I've had very good results with RL 19 in 6.5x55 with 100 to 160 gr bullets. I use it in coastal California, so extreme low temperatures really are not an issue. Honestly, I can't say that I've ever, in my limited experience, observed a temperature effect due to a sensitive powder with any cartridge.
I could get along with H4350 if I had to, but I hope they keep making RL 19.
Good shooting!
