Temperature Sensitivity of Alliant Reloder 26

[parshal]

Here's some testing I did with temperatures. Third column is the temp and fourth column is the SD. Loads of the same charge were all loaded at the same time and shot at the different temperature. Both loads and rifle were allowed to sit in those temps for 30 minutes before firing over a magnetospeed.

R26 59.2 3182 10 SD 18.1
R26 59 3218 38 SD 9.7
R26 59.1 3221 38 SD 5.8
R26 59 3221 63 SD 13.1


H1000 60 3176 10 5.6
H1000 60 3205 38 7.0
H1000 60 3210 38 3.1

N570 61.9 3194 10 9.7
N570 61.9 3197 38 12.8
N570 61.9 3208 38 13.2
N570 61.9 3221 63 7.8

 

[Rhovee]

Great info. Interesting that H1000 was almost 1 FPS per degree. I wouldn't of guessed that.

 

[Bravo 4]

I wonder if/how load density and chamber pressure effect this? Can it have an effect on temp sensitivity?

 

[parshal]

The N570 load is compressed in my above loads. I was surprised how little it changed from 10 to 38. I'm not sure I trust the R26 results. It's been my general impression in my 22 Creed that it shifts much more than what the above results show in my 6.5 SS. I'll be doing more testing with the above loads over the summer.

 

[jpndave]

I wonder if/how load density and chamber pressure effect this? Can it have an effect on temp sensitivity?

These are good points. I haven't had a chance to test loads and temperature yet but my concerns are at temperatures above 70-80 degrees does the pressure change stay linear or go more exponential? Load density and higher temperature might make things run away on pressures.

I'd like to look at RL26 and Superformance for 6 Creedmoor, 6.5 Creedmoor and 7 WSM but my shooting conditions can vary from freezing to near 100. The extreme powders are probably a "safer" bet but these newer multi based powders like RL26 sure seem to be a lot more effecient.

I appreciate everyone posting results here.

 

[Wedgy]

my concerns are at temperatures above 70-80 degrees does the pressure change stay linear or go more exponential? .

I have found both RL26 & 33 rise exponentially above ~83F. It gets well over 100F here out West for extended periods and I have found that I cannot use them during the summer as they push my loads to where they are dangerous as I am riding the top node. H4350 & H1000 stay linear above 100F for me.

 

[jpndave]

I have found both RL26 & 33 rise exponentially above ~83F. It gets well over 100F here out West for extended periods and I have found that I cannot use them during the summer as they push my loads to where they are dangerous as I am riding the top node. H4350 & H1000 stay linear above 100F for me.

That's what I was afraid of. I may have to play with some other powders. If you are consistent on temps or stay under 80 it sounds like the variance isn't that bad. Over that, bad news or low nodes which kind of defeats the point. Just as well stay with the other stable temp stable powders where the high node is consistently safe.

 

[coop2564]

I have found both RL26 & 33 rise exponentially above ~83F. It gets well over 100F here out West for extended periods and I have found that I cannot use them during the summer as they push my loads to where they are dangerous as I am riding the top node. H4350 & H1000 stay linear above 100F for me.

I have not found this at all. I've been shooting in 100+ degrees for 2 months now. My ES and SD is better in warmer weather, I do get some velocity and pressure increase but not any more than retumbo or H4831sc. I've had a avg velocity of 2838fps at 40 degrees and 2872 fps at 103 degrees. H4350 in that same temp range increased 23fps compared to 34 with rl26. I did get slightly better ES with H4350 at lower temps but near 100 they are very close to same in my gun. I've had no spikes or crazy things happen when shooting above 85 degrees. Any powder if you work up a max load at 30 degrees and switch to shooting in 100 degrees is likely to pop a primer or show Pressure sign. So I load for max temp and the little loss in cooler temps is still way faster than H4350 which means flatter and more energy, provided they both shoot roughly same groups. I cant speak to what RL26 does much lower temps than 40 it just doesn't get real cold in TX, my part any way. I also cant say what might happen if I had loaded up near max in cold weather and tried it in hot weather, but that no doubt is where this spike talk comes from. But 85% or more of the powders out there will do same. I'm running .53=1fps in my gun over my normal hunting temps, but it seems the gun must make a lot of difference for all powders because everyone seems to come up with different numbers. I put .53 in my ballistic program and I ring steel out to 700 everytime I go no matter the temp.

 

[Bowfishn]

Coop is that in your 6.5 CM?

 

[coop2564]

Coop is that in your 6.5 CM?

Yes 22" Bergara HMR. The great thing with this gun is it shoots EVERYTHING well. So far it doesn't seem to matter velocity and nodes have little effect. .5 or slightly better is what it shoots, when I do my part. On the down side I cannot get one hole groups with it yet. But with this load 47gr. 143ELD-X I get .4 to .5 moa and two weeks ago in 103 degrees also shot 1.5" 500yd group. This gun is by far my favorite, nothing seems to effect its accuracy. Most my other guns loads make a big difference, they can go from one hole to 2" and temp changes can affect their grouping. Not this HMR I just love it.

 

[Kerryt38]

I use Varget in my 6.5x47 and if I have the ammo in the sun when it's 85* out it will hit 1-1.5 MIL high at 750yards and it's billed as the most temperature stable powder out there.

 

[moosekiller99]

Yes 22" Bergara HMR. The great thing with this gun is it shoots EVERYTHING well. So far it doesn't seem to matter velocity and nodes have little effect. .5 or slightly better is what it shoots, when I do my part. On the down side I cannot get one hole groups with it yet. But with this load 47gr. 143ELD-X I get .4 to .5 moa and two weeks ago in 103 degrees also shot 1.5" 500yd group. This gun is by far my favorite, nothing seems to effect its accuracy. Most my other guns loads make a big difference, they can go from one hole to 2" and temp changes can affect their grouping. Not this HMR I just love it.

I've been experiencing the same thing with myHMR. Must have been built in sequence and not on a Monday morning or Friday afternoon. Here's a 3 shot group I shot during early load development.

 

[Blue Ridge Rifleman]

Tag

 

[Laguna Freak]

I've seen similar results online for RL16. They've got a couple good temp stable powders for sure