I hunt mine using 77 weighed grains of bh209 powder [110 grains by volume], a black crush rib sabot and a 300 grain .451-452 XTP bullet. Winchester blue box 209 shotshell primer. Accuracy started to come together at 63 weighed grains [90 grains by volume] so I'd say star somewhere in the 63 grain weighed range and work up from there. The Impact breech plug in mine needs to have the flame channel right behind the primer pocket cleaned with a drill bit after 10-12 shots for reliability.