Powder Temp Stability Test – 8028XBR, Varget, H4350, RL19, RL26, N560

[odoylerules]

I always like seeing info like this. I wish AB would start testing powder along with bullets.

That would be awesome if they did!

 

[jamiebolseth]

For the guys interested in RL26 data I did a test with the same 7 SAUM last Spring testing my cold bore plus 2 shots at 950 yds each day for 6 days. I wasnt really testing temp stability as much as cold bore shift. It was 19 shots total (shot 4 shots one day because I misjudged the wind and missed the target on the cold bore). I recorded velocity and placement on the target for every shot. Temps ranged from 36 degrees to 75 degrees.

Long story short...
There was a noticable (though small - around 10 fps) drop in velocity from the cold bore shot. But at the end of all 19 of those shots the SD was 11 fps spanning 6 days and about 40 degrees in temp. So that convinced me that RL26 was fairly stable in mid temps (30 to 75).

This weekend's test suggests it's a little more sensitive below freezing temps, but still pretty good. At least in my 7 Saum.

 

[coop2564]

Would be interesting to see the RL26 load in temps over 90°. I found very little temp swing from 4° to 80°. But once I hit 85°, pressures really spiked quickly. 90° was slightly overpressure, and 110° was extreme. Gaining 50fps from 84° to 110° and becoming soconcerning, I worked up a load with H1000 for higher temperature units where they swing from 50-90°+ between sunrise and midday.

Ive shot it up to 105 degrees in TX many times! I have no idea where this rumor started i have not seen any difference going over 85 degrees!

 

[Predator 22]

Ive shot it up to 105 degrees in TX many times! I have no idea where this rumor started i have not seen any difference going over 85 degrees!

What temps did you work up your load in? Do you have any velocity data?

 

[newtonian]

This is a beautiful piece of rifle science. Thanks!

 

[parshal]

I valued the RL26 data, as that's a powder I use in 2 hunting rifles. BTW, my temp sensitivity data is similar, with RL26.

I wish I had the same results with R26. I seem to be the only one who's done similar tests and didn't find R26 as stable as others.

 

[cpipacer]

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…

*******************************
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!!
*****************************************************

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.



*****************************************************

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.


*****************************************************

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.

*****************************************************

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.


*****************************************************

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".


*****************************************************

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.


*****************************************************

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.



*****************************************************

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.


*****************************************************

And now for the weirdest of the results…. VARGET, which actually sped up as it got colder…

*****************************************************

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…


*****************************************************

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.


****************
Summary
****************

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.

 

[cpipacer]

Nice work.

This is why these forums are outstanding everyone contributed useful information.
Thanks

 

[coop2564]

Orginal load was @65 degrees went up to 47.8gr 2890 avg. had best group at 47.2gr 2857 avg. settled at that load @ 90 degrees it shoots 2874 @ 105 degrees 2888 avg. Never had any pressure signs. Many are loading the CM up to 49gr even 50grs @ cooler weather I could see problems potentially if you load that hot in cool weather and go shoot in hot when u r max out @ 40 degrees! With my conservative load Im still 200 fps faster than factory loads with RL26!
Some how this powder just doesn't show pressure signs like other powders. However physics still says it has to be there. So that's why I load it down some.

 

[JohnnieB]

Great work and a great piece. Very informative and well written.

Might have to rethink my goto load in my 340....its N560.

 

[woodnut]

Here's my 2 cents. I don't have much data; but I did do one on RL19 in my 6 CM. I know I'm not going to be shooting it in temps of 40*,so I found two days of 90 and 75 degrees. I have a starting load with the 108 ELDs that at 75 degrees had an SD of only 5.09 and ES of 10.84 and vel. avg. of 3061. At 90 degrees, the 105s (I didn't shoot, for some unknown reason, the 108s at 90) gave an ES of 27.65 and SD of 14.10 and vel. of 3166, a 105 fps diff. Yes, a big vel. diff.; but accuracy was well under 1/2 MOA for all. I figured to stop testing as that would be plenty good for prairie dogs and steel to 1000! I was having a very hard time finding H4350 and heard it was a hot burning powder anyways. I tried several other powders and RL 19 just seemed to be the slightly better choice for this 6 CM and my use. I also figured if it got hotter than 90, which it could in S.D., my starting load would still be safe. Hope I'm right!

 

[bigbulls]

Great info, thanks

 

[Johnslam]

Thanks for the extensive write up.

 

[reubenski]

Great work! That's a lot of good info.

I have temp tested RL26 as well and found it to be very stable. I put 5 rds in my beer fridge for 3 hours, 5 rds in my gunbox in my garage, and 5 rds in the Colorado sun on top of a black Foldgers lid with a glass measuring bowl on top of them. I measured the temps with a Milaukee IR gun and with my Kestrel at 36*, 55*, and 83* respectively. I shot them with my rifle at ambient 55* temp. All pretty quickly. 5 hot, then 5 cold, and then the 5 ambient. There was almost no difference. I didn't think about conditioning the rifle as well like you did. I guess I was trying to isolate everything. The load was a proven stable and hammer of a load that I used starting in February in New Mexico and thru the summer in Colorado. It reflected those testing results in practice. One of the matches I shoot with it, starts at 30* in morning and ends up in the 70's by early afternoon. I am very pleased with RL26. My only gripes would be that the kernals are different sized so trickling down to the kernal is a challenge not worth attempting and I've never gotten repeatable mid single digit SDs with it. But the vertical at distance is good, so I don't sweat it.