I've polished every expander ball I own. The biggest problem I had was on the upstroke so a tapered ball wont do much for that. I spin them in a drill press & using 600 grit wet/dry paper move up & down as possible concentrating on polishing the major diameter & rounding the edge opposite the decapping pin hole until it shines like a mirror. Some older dies required a few touches with a very fine file to get the shape right before polishing. There has been a noticeable difference in the amount of grating & drag when pulling it back through then neck.... Same here.
"The Democrat Party looks like Titanic survivors. Partying and celebrating one moment, and huddled in lifeboats freezing the next". Hatari 2017
"Hokey religions and ancient weapons are no match for a good blaster at your side, kid." Han Solo
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