bullcoon:
It would appear from the Hodgdon website that they are marketing the Australian ADI-manufactured powders as the new 'Extreme' range. All the ADI powders are made the same way as Varget, and share its temperature-insensitivity. I don't have the ADI/Hodgden equivalents to hand (lunch-hour at work!), but someone here will post them. There will be a more suitable powder for the Rigby in the 'Extreme' line, but that won't help you with your Varget glut!

Hodgdon 'Extreme' Powders

Cheers