Having recently had my Nikon 10.5mm shaved I'm experimenting with using it with my D800 on the R1. At 0 degrees a dark patch is noticeable at the zenith so I prefer to use +5 degrees instead. I have found it works just fine at the recommended 1.1 setting, however it doesn't seem to lock off as securely as it does at 0 degrees and +7.5 degrees.

Would I be right in thinking the screw only tightens it against the stop between the two holes so that if any force is applied it will slip off? Or am I doing something wrong?