I have a Lancaster SLE, circa 1920, that was jug choked somewhere along the line. Bore diameters are in the 732-733 range, so it has not been honed very much. Minimum BWT in the neighborhood of the "jugs" is still mid-20's. That far down the tubes, pressure isn't really an issue any more. However, I agree that if barrel walls are already thin and jug choking would take them below .020, then the risk from denting might well become a more serious issue.