i have a dedicated floor model drill press....with a nylon brush jocked up in it....i feed it steel wool and i actually polish the inside of my necks,,,,,then blow out any residual carbon and steel wool and media with compressed air.....this helps keep the SD's in single digits also.
I have been using dry graphite to lube the bullet before seating. Seems to work quite well. Sinclair has this great product from Imperial that does this with no mess. Here is the link to it http://www.sinclairintl.com/product/9136/s
When I'm really obsessing about it, I do what Boltripper does. Then I lube the inside with a bore brush to apply Boron Nitride. I hate wet lube on the inside; damned powder sticks and annoys the shit out of me.
Some fine hand loaders remove the sizer button.
I polish mine with 400 grit sand paper with the stem chucked in a drill / screwdriver, then with micro fiber cloth and flitz. Talk about smooth. Repeat as the sizer needs it.
Carbon fouling in the neck is a constant.
Time is better spent throwing in a polisher before sizing.
Inspect cases while lubing.
Ultrasonic can remove the "dirt" but not quickly.
(send pm if you want to know more about ultrasonic)