The OP seems to have stopped participating. But, the question I have is most modern firearm designs do not allow a trigger to release a striker, firing pin, or hammer without the bolt/slide being completely in battery. Most of the time the design incorporates physical interference of the bolt or slide that keeps the trigger from releasing the sear or striker. Does anyone know of a modern gun that can be fired out of battery?

I agree it would be hard for me as a layman to mechanical failure analysis to determine cause. If I had a similar claim against a gun or ammo manufacturer I’d copy both the firearm and ammo manufacturer on the same letter describing the failure-with photos of both the firearm and ammo. I’d include, to the extent the pieces exist or could be recovered, photos of the shell case, lot number, firearm and pieces, SN of the firearm. I’d send registered return receipt and ask for a response within 10 days.