I would agree with surpmil, although I feel it is worthwhile, where pitting is not too deep, to strike it out with slow diligent work with a Swissicon file, then progressively finer grades of abrasive paper. If pitting is not too deep it can be completely lost, & even if deeper can be greatly mitigated. If the scope is to be completely refinished I cannot see any harm in doing this, & it will permit of an original style rust-blued finish. Welding is an alternative & is fine with suncorite or other painted finishes, but tends to show as variably shaded areas with blueing. Great care has to be taken to rock the file during the striking up process or you will end up with horrendous flats on the scope body, but this is avoidable with care. It is also very time consuming & tedious - I have spent many hours just working on a single scope tube, but the results were worth it in the end. It is sometimes possible to hold a scope tube in a steady on a lathe & spin it, but this is something to be avoided where you wish to preserve original engraving (of course if you can get engraving gone over in the original font that is even better).

ATB