i used bore butter,oh,for 35 years. got my 2 new hawkins tc .50 cal in 1971.never saw any rust. NOW,you guys scared me out of bore butter, so i am using shaeth for storage only. i use bb or crisco for my maxi-balls or patch lube on rb.i also still swab barrel with bb at start of shooting rb.i just dont use it to store anymore.at our beretta shotgun shoots only 1 lube is used. BREAKFREE.but this is shotguns not blackpowder.i still like bore butter for pushing a tight patch and ball down barrel and will continue to use it or crisco.