Glass bedding is usually really bedding the action in a polyester resin to help achieve perfect contact. I.E. no movement of the action if the action screws are loosened or tightened. Most simply bed the front action screw the recoil lug and a few inches of the swelled area or the barrel just in front of the front ring, called the barrel re-enforce. Free floating the barrel eliminates contact of the barrel and the channel in which it lies. The main reason is that wood absorbs water and swells. As it does it is usually not even so the pressure the stock would exert on the barrel would be variable and will cause the rifles zero to wonder. If the barrel is totally bedded and the resin controls the movement of the wood the contact CAN provide a deadening effect.. Remington installs a pad in the barrel channel of their rifles to push up on the barrel helping to control vibration which does help accuracy, they relie on their urethane finish to keep moisture transpiration down. Their rifles are known to be unusually accurate. The current trend is to float the barrel, after the action is securely bedded to keep the zero as stable as possible. this is a very debated topic and there are many opinions. Pillar bedding is installing an immovable material (aluminum, steel, or even bedding material) in the stock between the action and the bottom metal where the action screws pierce the stock. This is glass bedding with a spacer included and was really kind of developed to keep good bedding from changing as the wood between the metal components of the action from compressing over time. There are several threads in the gunsmithing threads that might provide some guidance, especially should you wish to try it yourself..
