I have tried several other bullets in my 300ultramags and only the sciroccos caused severe copper deposits.No other bullet showed any substancial copper deposits at all.However the standard x bullet showed similar copper buildup in my 7mmstw's.Accuracy was also horrible with the sciroccos in both rifles with both 165 and 180gr weights.Goups ran in excess of 1-1/2" while the tsx's average 3/4" and the ballistic tips even better.