I am reloading 160 grain bullets for my 7x57. An article in Hanloader magazine suggested H-4831 in cooler climates and RL 22 where temperatures are more "stable". Could someone explain? RL powders seem to give top velocity whilst keeping pressures safe and work very well in my .270 and 35gibbs. Is there a technical reason why they are less suitable for Northern Climates?
I know RL 19 is great in the .338mag so I imagine it's nothing --- just curious.