I have a new savage m12 br in 6mm norma. The chamber has the worst chatter marks on the shoulder. New lapua brass has generated good groups(5 shots .180 to mostly in the .3's). I have a return label to send it back to Savage to clean up the chamber or rebarrel. Im afraid they will send it back worse than what I have now. Should I leave well enough alone or roll the dice and hope for improvement in accuracy with a smooth chamber.