I read in a magazine that an aluminum rod can damage a barrel while cleaning. How could this be possible since aluminum is lot softer than steel and that the rubbing force are may be a million time less than the force made by a single bullet ( wich is at first more hard than the cleaning rod) shot at great speed. When two metals of different hardness rubb against each other, the softer one will wear out, not the harder one, like in a bushing. From what i have read until now thre are different shools of tought concerning this. What do you guys think of it???