While it's always a good idea to check the spent cases, very few people that don't reload do that. Also, I'm pretty sure he clearly stated that the one that blew the original gun was the first shot out of a new package of ammo. The ammo in the original video clearly did not exhibit the same overpressure signs that most of the remaining rounds from that package fired in this video did as there was no difficulty removing the cap or the spent cases in the first video prior to the detonation."Freak accident"....No.
He never stopped and looked at the fired cases in the original incident. Watching the video he just threw them on the ground. Even when there was a significant sound/recoil difference from a normal round.
This new video doesn't really prove anything to me. How about disassembling one of the SLAP rounds? see what it is loaded with. Blowing up an expensive gun never impressed me other than a manufacturer under controlled conditions for testing reasons. There were no scientific controls applied in this video.
Sorry, just not impressed.
Don
It should also be noted that none of the other remaining, clearly overpressure rounds in that package were able to blow the gun, the gun did not blow until he fired a round specifically loaded to blow the gun. It would have been nice had he fired the remaining rounds in a ballistics lab with the use of a strain gauge but that's not a realistic expectation and the demonstration he did conduct was more than enough to support the conclusion that he drew. It was absolutely a freak accident.