I have a couple of M75's and I can say from experince that the one chambered in 375 H&H has dropped it's magazine from recoil alone.
That may explain why they made a limited edition CRF with a hinged floorplate for the V series actions that was chambered in 375. It was also pretty common to find a hinged floorplate along with a DM when finding a 5 Action and I believe if not mistaken that the RUMs came with hinged floorplates. The Biggest Sako action I owned was a 5 in STW and I never fired it. It came with a DM.