I took the new 700 7mmRUM to the range for the first time yesterday. It already had a one piece Leupold style bases on it so I bought some matchings rings for it. I centered the scope for windage (it came off another rifle) then used the rear base to adjust windage during the bore sitting. After about 10 rounds I am still at the same point on impact...so I move the scope again! I have the gun on a bipod and sand bagged well...set the scope back on bull and move the cross hairs to the bullet hole. It would be about half way to where I wanted it on the next shot and back to the original spot after another shot!!! Somewhere around the 15th to 18th shot I run out of scope adjustment! Thats when I noticed the rear ring was not longer centered on the rear of the mount. I forgot my screw driver and bent a penny trying to get the windage screws loose. I tend to overtighten...any way I recenter the mount and my windage is WAY off...recenter the scope and start over. It stayed this time, but I am very worried about the mount doing that again. I don't normally buy this kind of mount...does this happen often? BTW-it shot less than 3/4" groups after that with Remington factory ammo. OMT-Limbsaver recoil pad was money well spent too!