I am presently running the .308 version of that mount on a bolt gun. Although not observed in this configuration, I did encounter a similar issue when I first mounted the glass using the original, two piece split rings. In my case, the Nikon rings were designed for a Picatinny rail while the rifle used a Weaver pattern. Despite the fact that it was secure enough to withstand recoil without movement, one of the mounts was not properly seating - thus deviating from the bore axis. Once I figured that out, it required only a few short minutes with a Dremel to resolve.