Nice preservation effort there, Mr Waterman.
Consider this approach: fellow name of Paco Kelly makes an "Accusizer". It's a swedging/swageing device that allows the user to bump up the rimfire bullets to a uniform diameter. As well, he has assorted nose punches with which to reform the bullet, while it's being swedged. The old Hanned Line was similar, but not exactly the same, so far as I know.
I've read several first-hand reports noting increases in accuracy, even with bulk-box .22 long rifles. For a review of the original product, subsequent improved products, and a new flat-point shearing tool GOTO Gunblast.com and use the search engine. Also, Rem40X may have some additional info on the inventor and his product.
Paco Kelly, as many of you may be aware, has some few articles on shootin' subjects, and available thru the Frontier Sixshooter or Leverguns.com forums.
At any rate, it's possible that you could get Paco to make one of his swedgers in a size that would fully use your remaining rifling. Another thot, tho it is a bit of risk, is to consider fire-polishing of the bore with extremely fine rouge.
I have used fire polishing on a good many military Enfields, starting - in some cases - with some pretty rough grit. Of course, THAT is some quite robust rifling compared to your case. FYI, generally, one can occasionally go from a dark and nearly non-existent bore, to one that exhibits the remaining tips of the pitting and corrosion only with a Hawkeye bore scope.
I venture this only as information for those Brothers in Rust, who perform resurrectionist feats upon the nearly deceased barrels, which merit return to operating condition. It's a tedious process, and while it has been safe for me, I can't warrant pressures, results,and Ye Auld Etc.
BTW, made it to Tulsa this past weekend, and i will never again believe that colts and winchesters are rare -- because THOSE guys own most of them already. The rest are prolly in Vegas and auction houses. Did see a fair amount of nice SxS's and their vendors, tho.
