I wonder if the acid wash/treatment of the relatively rough tubes was to remove forge scale. It may have been a way for the smith to quickly scan for defects. Forge scale can also be pretty tough and the various rough machiners may have preferred that it was removed first. I wonder what acid treating would do just before shipping, I don't know, maybe it was better around an ocean environment, but?
I would guess that a basic pattern might, or might not, be seen, but to be discriminating about it, I'd think tubes would have to be brought to a relatively high surface finish, before etching, to see the pattern. Truly special order tube sets, or standard pattern extra fine sets, would probably have to be kept paired from the original forging shop, through the whole process.
I wouldn't think much resources could be spent digging through stacked rough barrels. There may have been confidence in how a barrel would finish if it came out of a specified order, but, luck aside, truly mirrored matching and other intentional patterns probably required a price premium. In most cases, particularly in production, it seems like the barrel tubes were nothing more than a component.
