i was that shooter of that exploded rifle, i was using factory ammo and it was a national ordnance.
hey, how was i being a smart arse? lol
the cause of the case head seperation was due to improper headspace which was caused by the softness of the receiver. the front and rear locking lugs started to indent from pressure of being fired which lead to excessive headspace.
I'm just happy you're alright!
BE CAREFUL and always use hearing/eye protection OK?