By the "I'm willing to assume blame for reloader error" comment, I assume the ammo in question was reloaded.
To me, this looks like an ammunition problem instead of a barrel metal integrity problem.
I would immediately condemn the ammo from that loading batch and ALL ammo subsequently reloaded in that facility since that date until the matter is resolved. The condemned ammo should be labeled and isolated from other ammo.
If I had to guess, I would speculate that: A. a much "faster" powder than normal somehow got into the reloading process, or B. that a greater than specified powder charge was somehow introduced into the case and the greater volume was not noticed during the initial and final crimp stages.
Was this ammo reloaded on a single stage machine or on a progressive machine?
