does anyone know of a good temperature resistant powder that would work for a 220swift,55grn @ 3600-3800fps) and also work for a 243 Winchester,75 grn @ 3300-3500 fps) .Varget works in the 243 with the 75 but i have only loaded it for my 22-250 not my swift.Time at my range seems to be harder and harder to find so any suggestions will help.
Thanks.
Thanks.