Powder temp sensitivity

I've tested i m r Hodgdon Ramshot All i ant powders here in Arizona for temp stability. Shot from twenty degrees to 110 degrees. Chilled the ammo baked the ammo and chamber. Got 150 FPS change with i m r from winter to summer. It locked the bolt on the rifle. Allian t was 80 FPS Hodgdon was 15 FPS Ramshot was 25 fps. Here I work up loads in winter at about twenty to seventy degrees. Then shoot the same load in summer at 110 degrees. Then hunt in the fall from twenty to 90 degrees. That's why I use and recommend Hodgdon and Ramshot powders. I have minimal velocity shifts with these two powder manufacturers.
 
I live in Arizona and hunt elk in Montana. My load development is in Arizona some times in 100 degree temperatures. I developed a load for my .300WSM using RL17. When I shot the rifle in 40 degree temperatures in Montana, I was surprised at the impact difference at 100 yds. I zeroed the rifle, but was uncomfortable with what the drop would be at 500+ yards. After that experience I did some research and tried RL16. I had much different results when I checked my rifle in Montana. There was a slight change, but I attributed that to altitude difference (+3500').
 
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