So stupid... We all know not to reload while distracted, how dangerous that can be. The same holds for tinkering and anything else. I feel stupid. At least what I did wasn't dangerous; I just turned a useful tool into scrap metal.
I've gone to powder coating and push-through sizers, and getting away completely from lube-sizing. I have Lee sizers for most calibers I load, except a couple. I'm really cheap and have just been picking them up when I find them cheap. I need one for Makarov bullets, but Lee doesn't make a .366" sizer. I found a cheap used .357" one at a show a couple days ago, and have been carefully honing it out with a rod and sandpaper.
I've had some very frustrating, discouraging days at work lately, and that's been on my mind a lot. My mind was wandering as I patiently rolled the sizer back and forth, stopping to measure every so often. Finally it was about a half-thousandth from where I wanted it, so I switched sandpaper to 600 grit to finish it.
Only I inadvertently used 320 grit, a nice fresh, sharp piece. I sat there rolling it back and forth, thinking about all my troubles, forgetting to even stop and measure. Now I have a very nice, polished, push-through sizer that measures a very concentric .3685".
Oh well. I spent a lot of time making a piece of scrap. At least it didn't cost much. I think I bruised my ego more than anything. I like to think I'm very careful and precise maybe not so much. :/