03-13-2022, 03:15 PM
Superformance is way too slow of a powder for ARC, even for heavier bullets. I'm surprised it works at all. You really need to be with one of the fast powders you see in the Hornady data. H322 would be my first try given its temp insensitivity, but finding it isn't easy. I've never tried LT 30 or 32 but they were made for light benchrest bullets and might be worth a try and they have been on the shelves.
#FJB