Whilst work hardening brass is an issue with HMR I think it is only fair to point out that I have experienced center fire ammunition issues.
I have not bought much factory ammo in my life, mostly reloaded. There was the one time a 222 factory round blew it's primer pocket with an almighty bang and a strange recoil impulse that had my ears ringing for days, a classic flame out circumstance. A friend had a similar thing from a 7mm Rem mag.
Another friend had his bolt stuck in his face from a detonated 6.5 Swede factory round.
It happens. That is why there are venting holes on most actions.
I agree HMR has suffered terribly but it all seemed to start around the late nineties and I often wonder how much of that bad ammo is still about?
It was only a couple of years ago that I bought hundreds of HMR ammunition from that period going cheap because of said issue.
I knew what to expect and as I used it up inspected it for cracks.
I still took any amount of vermin with it all near enough.
Still don't know what brand this happened to the op???