kilnbux , I shoot 28"s at 60 lbs , a 28 inch 400 spine beman matrix shaft , around 400 grains with 5" feathers and a 100 grain muzzy . Im not 100 % on the centershot as Im at work and the bows home , but I believe its very close to 1" . The bow shoots around 260 fps + .

Two other things I thought of that may help you are
1 Make sure you are useing enough fletching , I like 3 , 5" feathers or 4 , 4" feathers , and
2 Bottom out both limb bolts , and take one turn out of the bottom limb and see if that helps .