It was. I have them .30-06, .308, and .222. The case was driven into the neck sizer, same as a basic Lee loader, but you then ran a captive reamer in that thinned the case walls about 0.001" to achieve uniformity, doing it from the inside as opposed to the outside neck turning done today. The primer was seated with a separate hand tool, rather than hammered in, as with a standard Lee loader, and the bullet seating ram had the micrometer adjustment on it with graduations, rather than the nut on the current generation of Lee Loader.
This tool was made by Lee Manufacturing. When Lee got out of that business (I think to escape co-owners) he started the current Lee Precision company. But that Zero Error design never made it into the new company's product catalog, so used ones are all you see today.
