Question for Dawson rail users

I sent my frame out to Dawson a few months ago and had them add their rail to my gun I'm having a couple issues with it though.

Issue #1: The fit- I added the adapter to a X200 I had lying around. I don't know if it is just mine or if this is a common problem, but when I adjust the set screw in the front if it is tight enough to make it so that the light doesn't rattle then I cannot remove it. The light rattles both forward/back and side to side if the screw is not tightened. Also, the screw loosens after shooting 75 rounds or so. Any fixes or thoughts on this?

Issue #2: Uncomfortable on support hand - I use a standard thumbs forward grip. When the gun recoils the top of the Dawson adapter on the light smacks my support thumb. Is this normal? How do you grip your guns?