Prototype set is here

[miniman82]

Right, the fracture can tell you a lot about how the failure manifested. I actually used to do a lot of that kind of thing in aviation, since I was part of an emergency reclamation team. It looks to me like it began right at the top where the heat was at its strongest, then propagated around the rest of the neck. I will send pictures to Filipe later this week, asking his opinion.