I must admit that in the numerous times I've cleaned the barrels on my doubles, I've not paid a lot of attention to that dark ring about three inches in from the breech. Inspecting the new set of barrels from France, I used the summer sunlight to shed light on and in the tubes. That dark ring was so pronounced it looked like a shoulder instead of a slope.
A soft wooden dowel confirmed that it was indeed a slope, the half-inch or so of unpolished forcing cone.
So that got me thinking (usually bodes ill): If one uses a proper length shell that does not open into the forcing cone, and said shell's shot cup does not encase the full load, wouldn't there be the potential of some serious barrel scrub? So why wouldn't one polish the forcing cones? Just for grins, I looked at the second set of barrels for the Arrieta, made fifty years later than the Manufrance, and it had the same appearance. I cannot thus conclude that all doubles have unpolished forcing cones, but I can infer that it was/is a common practice.
Mike
