my symptoms.......When I first started shooting this beast I quickly realized this was the most powerful and the most accurate rifle I have ever owned. Consistently grouping 5/16" center to center and often less. with a fixed ten lightweight scope, I switched to the heavy weight high magnification scope and things got even better.....for a little while.... and then things started to loosen up but only on occasion, it was sporadic and while my 100 yard zero only shifted a 1/2" elevation and then right back to where it was I figured that could be shooter error and no big deal, but then out past 400 I would notice inconsistent fliers from out of no where and the rifle would start grouping "up there" and then suddenly go back to where it started ........I kept having to chase my zero one click hear or there (mostly elevation) and then chase it back. After all sorts of cleaning rueteen modifications and a little load tampering.....I moved the big scope to the wsm and it worked great. Put the ten power back on and she went right back to driving tacks. But after being spoiled I could not live with that arrangement. When reinstalling the beast I marked it with a pencil line and did some shooting and she drove tacks for a while, then after a couple sessions she started doing it again I thought maybe it had slid "maybe" then I scratched a small cross behind the rear ring right on the edge of the joint where the rings meet and it started to show slight movement and just to bust you noggin=slight movement back. after this I tried all sorts of stuff to make them work... powdered resin, locktight on the inserts, new screws oiled, new screws locked, new inserts....... Waiste of time and ammo....your situation sounds mechanical.....that's a very likely canadate.....I love the rings and the ability to add moa with offset inserts but you could not pay me to try them again on a big rifle. We use them on our 7mm with no problem at all and I figure that is a good place for them. By the way, since I went overkill on my mounts I have not had any trouble or even a doubt since. She will hold 1.25"@400 or 4"@900 any day, weather permitting.
