No matter what you chamber, short of blowing up the cartridge and blowing the magazine out of the well, the magazine has nothing to do with case pressure. The magazine will limit the COAL but the bolt will not fully close long before the cartridge won't feed, great thing about a bolt action.
Your issue is mechanical in nature. It will either be the retention spring, the release arm or the indent/protrusion on the magazine itself.
I had a similar issue with a Ruger and it turned out to be the release arm, the locking end became rounded a bit and allowed the magazine to come loose.
I replaced the release arm (on the Ruger) but I imagine it is possible to square it again. In my case the arm was cheap enough to just replace.
Good luck and don't loose small parts. I'm good for having springs and such mysteriously vanish......