I recently put Schmidt and Bender 1.5-6 X 42 scope on my Sako .375 H&H. The scope is mounted with Sako's quick release rings. Scope is 30mm in diameter and rings are sized accordingly. Alignment is good and set-up shoots well.
The problem I had both times since shooting this set-up is that the scope keeps getting driven backwards in the rings after repeated firings. Naturally, the first question is are the rings tight and I'd have to answer yes. There are 4, 2.5 mm socket head screws on each ring. From what I can tell I'm tightening them down evenly using a properly sized allen wrench to the point that I'm afraid to tighten them any further, i.e., damaging a screw, bending the wrench or damaging the scope barrel itself. When this happened the first time I simply thought that I had not tightened them enough initially so before going out the second time I loosened everything up and slid the scope forward in the rings and really cranked them down. However, much to my disappointment after about 15 rounds the scope was once again moving backwards in the rings. I don't have much room to play with, perhaps 2-3mm of the scope's barrel length in the quick release mounts before the variable adjustment ring wedges itself into the scopes mount, therefore it needs to stay in place.
I have never experienced this with any other scopes I've mounted so I'm wondering if anyone has any ideas for me to try.