Kinda of crazy. I have a set of new Redding 300 PRC dies that I can't get the casing to go into but about 1/2 the case. I cleaned the new die and lubed the case with imperial wax and it went about 1/2 way. This was a once fired case. I then took the decapping pin out and lubed it up again and it would only go about 1/2 again. The once fired case was a Hornady case. I then went a got a new piece of Lapua brass and it went in about 3/4 of the way with the decapping pin out. It has me puzzled as well.