Re: Free Float Barrel Clearance
I have 2" wide electrical tape.
I apply five layers (nominally a total of .025") to the underside of the barrel and then apply release agent over that. The barrel is now properly set up to use as a bedding mold/mandrel for the barrel channel.
Making certain there is significant clearance between the hogged out barrel channel and the barrel with the stock bedded and tightened, apply bedding compound to the channel, then tighten the barrelled action into the stock, allowing any excess compound to escape around the barrel. Squeegee the excess off and allow the compound to cure.
When it's cured, pop out the barrel, remove the tape, and a consistent .025" gap should now exist that conforms perfectly to the barrel contour.
Gaps that are too big can allow foreign matter to become trapped under the barrel, where it's hidden but still capable of providing solid contact. Periodically sweep the gap to ensure there's nothing lurking down in that gap.
Greg