET, which actually sped up as it got colder…
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Powder Type – Varget
Caliber – 308 Win
Load Data – 45.0gns, Fed Case, CCI200, 165 Partition
Warm Group Temp = 70F
Warm Group Avg - 2699 fps
Warm Group SD – 12.9 fps
Cold Group Temp = 10F
Cold Group Avg – 2724 fps
Cold Group SD – 11.5 fps
Temp Difference – 60 Degrees
Avg Vel Difference – This load was 25 FPS FASTER with a 60 degree Drop in temp.
NOTE: I figured this test could not be right, so I ran it again the next day. Here's that data…
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Powder Type – Varget
Caliber – 308 Win
Load Data – 45.0gns, Fed Case, CCI200, 165 Partition
Warm Group Temp = 70F
Warm Group Avg - 2696 fps
Warm Group SD – 8.7 fps
Cold Group Temp = 2F
Cold Group Avg – 2716 fps
Cold Group SD – 13.5 fps
Temp Difference – 68 Degrees
Avg Vel Difference – This load was 20 FPS FASTER with a 68 degree Drop in temp???
NOTE: I don't understand the Varget results. Weird thing is I haven't shot this rifle/ammo for about a year. I had a bunch of round loaded for it that I remember developing in the summer time (so probably 80-90 degrees), and the boxes were labeled as having a velocity of 2660 fps. So I was surprised to see velocities around 2700 fps when I shot the warm group. Then even more surprised with I saw them speed up with single digits temps.
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Summary
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I mostly found that H4350 is fairly temp stable in the 0.2-0.4 fps per degree range. I also was pleased to find that RL26 was fairly temp stable. N560 was awful, as was 8028XBR (but I only use this for 223 practice ammo).
With regard to Varget getting faster as it gets colder, I am stumped by this. Maybe it has something to do with my specific barrel, or bullet combo. Not sure.
Hope the data is helpful to people.
Powder Temp Stability Test – 8028XBR, Varget, H4350, RL19, RL26, N560
- Thread starter jamiebolseth
- Start date
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Appreciate the data. My 300WSM is 22" + break. 1 in 12. Getting great results with 65 grains H4350, 165 Nosler BT, Norma brass.
brentc
Well-Known Member
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- Apr 3, 2009
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The best way to optimize temp stability is to take the time to make sure your load is nailed. The right case prep, the right powder charge, the right seating depth, and the right primer all make a significant difference no matter what label is on the bottle. Bad temp stability is a good indicator of a bad load combination, not necessarily an indicator of a bad powder.
You think that applies across the gamut of powders?
Based on my temp sensitivity testing, I think it would require a full career of effort to document this, one way or the other.
Op was using LabRadar also. So we have a conundrum.
Could you share your RL26 data?
Rudolph Ferdinand
Well-Known Member
Doing any testing, it takes a long time and the cost of conducting such a test of various powders. Thank very much for doing the hard work of us all. But, I believe that such tests are needed people need to remember that work in one location may not do the same thing somewhere else. I had a problem with finding factory ammunition from Hornady in 6.5 CM in my AR-10 with two different barrels installed, somewhere in the state of Alaska there are these guys using Hornady factory (match) that is working for them but that same ammunition will not operate my AR-10 in the southern portion of the state. What may work in one's area? Do your testing for where you live.
I would say you need to get your gun looked at. The chances of a regional difference in ammo performance from South to North Alaska affecting whether the AR cycles or not is pretty remote on the scale of likely causes. Far more likely that it has something to do with your gun and its gas pressure system, especially shooting full pressure factory ammo.
Great information and thanks for compiling it!
The issues I have heard on RL26 have all been above 85 degrees. I would still like to hear more from those that have experienced that. I'm not surprised at all on the N560, it's a double based powder and they all tend to show more instability from what I've heard.
This chart that I've attached has been floating around for awhile and some might find correlation between their own experiences and what is listed. Some of them track precisely with what I have seen in my own testing.
The issues I have heard on RL26 have all been above 85 degrees. I would still like to hear more from those that have experienced that. I'm not surprised at all on the N560, it's a double based powder and they all tend to show more instability from what I've heard.
This chart that I've attached has been floating around for awhile and some might find correlation between their own experiences and what is listed. Some of them track precisely with what I have seen in my own testing.
Attachments
Satterlee Scott
Well-Known Member
tangodown
Well-Known Member
mmmmmmmmmmmmmmmmmm
Savage 22-243 AI
Well-Known Member
Great test, thank you!
We have always found higher velocities in winter at lower temps compared to summer temps. Air Density is my guess.
Rel.17 and Rel.19 always caused problems in high temps if loaded in winter or spring with avg. temps. Varget is my favorite of all for the most versatile powder for Prairie Dog rifles to big game rifles. Doesn't cover all of the calibers but enough.............thanks again.......
We have always found higher velocities in winter at lower temps compared to summer temps. Air Density is my guess.
Rel.17 and Rel.19 always caused problems in high temps if loaded in winter or spring with avg. temps. Varget is my favorite of all for the most versatile powder for Prairie Dog rifles to big game rifles. Doesn't cover all of the calibers but enough.............thanks again.......
