I have put well over 2500 rounds thru 300RUM's, three of em. One BDL, one PSS, and one I had built, and I used Leupold bases and rings on all of them. Can't say I ever had that happen. Only way it can happen is if it got loose. Especially if you only stripped one base. That tells you something. It shouldn't have only stripped one base.

When you installed them, did you degrease the screw holes and screws and locktight (blue)them down. Worse thing that can happen is when a screw is not tight and the base is able to move around.Also did you lap the rings for even distribution of the mount.

Now, the one problem I did have with the 300RUM's is I couldn't keep the scope from moving in the rings. Only way I could hold the scope was to lap the rings (ring lapping kit), until I had 100% contact. Takes me about 3 hours to do a good lapping job. Finally that held the scope in place.