is a case failure due to a particular point on the case, which just happens to line up with the unsuported part of the barrel, or is it the entire circumference of the case and any part would fail where unsupported. If the former is true, could it fail at any point on the circumference of the case? If so, could a case failure occuring somewhere other than the unsupported part cause a Kb? If the latter is true, then I see the point, "a case failure is not a Kb."
Just don't know how case failures occur.