I had a partial case head separation using a 1.8oz buffer

[Fess]

Although slightly off topic, from a first glance it has appeared that the belts in many of the examples that I have seen are remarkably flat on their outside surface. They indeed often do look like the belts on belted magnum cases. This puzzles me since in my experience, bulges caused by pressure ted to be more rounded. Can anyone propose an explanation of why they are so flat.
Thanks.