Some above have intimated this, but let's be very clear. You can glass bed an action and still allow the barrel to float. Glass bedding the action involves the tang area and the area behind the recoil lug. I also bed the barrel about 2-3 inches ahead of the recoil lug and let the rest of the barrel float. Sometimes I install a metal pillar in the front action screw hole, and sometimes one in the front and one in the rear action screw. Some folks also bed the sides of the action.. I do not.
Ballisticians tell us that a rifle barrel vibrates in a certain pattern when a shot is fired. Harmonic vibrations? If the vibrations are uniform from shot to shot then we will have good accuracy. My take on this is that a fully bedded barrel, action to end of foreend, with a snug fit, may help to promote uniform vibrations, and the bedder may see an improvement over the unbedded barrel.
However, if there is interior strain in the metal of the barrel, then barrel heating will cause uneven expansion and pressure points will develop in the closely fitting barrel channel. Accuracy will suffer, and it can be serious as you will know if you have ever had a rifle that developed uneven contact, side to side, at the end of the foreend. I think the floated barrel generally works because this situation is avoided.
The new generation of economy rifles, of which the Remington 783 is about the latest, have plastic stocks and some kind of solid bedding, either with pillars or metal inserts, and free floating barrels. Reports in the shooting press promise very fine accuracy. I love wood and I love vintage rifles and cartridges. And I love to do bedding and other accuracy tweaking, so I stick to that. But I am curious. Do these new plain rifles really perform? Anybody have any experience to report with them?