I personally believe that some of these issues have come from not getting the proper tension on the stock to mounting stud screws they should be torqued to 28 inch pounds to loose or to tight will create problems on most of the plastic stocks used to day; It really helps keep the same POI irregardless of what kind of stock you use, I do it on all my guns.Not holding it solid or to much stress can spoil the guns abailty to group I suspect these kind of problems when some one can not get groups under 2 inches. Lee