Not a good concept.
It is best to have a free floating barrel.
Dont mince your words now GQ....just say it as it is

LOL.
Just to clear things up it is my belief (and experience from a badly fitted stock on my Tikka .243) that-
It is only 'best' to have a free floating barrel when having a fixed barrel will cause a problem where it is likley that barrel heating/ and or enviromental changes can cause the barrel or forend to expand/ retract/ create unwanted contact against each other that results in an unwanted POI shift.
This is of course possible on an airgun with a wooden/ laminate/ even composit stock, but not on an Impact.
The one place where you may potentially see materials contracting against each other on the Impact is inside the barrel/ shroud (note- my crazy, off the wall, revolutionary, brand new invention- that I shall call 'a barrel band'

has an intergrated 28mm oring for the barrel support allowing for expansion)
As Heavy has pointed out, FX have already put different materials/ alloys together and then put them under tension no less... which should possibly be of greater concern.....
As pointed out by Mercado, in reality, for 99% of shooters a free floating barrel on an airgun doesnt make it more accurate.
GQ- I generally only hunt, so for me a vunerable free floating barrel has disadvantages compared to a correctly supported barrel
