ORIGINAL: BGfisher
Could be your arrows are on the verge of being underspined. I know what the charts say, but sometimes tyhey don't keep up with the cam changes. Try dropping the weight down about 1 turn and see if that helps. If it doesn't then you can always turn it back up. If it helps then you either need to shoot at a lower weight for that shaft or get some 340's.
What he said. It's better to shoot a broadhead on a slightly stiff spine than a slightly weak one.