I use RL19 almost exclusively in my 6.5x55 and it works great. I haven't noticed any difference in POI in my rifle at temperatures between about 40 and 90 F-- but then, I guess I shouldn't expect any. We just don't get cold enough temperatures here in Coastal Northern California for it to be an issue I think. I used a lot of IMR and other powders prior to the appearance of the temperature insensitive powders (e.g., Hodgdon Extremes and RL15). At Coastal California temperatures I never had any issues. That said, I frequently will use temperature insensitive powders now if they work well because, well, why not.
I've been very happy with RL19 in the 6.5x55, but less so in .30-06 where I like H4350 much better. Probably depends on your conditions, rifle, etc.
Good shooting!
