This is what I figured. The lack of standardization is amazing, all these small workshops working by natural light and oil lamps filing, hammering and twisting away to produce what are essentially one-offs that are hand-made to fit a specific action. No wonder they serial numbered them. I wonder if you found a barrel set that had the same initials stamped in them would they be roughly to the same spec. My Osborne has WR stamped on the underside. I will update how close (or far) the barrel set us from fitting once they arrive. Either way it's good to have a barrel set to practice working on without fear of rendering an entire gun scrap.
