Some of the once fired .223 LC brass I'm reloading for an AR-15 does not easily go into a Lee shell holder. I haven't looked closely to see what about the extractor groove on the case is deformed. So far, I'm just forcing it into the holder and working at it to remove the shell afterwards. Should I be just discarding those cases that don't go into the holder smoothly? Is there any operation that some people perform on their brass to "clean up" the groove?