That's impressive, I've seen a number of No4's which were over pressured and they were not fireable afterwards.
In 3 cases, I've seen the front of the bolt "dolphined" out of the action - i suppose the bolt body stayed straight, while the action bent down.
Unknown what loadings were being used but the 1 fellow claimed Canadian7.62 ball (it was a modified DCRA 7.62).
I wonder if the scope helped in this (L42) case?