Just staggered in. Yeah definitely worth running the wire wheel over them first, except keep it way from the cutting edge and gimlet of course. The citric acid works best if the waters boiling to start. For long things like these I use a bit of tubing corked at one end but they are so wide you are looking at drain piping or doing them sideways on in a bit of guttering. Or scrape a small trench and peg a rubble sack or something like mini lined pond. I once tried to use a 2 litre pop bottle, the boiling water made it contract around the piece I'd forced into the cap end and once it was pickled I had to cut the damn thing off. Interesting and all alarming to watch at the time as as it shrank boiling water spewed out of th top...
After a couple of hours they will have pickled as much as they are going to. They should be shiny bright on being pulled out of the liquid but will , if they behave like some I've done, turn black/brown very quickly as the cleaned surface seem to be incredibly prone to rusting. In theory I've read you could leave it as a finish but it sticks in my craw so I give mine a light run over with the wire brush which seems to remove this super easily corroded layer of molecules.
Some I've seen are painted down to all most were the helix starts, some have been all blackened chemically and som bright metal from new. It's what ever floats your boat the helix is usually polished
Best thing to do now is try it on some scrap wood as I've got to this stage and the thing, under the rust, has been as sharp as when the last user prepared it for the next job and put it away.
If its not sharp then it's pretty much what you said you'd do, a bit of filing. Would those small stones I sent be of a size to put a final edge on?.
Since they are all two foot long I'd guess they were for ship building, for the big copper bolts and treenails. Even a small ship would need surprisingly long holes in it! The 40s are quite haphazardly stamped on so probably applied at a yard where they would be a set owned by the firm rather than a workers personal property. They belong to a age when you'd have your name stamped on your own stuff. I keep threatening to have a stamp made up for mine but am too cheap!
Very good point about keeping the cutting end wider than the rest of the helix. I don't touch them if the working ends more rusted than the rest as that will be eaten away by the citric acid and you'd have to grind the rest down.
ATB
Tom