My reply...
Many years ago I saw a picture of a revolver similarly destroyed (I think it was in precision shooting, but I could be wrong). The conclusion was that the powder used didn't fill the case. When the gun was leveled to fire, the powder flowed forward. If you can picture the powder in a case laying on its side, the level of the powder was lower than the primer hole. The primer fired igniting the entire charge at once, rather than from one end. The force of the explosion was directed upwards, removing the top half of the cylinder and the top strap of the gun. Their answer was to mix oatmeal in with the powder to fill the case and shake the cases to distribute.
I haven't reloaded in a long time, so I don't know whether this would be an issue with this load. Or, you might have gotten a short powder charge in this one case.
Always reloads...