i'm still new at bowhunting so bare with me.......i'm getting some red head carbon supreme arrows.......i have 27 draw length back last bow season....my bow is set at 56 pound........what grain per inch do i need to get on my arrows.........they have three sizes shaft size 150...grains per inch 8.4...........shaft size 250 ...grains per inch 9.5.............shaft size 350......grains per inch 10.7 what arrow do i need to get........i'm going to be shooting 100 grain broadheads..........need help.........