From the single rifle I tried this on, twice.
Original barrel: Sporterweight douglas premium, 24"
Bedded the action/free floated the barrel: It shot well about 3/4MOA @ 100.
Bedded the barrel all the way to the end: Again it shot about 3/4 MOA but shot it at a lower velocity.
Free floated the last half of the barrel: Again it shot avout 3/4 MOA but at a higher velocity.
Did the same thing when I had it rebarreled w/a 27" Lilja #4 contour.
Got the same exact results except group size is .3 or .4 MOA range.
Stayed with the first half of the barrel channel bedded.
Mauser 98 Action - 270 Win.
Conclusion: Messing with bedding of any part of the barrel is pretty much a waste of time except its fun to play with once just to see.