Just one more observation: In my recent tests the Alliant Reloder powders have been better in cold than in the past.
Besides Alliant, I've been wondering whether St. Marks has been making adjustments to some of their powders also based on some testing my brother did this year. Though his testing didn't go down to sub-zero, he tested across a range of 70-80 degrees. In his 308 Win, he found 748 to vary only ~1/3 as far as Varget did behind 150s.
It's been about as cold here as there where all you Montanans are recently, but I haven't loaded any more 748 up in my .223s to test. I did test some N-133 a couple days ago, and it lost ~100 fps from 75 down to 5 degrees.
