over on 6mmbr under technical articals Richard Franklin offers a dvd on stress free pillar bedding with devcon 10110, also he uses leftover pieces from barrels to make pillars. The v-blocks only make a very small contact area with the action, however if you bed the action that has a v-block you will get more contact area and less chances of slippage under recoil.
at least that's how it was explained to me.
if you do have a v-block stock, make small dimples in the aluminum with a drill bit that doesn't actually make contact with the action and rough up the area for bedding material to adhere to, but make sure you do not rough up or dimple the part that actually makes contact with the action.