Re: Least Temperature Sensitive in 308Win?
You might try Reloder 15, since this is what is used in Lake City's M118LR ammo. They test it to some pretty severe temperature extremes for certification, for both heat and cold. Hodgdon's Varget is another that they advertise as being largely insensitive to temperature variations. Good stuff, and you'll certainly have no trouble developing accurate loads with either of these two.