Too much run out will affect accuracy. How do you know when rifle dies are worn out? Resizer or seating die???? I shoot 308 (M1A), 30-06 (M1), 223 (ARs) and 300 Win Mag (bolt gun). I trim all cases first with Dillon case trimmers which resizes brass as well. Then I resize (again) and remove old primers with RCBS dies. Except for the 308, all brass is resized with FL. The 308 is SB. With exception of the 308s, and 300 Win Mag resizing, all expansion balls feel real sloppy when I bring expander ball back through bottle necks of 30-06 and 223. The balls are supposed to be carbide, but may not be and worn out???. All of my reloading manuals indicate that for proper die adjustment, I am supposed to lock the expander stem nut when expander ball exerts pressure passing through the bottle neck. This assures proper alignment. Military brass (308, 223 and 30-06(if you can find any)) do provide a lot more resistance when ball passes, but I shoot mostly commercial Winchester brass and some Remington in my firearms. I assume military stuff has greater neck thickness. RCBS indicated that they have experienced this type sloppiness before and for me to not be alarmed over this phenomena. But what about accuracy problems? I have an M1 and a bull barreled AR that consistency give me fliers which I am hoping to eliminate. I just ordered a Hornady concentricity testing device. If the 308 and 223 dies are just worn out, I'd replace. Anyone out there had this problem and found a solution. Or, is there another problem that I am unaware of??????