My 26" 6x284 with 10" twist loves 60.5 grs of Magpro behind a 87gr V-max.(3,617to3,644) With a lesser weight charge ( 57gr)of IMR 7828 ( Slower burning and with Magnum primer) had a velocity spread from 3,568 to 3,678 with tight but verticle string group at 100 as with Mag Pro is was a tight round group. I wonder how H1000 would do?