R-25 temperature variation

[Cheyenne 1]

I was just started making some loads for my newest rifle. A remington 700 in 257stw. Using remington brass, CCI magum primers and RL-25. Started out with 77 grns, ended up at 81. Problem seems to be with the larger powder charges are really sensitive to temperature change. It is a little cold here, about 14F.
I didn't think the last couple of loads were what they should be. I put the last 2 in my pocket to warm them up and both were exactly the same speed 3875, the ones before at outside temp were at 3760. That seems like way too much of a spread.
I have read (Now) that the r-25 will do this. Anybody else have this problem? What about the Hodgon extreme powders, they claim that it will not change with temperature?
Where I hunt it can go from 50F to 40 below 0.
Thanks

[jayran]

I use rl25 in my 257 wthby accumark tried the same thing but didnt experience the problem. I had read the same thing so had to try, from what i remember thru the chrono i didnt see more than 40fps. I will have to try it again, because I was just reading another post with similar concerns???

[royinidaho]

With RL-22 in a lowly 270 Win I dropped from 3200 MV @ 70* to 3070 @ 15*. (130 FPS)

The RL powders are quite temperature sensitive.

I'm not bothered by the temp sens. as long as I know how much its worth.
BTW all powders are temperature sensitive, some more than others.

[Len Backus]

Roy, I wonder if that much velocity and pressure difference changes barrel harmonics and therefor POI or even group size.

[Derek M.]

Originally Posted by Len Backus

Roy, I wonder if that much velocity and pressure difference changes barrel harmonics and therefor POI or even group size.

It did not in my 300 RUM. I worked up loads in Ohio during late summer when it was about 80-85 degrees and hunted in Wyoming and Colorado when it was in the 20s and 30s. Granted, I didn't shoot far (under 400 yards), but the bullets hit where I wanted them to.

Hodgdon Extreme gets the nod from the bulk of reloaders for temp concerns where highly suspect powders like Alliant lose their luster due to repeated experiences of temp sensitivity.

My solution is to work up loads during the time of year that will be on par with the climate I plan on hunting. Fortunately, I do this here in Ohio where it can get just as cold as it does when and where I hunt out west. So far, problem solved.

Reloder powders produce some of the most consistent and best groups I've ever had, not to mention best velocities. No way I'm not going to use them any longer like a lot of guys do when they ultimately narrow down all choices to Hodgdon.

[Derek M.]

Originally Posted by royinidaho

With RL-22 in a lowly 270 Win I dropped from 3200 MV @ 70* to 3070 @ 15*. (130 FPS)

The RL powders are quite temperature sensitive.

I'm not bothered by the temp sens. as long as I know how much its worth.
BTW all powders are temperature sensitive, some more than others.

I think I'm going to migrate to all magnum primers in my 270s. I have good loads with both 210M and 215M and I'm thinking (could be wrong), that a hotter fire to start could reduce velocity changes.

I think a 215M might be the ticket with the slower powders I use such as Re22, and H1000.

[royinidaho]

Originally Posted by Len Backus

Roy, I wonder if that much velocity and pressure difference changes barrel harmonics and therefor POI or even group size.

Len,

You betcha on all of the above.

The good thing is that for my use the Winny is relegated to less than 300 yard opportunities in the winter. For yotes and mule deer in the back yard area shot distances are nearly point blank, if I'm stealthy.

Derek M.,

I agree. Especially when shot opportunity is under the 400 yard mark.