I would plug the hole, if it was mine. Is it needed? Probably not, but, for me, the plug would stop any gas from escaping under the rail.
Lol, see my post above yours.Pick up a short allen head set screw.
I've never done this, but, I'm wondering if Flitz Polish or similar, applied in strategic places, and cycled many times would smooth out the action any.
Everyone is looking for the finished grip.
How does it look outside in natural light?