Thanks Marrakai,

being a scientist I know that it takes much more than what I suggested to find an empirical solution to DR regulation. I'm inclined to think, as I think You're too, that there really is no other method than to shoot & re-solder for a true regulating of a double.

I've loaned my Ellis Brown to one gunsmith friend of mine, so I can't refer to to it right now, and I can't recall the essence of Brown's rule-of-thumb. A quick peek on Gray's 'Hammerless DR', however, is enough to convince everyone about the necessity of the trial & error method in final adjustments.

My idea is just to find some support for the FIRST setting of barrels under construction in home shop, so that the margin of error would be as small as possible for the real final regulation at the range.

You're right that I didn't really think about the curvature between the throat and muzzle in each barrel but, on the other hand, I do not buy that "last inch" statement of yours as such. Although I reckon it to be more of a figure of speech.

My copy of Wright's "Shootin' UK DR" is away with Brown's book, and can't refer that either. But if I recall it correctly, Wright mentions something about the last 4-5 inches of the muzzle in soldering-resoldering, but as I said, I'm not sure. Does any of you have the Wright at hand?

Regards,
Saku