What is the proper way to bed a rifle into a stock that has pre installed pillars? Do you just set the action in the bedding, and let it settle, or do you torque the action screws down, so they have metal to metal contact with the pillars?

I snug the action screws, but there's no need to torque them down, or for the action to contact the pillars.

First thing I do is run a drill bit in the pillars. Makes it easier after bedding to clean out the excess bedding from the insides.

Wrap the screws with tape to center the screws in the pillars.

I tighten them just enough to barely make contact.

+1 Yup

What would be wrong with using headless screws, screwed into the action, to keep everything aligned, and allowing everything to settle into the bedding on its own? Wouldn't that guarantee that the bedding job would be 100% stress free?

Also when you say you run a drill bit through the pillars, are you removing any material, or you just making sure they are clean?

You need something more than gravity involved in getting the action to "settle". The bedding I use is thick and if I relied purely on gravity, it would begin to cure faster than that action would settle.

I draw the screws up snug but not tight (and especially not farmer tight) and allow everything to begin curing for a couple hours, then I use masking or electrical tape to keep everything in place and back the screws out.

Works for me...as for the drill bit, not really sure what they're talking about.

When it's all said and done and the action is popped out, I do run a bit through the screw holes to get rid of any compound that seeped, squished or otherwise ended up in there.

I'm not a pro at this, but like I said, it's worked will for me each time.

Good luck,
Rob

I'd test the pillars first to verify that they are installed properly and not stressing the action first. Then snug up the screws tight, back them off and wrap surgical tubing around the action/stock to hold everything in place while the epoxy cures.

They seem to be installed properly. It is a custom ordered McMillian, so I would tend to trust their install.

Prop everything up, sit the barreled action in the stock (using headless screws if you want), and maybe sit a small sand bag on top if things won't stay in place. Typically only an issue with long barrels that might not balance well. NEVER tighten down the screws. That undoes everything one is trying to accomplish.

I'd skim bed w/ bedding screws, or stock maker screws in a pinch, and surgical tubing.

If being anal, McMillan published a paper on the subject reference crush strength of their bedding vs machined pillars. Other than having a lightweight bench rest construction in the action area, normal construction cannot be crushed by torquing action screws. They found pillars add no strength over standard fill and epoxy bedding, but they continued to offer machined pillars for the sake of technique and demand.

It is impossible to machine pillars to perfectly match the mating surface of the action and bottom metal, so a skim bedding w/ bedding epoxy would serve that purpose, while maintaining crush strength once cured. Some use the technique of relieving the pillars to ensure a place for the epoxy to fill and cure to a stress free mating surface.

If a ligtweight bench rest construction where pillars are critical to provide enough strength to resist crushing. As above, using epoxy to ensure a perfect mating surface, vs bare machined pillars, would aid toward having a stress free fit, and would not negate the crush strength of the pillars when torqued.

Not sure what they use now, but McMillan was using Marine TeX Epoxy Grey for all the above. Good stuff, especially if hard used and/or high recoil.