RL 22 temp sensitive

[swampbuck]

I here all the time about some powders being temperature sensitive, particularly RL 22. I use RL 22 and IMR 4831 mostly. What kind of temp extremes does it take to see major inconsistencies or pressure spikes.
If I am shooting (sighting in) in 90+ degree summer and fall weather at long distances 400-500yds and then deer hunting in 20 to 30 degree mornings, what kind of effect, if any will it have on accuracy.

 

[R Flowers]

Powder sensitivity to temperature is a subject that is beat around a lot lately.

Hodgdon brags on their "Extreme" powder line and I believe that they are about the best for not changing with temperature. Same goes for Vihtavuorri powders. Those folks live in some damned cold climates and know how to make powder shoot the same no matter what.

I use RL 22 a lot and have really not seen any real problems. Like you, I shoot a lot in 90 or 100 or even 110 degree weather. (Then wind up hunting when it is 20 degrees.)
I have seen more problems with RL 22 with lot to lot variations than I have with temperature sensitivity.

On the other hand, I have, as of late, seen some real problems with IMR 4831. My dad and I both thought something was wrong with our chronographs as our 25-06 loads using IMR 4831 seemed awfully slow last winter. The groups were good, but the velocities were off a good deal.

So, I did an informal test on my own. I loaded some shells with various powders and put half of them in the freezer and left the other half at ambient temperature. The next day I pulled the ones from the freezer, put them in an ice chest with ice packs and hauled ass to the range.

I found that in a number of rifles Hodgdon powders either did not change much at all, or they actually gained velocity when cold. This is the second test I have done where H 4831 shot slightly faster after being frozen and kept cold than when at ambient temperature. Go figure !

Rl 22 lost about 25 fps in my 270 WSM when shot cold versus ambient temperature of about 90 degrees.

HOWEVER, on two different days I tested IMR 4831 in my 25-06 and the shells from the freezer and the ice chest lost nearly 100 fps compared to the ones stored at ambient temperature.

The groups were just as good as the warm shells, but the velocities of the cold shells was lower both days. So, you cannot say the accuracy drops off, but the bullet drop at long range would sure be different.

Very informal test, limited data, but enough to convince me.

 

[JD338]

I too have seen lot to lot variation with RL22.My loads have been developed in the summer months so I have not seen any pressure spikes in the fall or winter.

Good data research RF.

JD338

 

[steve4102]

Hey RF, I have run similar tests with Ramshot Hunter and BigGame(ball powders). I tested my loads the other way cold day and warmed up ammo. I did my test at -4*. This way I would not only have the ammo cold, but the rifle barrel as well. I kept the truck running with the rifle and ammo near the heater to keep them warm. Fired off several rounds with warm ammo and rifle and several rounds with cold ammo, rifle and fingers.
I don't have my test results in front of me, but I do remember that the velocity was only slightly less for the cold rounds/rifle and POI was unchanged. My group size for both warm and cold rounds was considerably larger than from the previous summer. I would attribute this to MY ability to shoot well under extreme conditions. Maybe the human factor is what is affecting others POI and groups size in cold temps and not so much the powder.

 

[Ol` Joe]

I too heard there was a sensitivity problem with R22 and temp extreems and ran a test of my own useing a pressure trace and Pact crono last winter/early summer. My findings are here............

http://www.24hourcampfire.com/ubbthread ... ost1460421

Remember though, this is only 1 test, with back yard equipment, and may or may not be a honest representation of the powders characteristics. A different cartridge or bullet wgt may alter things considerably. :|

 

[JD338]

Ol` Joe

Very interesting data. Thanks for sharing. 8)

JD338

 

[Bruce Mc]

I use reloder 22 a lot in my 7mm rem mag and my .257 roberts. I have noticed about 50 fps difference in season for the mag and around 40 for the bob. I work up my loads in the temperate regions of south texas, say 98 in the shade during the summer and I was getting 3300 fps with the 140 AccuBond. During the cooler times just before deer season, temps in the 70s, i got 3250 fps. The bob chronos at 3050 fps during the hot summer and 3010 fps just before season opened. It was around 70 again. Thats not really enough velocity to get churned up over. If I don't take my time and let the barrel settle after each shot, I can more velocity variation than that with H-4831 or H-1000. I wouldn't fret it.

That was some good stuff on that pressure trace.