I added about 6 ounces of lead shot to the rear of the buttstock on my 835, to calm down the recoil and did not notice any POA/POI problem. It did help balance the gun though. The gun was nose heavy but with the added weight, it moved the CG to the rear. Did you just pour the shot in? I used a sock taped with duct tape, filled the hollow portion of the stock with Styrofoam trimmed to fit and added the duct taped sock at the very back and reinstalled the recoil pad.