Re: RCBS expander ball
Unfortunately, yeah, that seems to be pretty normal. I've always looked at expander balls as necessary evils, at best. I prefer to use mandrels (like the Sinclair) whenever possible, with a carbide expander ball as a next best alternative. A polished carbon steel expander ball (like yours, after you've polished it) is the thrid choice, with an unpolished expander ball coming in dead last and a nearly unacceptable final option.
If you can't replace the ball with a carbide part, then it needs to be polished, at the very least. Very fine crocus cloth, 320-400 grit or so, is the stuff to use. remeber, you're not trying to alter the dimensions any more than you absolutely have to. You just want to "shine" it up a bit to make for easier passage or less drag during its passage through the sized neck.
Hope this helps, but if there's any questions, there's plenty of help right here on the boards.