Got some N570 temp data today from my 300 RUM 227 grain HH 3,005 fps 5 shot ES of 14 previous load was 91.0 grains WLRM primer, took an elk at 987 yards a season ago but I started a new lot of primers and the velocity picked up about 50 fps and the ES went way up, could be the barrel speeding up too but 215M brought the ES way down so I switched to those. It's hot here(over 100F) so I put some in the cooler and shot some at ambient temp measured with a Hong Kong Freight laser thermometer and shot at 500 yards, the TT 5-25x handled the mirage pretty well. Three to five minutes between shots running a barrel fan to help cool it.
Top left 90.5 at 38F 3,051 3,052, 3,048 average 3,050
Top right 90.1 at 38F 3,070 3,061 3,059 3,063
Bottom left 90.5 at 94F 3,087 3,066 3,095 ejector 3,083 56F = + 33FPS
Bottom right 91.0 at 96F 3,126 big fat ejector, stopped 3,126 58F = + 63 fps
It has been very accurate and easy on brass at the ~3,000 speed so I'm going to go lower to get back there, 91 grains is a full case, slight crunch at just under 4" COAL. Looks like it's going to be 100F here for the next week so I will bring the cooler again as it seems I'm always hunting elk in the snow.
Most powders are temp stable until they get to the higher temperatures then they really shoot up in pressure , N570 isn't wicked but it isn't H1000 for sure, this is the first I've I've shot it over 82F and the biggest jump I have seen and it may do better with less than a full case.
FYI
View attachment 379468