No matter the root cause of the failure, the photo evidence indicates the event involved extreme pressure at the chamber. I'm guessing the pressures were above where the Bell Parker blew.
Someone on the other bbs suggested the metal wasn't ductile enough. Sheeesh! Look at all the deformation and chamber swelling. Another suggested a pre-existing crack caused this. Then why all the deformation and that fracture face? Why the split reciever?
I agree with Dick that you can't conduct a failure analysis based on pics across the internet, but these things are evident in the pictures.
