I read an article somewhere in he past that David Tubb seats his bullets long, and just before a match he seats them to spec, to negate the welding effect. I belive their is something to this. I always run a brass or nylon brush into the case necks because I thought it was easier on the die. With the Forster sizing die for my 6 Dasher I don't use the expander ball, so this spring I am going to experiment cleaned versus not cleaned. Luckus