Received a reply from RCBS yesterday. They're sending me a new plug. They said it could be tooling marks on the inside or the Ogive of my bullet causing it.. The rep also explained that RCBS plugs are designed based off of Speer bullets... The Ogive theory could explain why the 87gr Vmax bullets didn't stick but the longer 103gr ELD X did.
So as an experiment, I filled the hole partially with Waterweld epoxy. As it was beginning to set, I inserted a bullet to form the epoxy. A few minutes later it was set and I went over it with some fine grit sandpaper. I was able to seat bullets with no issues after that.
So as an experiment, I filled the hole partially with Waterweld epoxy. As it was beginning to set, I inserted a bullet to form the epoxy. A few minutes later it was set and I went over it with some fine grit sandpaper. I was able to seat bullets with no issues after that.