I am wondering about powders for a 500AccRel class of cartridge (and 500MDM), whether 'light' 450 grain bullets or heavier 570 bullets. (Charges may run around 90-100 grains). Experience at smaller volumes would also be appreciated.

What have experiences been with Hodgdon's Varget or the recently released Leverevolution?

The Varget is part of the "Extreme" line, which means that it is advertised as relatively temperature insensitive.

The Leverevolution is part of the Superperformance Hodgdon line of powder and ammunition.

Does anyone have comments about this latter's stability in varying temperatures or in cases much larger than the level rifles it is advertized for? The burning speed chart puts it in the same range with Rel15 and Varget.

Any help and experience is appreciated.