Looking at the photo of the breech in post #8 it looks to me as if the firing pin is centered on the extractor, and the imprint from the case is a lower circle than the circle which is the full diameter of the extractor hole. Also, the hole in the primer is off center as the firing pin is off center to the imprint.
In any case whether it is or isn't off center should be easy to see either way, as stated above.
Ragged, I asked that about not being a reload because of your previous postings in which you are clearly learning to reload for the .45 acp. So, if you are reloading why go to the expense of new ammo for this outing only?
This is certainly a mysterious happenstance, but it is one that could be accounted for by the type of things that occur when errors in primer seating or powder throwing take place during the reloading of ammunition.
If such a thing were the case it would not be a first in here, or the last, I'm afraid. I'm most afraid though in those cases where there is a denial of reloading error on the part of the person to whom the explosion (as it were) occured, because it's in those cases where it does not seem that learning to prevent a future occurance has been the benefit of the accident.
I'm just saying....