I must be lucky, My 116 300 win shoots the same impact, with a clean cold bore, cold dirty bore or warm dirty bore. I did bed the action and I do turn the necks on all my brass, and I am shooting Berger Vld's and 4831Sc powder. but it prints the shots the same spot no matter what condition the bore is in. I usually clean it about once every other week or so, But I do shoot ALOT. It shoots 3 inch groups at 600 and can usually hit a milk jug filled with water the 1st shot at 800 yards if I do my part right.