Stan;
This is just my personal opinion with nothing scientific to back it up. I would want to know what the bore diameter was & what the end of chamber diameter was. "IF" the amount of the step is greater than the thickness of the wall of the hull I would not want to risk shooting it. The case of a chamber with a sharp step is one place I would definitely recommend cutting a proper cone.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra