A member here, and SE AZ winter visitor, very kindly made me a gauge. I am NOT mechanically inclined but Gloria a Dios the dang thing is easy to use, and works!!
With the .038 curved strip to zero the micrometer
Top to bottom:
Upper arm with brass stop
Micrometer leg under spring pressure
Lower arm with screw to tighten a brass shim (inside the arm) to hold the micrometer in place
24" plastic tool box with 2 bungie cords holding the barrel. It was quite steady with the usual gun cleaning stuff inside, and the cords allowed the barrel to be rotated and ends swapped
Muzzle extending well past the box, with 20" of yardstick
Measuring the wall thickness per the Hosford YouTube
http://www.youtube.com/watch?v=1jQZn4kohH4 
I started with Fox barrels that Briley honed from .724 to .727, or .0015 from the barrel wall, completely removing what I had thought were fairly deep pits.
Measurements were very consistent right/left and the length of the bore:
Just past the forcing cone which I had Briley lengthen - .110
9" from the breech - .045 then to .034 the remainder of the bore until the start of the choke constriction.
I'm very pleased with the gauge, and owe my friend a nice meal and drinks in Sonoita next winter!!
