I have .270 win brass, once fired with light load(56.5) of h4831 and no problems. However, the second time after firing it I noticed what seemed to be a crinkle(not a crack, but kind of looks like a crack) on the top side of the expander ring but only on one side of the cases. The load was 59.5gr of Re22 with a federal 215 and a 130 sierra. There were no other signs of pressure, cratered primers, extactor marks, etc. I am also using forster bench rest neck sizer dies. The gun is a model 70 featherweight. Any idea what would be causing this? Thanks, A.J.