The factory pillars are not contoured to match the curve of the action. They are made flat for a reason. Pillars are not designed or intended to "support" the action in he stock. They are there for one reason and one reason only, that is, to prevent the action screws from compressing the stock material when torqued. If you try to contour the pillars to match the curve of the action it will likely not be a perfect match and the pillars will end up pushing the action one way to the left or right. Not good. They should be cut flat on top so that they only touch the bottom most under-side of the action.

If you want the action "supported" somehow, then you should bed the action to the stock with a full bedding of some kind of epoxy. When you do this, the bedding material can be poured deep enough to allow it to flow a bit around the tops of the pillars so there is full contact (perfectly matched to contour of the action) with the action as opposed to what you've already observed.

If you bed the action properly, you will notice the action screws turn freely then suddenly STOP when tight. If there is a gradal tightening of he screws then you should re-do it b/c that is indicative of some sort of binding or uneven pressure being applied to the action, which is exactly what you are trying to eliminate.