I've done what 'thejanitor' said, set screw and O-ring. So far it's worked good. Played with the depth of the set screw a little... in all the way, then back off a little at a time until it seems right, then locktight in.
Some folks use a torque screwdriver instead, but that seemed to complicated, and another tool to 'forget' when I'm going shooting.
Hardware store O-rings... 3/8" I think, is what I got.
Be Well...