1- ensure the optics are mounted correctly.
2- are the optics of reasonable quality?
3- is the mount correctly installed?
I would be very suspect of the condition of the stock/mounting points. Frequently the stocks are so oil soaked and generally crappy that you cannot get the action or triggerplate to stock fit correct. If this is happening the action is dancing around in the stock and there goes any chance of hitting what you are aiming at.
If the stock is in reasonable shape you will benefit huge from pillar bedding otherwise just buy another stock.