Just to clarify something here with respect to A H Fox guns. Many
original Foxes have tubes that
do not touch at the muzzle - hence "tubes touching" is not a definitive test of original barrel length for Foxes, either Philly or Utica made. That may be valid for some makers but please let's not perpetuate that notion for Fox.
Regarding the Sterlingworth cited here - from the postings it would seem the barrels have been cut from 30-inches. Fox barrels could run up to 3/16" or so short - but I've never seen anything like 7/16" overlength on a Sterly. That would rule out longish 28-inch barrels on this gun, at least in my mind. Fox "full choke" for regular 12-gauge guns (not Super-Fox) will average ~40 thou constriction, plus/minus a few thou. Andy, you may want to check the calibration on your bore mike. 41 thou constriction with cut barrels isn't what I would expect with Fox tapered choke(s).