I think the reason so many builders are so concerned about full length octagon inletting of barrels relates to the fact that when a barrel is inlet on a duplicator, as in all the kits, it's as easy to get an octagon as anything else. So the thought immediately sets in the brain that the channel has to be octagon the whole length. Also very, very few beginning builders have had the opportunity to see the stock of a pre 1820 rifle without the barrel in it. The barrels aren't floating in the type of inletting we've been talking about. They bear completely on the side flats and hit almost the whole length on the corners of the bottom flats. The forestocks are, for all intents and purposes, just as tightly held to the barrel as in a full length octagon inlet. It should make no difference whatsoever in shooting unless one has a tight spot on a full length octagon inlet that binds the barrel.
Tom