Rudybollo,
I agree that .040" is too much, but You won't know unless you try it. If the cases hold together, don't size them back to 28 ga., that would be sure to split them. If you try it, wrap a thin strip of tape or file label around the case, ahead of the rim, to center the case in the chamber( so the whole .040" isn't on one side, tape can be removed after first firing). It looks more and more like you will have to buy a lathe and learn to use it.
Mike