I am in the process of load developing for a model 700 in 300 Win Mag. I can get a 0.4 inch group at 100 yards with the Sierra 180 grain Pro Hunter, flat base. I have tried work up loads with Accubonds and Scirroco II's and can't get a group smaller than about 1-1/4". Some of these boattail loads fly all over the place. Has anyone had a problem similiar to this where flat base bullets group very well and boattails don't?