Hi folks, new to Campfire. Been reloading for 30+ years. Hopefully I can share some useful info.
I have reloaded for 3 different 26 Nosler's (Cooper, LAW and Hill Country). As you probably already know this cartridge can be finicky with regards to pressure so please proceed with caution as every rifle is different.
With regards to IMR 8133 and using it for a 26 Nosler, I windowed my Hill Country from 75 grains up to 77.5 Grains using a Barnes 127 Grain LRX and FED215M primers. Nosler Brass. Best groups were on the low end of the window (.34" & .37") at 100 yards. I do plan to spend more time with some other bullets using this powder.
US869 is my go to powder in this cartridge and seems to provide the most consistent results across various rifles and bullet combinations.