Both of the above have happened to me. On the seater plug I put some course valve compound on a bullet chucked in an electric drill, then followed up with fine compound and then Flitz.
The crimper on RCBS dies have given me fits when I over adjusted them. I have even buckled case necks due to operator error.
A dirty die will also do this.
"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli
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