Have done several Ruger actions, you need enough of a hole for the bedding compound to have some bite on the pillar. You want a mechanical lock taking place. If the pillars you have are smooth, I would have someone turn 3 grooves in the outer surface to create this mechanical lock.
I have always made my holes for the pillars 9/16". You can buy the correct counterbore drill bit through Brownells, if you wish.
I have always found it best to pillar bed first, then bed the action, recoil lug and barrel as a second step and the tang last on Rugers. I do not bed the centre of the action around the mag well, I use this as the area that supports the rest of the action while removing material for the bedding compound. Other people may do it differently, but this always works for me. I have also done the pillars and recoil lug in one step, then the barrel and then the tang, but the results weren't as neat and compound found it's way into the mag well. I find bedding the knox form for 2" gives the best results with the rest of the barrel free floated.
Hope this helps.
Cheers.
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