pillar bedding 7mm action into boyds varmint thumbhole

I am ready to bed my action and just had a few more detail questions. First, I plan on bedding the action and pillars together. Will using the action screws bind the action in anyway during the process? My tang is free floating and I will tape the barrel in front of the nut. The in letting inside the stock was good for the mag so I measured my pillars off of that and removed wood for the bedding verses raising the action. I have used 3/8'' lamp rod for the pillar material. How much should I over drill for them 1/16, 1/8? The in let for the trigger guard is just about 9/16'' wide guess I'm worried about nicking the edge with my bit.