05-05-2022, 01:53 PM
grayfox Wrote:Found a study from Aug 2021, looking at powders for Service rifle competition. While it is for 223, it also shows some useful info on temperature behavior for some powders we use.
AR comp, varget, H335, CFE223, 8208, and H4895.
Temperature Sensitivity of Powders for .223 High Power Service Rifle (wlcastleman.com)
I would also note that the study is for the 223 cartridge, and my belief is that powder temperature sensitivity also can vary by cartridge, "fat" vs "thin" cases (ie, the nature of the powder column you have to burn), large vs smaller capacities, type of primer used. But it still provides some info. Particularly for the 77 gr bullet, as it is closer to our weights vs the 55.
Couple of takeaways I think I saw last night:
CFE is somewhat but not too sensitive from 68-32 deg, it is much more so for the higher temps.
AR comp actually increased MV as temp went down from 68-32 deg, which is a switch.
8208 fairly flat from 68-32 deg.
I zeroed in on the 68-32 part of the range b/c that's where I do most of my hunting, I don't normally go out when it's blazing hot or sub-zero.
Wish they had gone from 90-32. I hunt like you in the 68-32 range, but load development is in the off season where 80-90 degrees is common.