Has anyone tried the Grayboe stocks yet? They are spin off
from McMillian.

I have used one of the A5 clones. I believe that they all come painted with a pad and studs installed along with pillars. The paint, pad, etc. looked fine.

Though they are designed as a "drop in", I had to open up the barrel channel on mine to accommodate a bull contour. Because they are solid fiberglass, I didn't have to worry about breaking through to the "fill".

My only complaint is that the ID of the pillars is fairly generous-- this is great for a drop-in but I would like to be able to control those dimensions by reaming the ID to size after the bedding process.

I would not hesitate to use another one so long as I wasn't overly concerned about weight.

Why would you consider reaming a pillar screw hole to size?

The way I was taught bedding was to start with pillars that have an ID of .250" so that there's minimal play, bed the rifle, then ream the pillars so that the guard screws don't impact the inside of the pillars during recoil.