Remington and others vent it sideways in the area of the bolt/lug cavity behind the breech. Not all rifles are the same, of course. Weatherby vents gas sideways thru the bolt.
If this rifle is in limbo in the legal department they're taking way too much time for your situation.
If there are numerous situations of the same problem, which means an engineering fix and tests have to occur, possibly a recall. We don't know what is going on there, admittedely, but the silence is concerning.
No excuse to not communicate status and send you $ or an upgraded rifle option if there is a product safety issue, using ammo that cannot contain the pressure. I'm hearing split brass on this cartridge is happening with some frequency. That's a contributing factor if not "the" factor. Your photos bear that out.
In my engineering experience, dumping high pressure hot gas into plastic components (in a dead headed pressure situation) containing ammunition is a questionable practice. The results spoke in your situation, whether or not your mag had ammo in it. The HMR cartridge obviously had enough pressure to disintegrate the parts and sling them 50 feet. I don't think the Remington and Weatherby gas path designs would have allowed this. I've pierced primers in my reloading and gas vented safely away, on the Remington.