Okay, I plead ignorance of Hornady Custom Grade New Dimension 4-Die Sets. In the box my set came with, there is a, for lack of a better term, plug. It is not mentioned in the worthless manual that came with the set. Its suspiciously .448" in diameter, no taper and one end had a larger diameter (.492) head that could serve as an insertion stop. The ends are quite sharply edged, so I can't imagine it being an expander as it would be shaving brass the whole way. It makes me think it would substitute for the seating die conical bullet plug for seating flat nosed bullets. For as much as it cost, you think Hornady could have included an applicable manual for it. Anyone know if it was supposed to be in there and if so, what it does? It was lying loose, outside the other dies. The expander die already has an expander/flaring plug in it. I can provide a picture if it doesn't ring a bell. I reload for about 15 calibers, both rifle and pistol and have never seen anything like it.
Thanks,
Hoot