DPL,
Cheers for that. I am glad that, subject to your mentioned provisos, the bead blasting is generally ok as I think there is not much alternative with the majority of the scopes that have been to India. I don't know if there is an explanation for this but the pitting always seems to be deepest where the tube is thinnest (ie the ocular end).......!! Maybe this is because scopes were left for years in humid conditions with the lens caps left on....??? Here, if it is bad, I would agree that replacement of that part of the tube with a donor part from a No42 or 53 is a good idea. I think you know that my late machinist salvaged a few scopes for me by this method, some years ago. He silver-soldered them for me though, rather than threading & soft soldering. It seemed to work.
ATVB