I may pick up an ol' crotch English hammer gun of 12 gauge with "dark and pitted" damascus barrels. Shows overall long and hard use for a circa 1900 gun. I would like to do a mechanical restoration of the barrels and perhaps reduce to a "backbored and opened" 16 gauge. That would be a worst case circumstance if barrels clean up thin and weak. Thus the original barrel would be a carrier for the sleeve which might be a 16 ga. The chambers, expected to be bad, would also be sleeved to the proper gauge. Barrels are 30". Chambers are likely 2.5". The object is to fire a 2.5" 12 or 16.
Let's assume we trim the bore true and determine diameter. This can be done via solvent application, hand brushing followed by some light emery work, and more washing with penetrants. This should have loosened globners of oxidation without tearing them out by the roots and thus making deeper pits.
My inclination is to go down the bore with a slotted dowel fitted with a steel rule strip of whatever thickness but with a taper on the leading edge. This would provide a fairly straight edge which should scrape the bore reasonably true of embedded oxidation. A technique similar to this with a tapered dowl is/was used to make bagpipe chanters and oboes. With the bore cleaned out it could be progressively honed clean.
Now: What sort of sleeving material can be used? I have shotgun barrel blanks made from chrome moly tubing. Should we take a proper grade of similar material, cut to length and grind the interior or exterior as required, and then slide this in? What is a preferred fastening method which would not promote corrosion of the imperfect damascus mating bore surface? In that regard it might even be practical to use Brownell's Oxy hand applied "blue" as it seems to be a chemical neutralizer that dissolves rust. The other consideration is the insertion of the sleeve and what the tolerances and techniques are for that operation.
Had a damascus 10 gauge "chamber" sleeved to 12 by Briley here in houston. Jess has been sleeving shotguns since the early seventies. Made a good big company from taking care of skeet shooters and the like. A point to remember is that sleeving will not much improve the strength of damascus unless of course you go down several gauges, so the sleeve has some real strength. It is not safe to shoot even low velocity smokeless loads in them. Black powder for me, thanks [img]smile.gif[/img]
You might consider electrolytic restoration of the barrels before just mechanically removing the rust and corrosion.
Even after that, I would sleeve with barrels that would carry the whole load themselves rather than relying on the original barrel for anything other than cosmetics. But gun weight will go up and swing will be quite different.
John...used to shoot some one oz. loads of ( i think it was) sporting rifle 7625 powder in a greener hammer damascus trap gun .....max psi was at black powder levels ,but the curve was different...won a few matches cause everone nearby was trepidatious abt running fer cover....wud not have done this w/ a hardware store belgian import ( "Barker" bros was one i remember),but the old greener had remarkably smooth/clean bores...reckon it helps when u have a servant to clean em
I find topics on the old doubles very intriguing; unfortunately I am not qualified to comment intelligently on matters as serious as the one you propose to undertake.
About the only appropriate advise I can offer is: any error must be on the side of caution! You are talking about life and limb.
Would you consider consulting with Briley about 20 guage tubes? Their advise would be among very few that I would not hesitate to consider.
There are some people who are shooting the old damascus guns but I doubt they are in the condition that you are describing. Some damascus guns have reportedly been reproofed for smokeless but I suspect they were very good specimens.
I am skipping that particular gun and instead got something missing some parts but in allegedly better bore condition - if fact the whole gun was better. Basically a circa 1900 or so needing some small parts which can be turned or hand formed from stock. I'll see when it comes. My issue is now to do research on this nice Belgian common grade gun or at least determine from construction what quality level it represents.
This is a back action item with rather nice flamboyant hammers. An estate item which due to missing parts was apparently unused for a long time which is why it is described as being fairly tight. Time will tell.