Check your scope and mounts - make sure all is secure. Check your barrel's crown to see if there is any damage and make sure there's nothing strange going on there. Make sure the action is secure in the stock.

Are you swabbing after each shot? I would.Are those sabots easy to load or do they go down pretty snug?

Your results at 200 are not at all what they should have been. Something is wrong... either the scope shifted or is failing, the crown was damaged, a gross shift of the barreled action in the stock, the loads were somehow changed (volume measure moved?), or you are pulling those shots down.

Shoot again at 100 yards first to see if your results there are not also much lower. If you can't figure out what is causing this, try a different bullet.