I believe that some barrels on high end Brit ("Best") guns are polished to a high degree and then burnished to close up the pores in the steel before bluing. This accounts,I think, for the high gloss barrel finishes.
Chukarman;
Interesting thought on burnishing. Likely very difficult to burnish long tubes, however I do not know what I do not know. Have you encountered any evidence to suggest burnishing?
Along the lines of the comments of this post, I would like to add to the thoughts of this discussion the following: (1) Desmond Mills, the ex-Purdey English gunsmith and co-author of "Amateur Gunsmith" has a "one liner" in his book that shotgun barrels should be polished to the point of appearing as if they are chrome plated. (2) In Donald Dallas book of the history of David McKay Brown, gun & riflemakers of Scotland, David says that in his shop after a set of barrels are blacked, they are then covered with soot via a gunmakers smoking pot and that the soot is used as an polishing abrasive to hand polish the barrels to the desired luster.
I have not seen one of McKay Brown's double guns or doubles rifles in person, but viewing photos of them in Dallas' book they do not appear to be of the gloss/luster that one sees of new Purdey or Holland guns. Brown's guns and rifles are blacked in-house at his shop.
A thought that I have about the blacking of barrels that have been highly polished as described by Desmond Mills is the carding away of the rust after each boiling cycle of the blacking process. Some and maybe many American barrel blackers use the Grobet (a tool maker to the jewelers) very fine wire 6 inch diameter jewelers wire wheel to card away the rust. It occurs to me that this revolving wire wheel,even at low RPM, could produce unintended results of dulling much of the finely polish barrel, and that maybe 0000 to 000000 steel wool should be used to card away the rust.
Secondly, Angier states in his 1936 book that weaker (less aggresive) browning/blacking solutions produce finer grain and glossier finish than do stronger solutions. A couple of years back I polished away the surface of a recently blacked barrel, just enough polishing away to where the barrel surface could be examined under my engraving microscope. This barrel had been final polished with 1000 grit prior to blacking. Upon examination under the microscope the surface looked like surface of the moon--just a mass of pits. Thinking about this pitted surface afterwards, it occurred to me that not only weaker blacking solutions, but also shorter rusting periods could produce less deep pits during the barrel rusting. (noting that the deeper the surface pits the less light is reflected back thereby making the surface seem duller). Angier seems to suggest that with very high humidity, say 80-90%, very very short rusting cycles can be used maybe 1 hour to 1.5 hours. Under this same thought process it seems likely that once a certain number of rusting and boiling cycles have accomplished that further rusting and boiling cycles will produce no better results and maybe even produce negative results as to appearance of the final finish.
Lastly, the late English gunsmith, Jack Rowe thought that Willi Barthold, the German master gunsmith and German professor of gunsmithing, was the greatest gunsmith who had lived in the last 100 years. Barthold's German language gunsmithing textbook:
"JAGDWAFFENKUNDE" (1969 VEB VERLAG TECHNIK, BERLIN) was recommended to me by Jack (which I bought). Jack said that when he emigrated to America that he could not find anyone in the USA who could produce barrel blacking to the standard that Jack was desired and received from the barrel blackers in England. Jack further said that he contacted a gunsmith that he knew in California (formerly UK gunsmith) and gave that gunsmith Willi Barthold's barrel blacking formula (from the textbook) and that with some minor adjustment the California gunsmith blacked barrels to the standard that Jack required. Willi Barthold's blacking formula turns out to be the same formula that Angier lists as Swiss Black at the top of page 88 (C. 17) of his book. The formula contains only Copper Sulphate, Ferrous Sulphate, Ferric Chloride, distilled water and Alcohol. During several conversations that Jack and I had about gunmaking, he stated his belief that barrel blacking solutions that contained nitric acid could not produce gloss finish barrels. I do not know if this is correct as I had not tried to see if that was the case.
